"目录一、在 Web 项目中启动 Spring 容器 1.1、使用监听器启动 Spring 容器 1.2、使用 Servlet 方式启动 Spring 容器二、获取 ApplicationContext 实例 2.1、使用工具类 WebApplicationContextUtils 获得 Spri ...."

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Spring学习总结（五）——Spring整合MyBatis（Maven+MySQL）二

一、在 Web 项目中启动 Spring 容器

二、获取 ApplicationContext 实例

接着上一篇博客《Spring 整合 MyBatis（Maven+MySQL）一》继续。

Spring 的开放性和扩张性在 J2EE 应用领域得到了充分的证明，与其他优秀框架无缝的集成是 Spring 最为强大的功能。Spring 类似电脑的主板，可以将许多部件集成在一起协调工作。

一、在 Web 项目中启动 Spring 容器

在 Web 项目中当 Web 容器启动时我们要同时启动 Spring 容器，有三种办法，第一种使用监听器启动，第二使用 Servlet 启动，第三使用 MVC 框架的扩展点启动，这里主要选择第一种，因为监听器的启动时机早于 Servlet。强烈建议使用办法一。

1.1、使用监听器启动 Spring 容器

我们需要使用到 Spring 定义好的一个监听器：org.springframework.web.context.ContextLoaderListener，该监听器在包 Spring-web.x.x.x.jar 下，修改 pom.xml 文件，添加依赖：

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-web</artifactId>
            <version>${spring.version}</version>
        </dependency>

修改 web.xml 文件，新增监听器声明，代码如下：

    <listener>
        <description>Spring 容器启动监听器</description>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>

当监听器在启动 Spring 容器时会自动查找 Web-INF/lib 目录下名为 applicationContext.xml 配置文件，当然也可以设置参数指定配置文件的具体位置，特别是有多个配置文件的情况，指定办法如下：

    <listener>
        <description>Spring 容器加载监听器</description>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath*:applicationContext.xml</param-value>
    </context-param>

如果有多个配置文件则可以通过逗号分开。怎么判断是否启动成功，则可以参考本文第二点，获得 ApplicationContext 实例，也可以查看 tomcat 启动时的信息，如果没有出现错误且能找到如下说明基本成功。

启动失败也有几种可能，如 applicationContext.xml 文件的路径错误；找不到类 ContextLoaderListener；如果提示找不到类，很可能是因为没有将 Maven 依赖的包发布出去，可以在项目属性中设置，如下所示：

1.2、使用 Servlet 方式启动 Spring 容器

方法与 1.1 基本相同，只是配置有小的区别，修改 web.xml 的具体内容如下：

<servlet>
    <servlet-name>context</servlet-name>
    <servlet-class>org.springframework.web.context.ContextLoaderServlet</servlet-class>
    <load-on-startup>1</load-on-startup>
</ servlet >
<context-param> 
    <param-name>contextConfigLocation</param-name>
       <!-- 多个配置文件之间以“，”隔开 -->
    <param-value>
           classpath:beans1.xml,classpath:beans2.xml...
     </param-value>
  </context-param>

需要注意的是两者都是继承类 ContextLoader，但从 Spring3.0 开始已经移除了 ContextLoaderServlet，用 ContextLoaderListener 的方式替代。第 3 种启动方式只有在特定的框架中才有效，所以不多用。

二、获取 ApplicationContext 实例

当 web 容器启动时 Spring 容器如果也成功启动了，则可以在整个 web 应用程序中获得 ApplicationContext 完成 IOC、AOP 及 Spring 的其它功能，获得 ApplicationContext 的常用方法有两种：

2.1、使用工具类 WebApplicationContextUtils 获得 Spring 容器

2.1.1、定义一个 Service 类，BookTypeService 代码如下：

package com.zhangguo.Spring61.service;
import java.util.List;
import javax.annotation.Resource;
import org.springframework.stereotype.Service;
import com.zhangguo.Spring61.entities.BookType;
import com.zhangguo.Spring61.mapping.BookTypeDAO;
/*


图书类型服务
*/
@Service
public class BookTypeService {
@Resource
BookTypeDAO bookTypeDAO;
public List<BookType> getAllBookTypes() {
System.err.println("一些被省去的业务");
return bookTypeDAO.getAllBookTypes();
}
}

@Service 表示 Spring 容器将自动管理 BookTypeService 实例，@Resource 表示自动装配，会自动从 Spring 容器中找到类型为 BookTypeDAO 的 Bean 完成 bookTypeDAO 字段的初始化。

2.1.2、定义一个 Servlet，BookTypeList Servlet 代码如下：

package com.zhangguo.Spring61.action;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.support.WebApplicationContextUtils;
import com.zhangguo.Spring61.service.BookTypeService;
@WebServlet("/BookTypeList.do")
public class BookTypeList extends HttpServlet {
private static final long serialVersionUID = 1L;
 BookTypeService bookTypeService;
 
@Override
</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span> init() <span style="color: rgba(0, 0, 255, 1)">throws</span><span style="color: rgba(0, 0, 0, 1)"> ServletException {
  </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)">在当前上下文中获得Spring容器</span>
  WebApplicationContext ctx=<span style="color: rgba(0, 0, 0, 1)">WebApplicationContextUtils.getWebApplicationContext(getServletContext());
  </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)">从容器中获得bean</span>
  bookTypeService=ctx.getBean(BookTypeService.<span style="color: rgba(0, 0, 255, 1)">class</span><span style="color: rgba(0, 0, 0, 1)">);
}

</span><span style="color: rgba(0, 0, 255, 1)">protected</span> <span style="color: rgba(0, 0, 255, 1)">void</span> doGet(HttpServletRequest request, HttpServletResponse response) <span style="color: rgba(0, 0, 255, 1)">throws</span><span style="color: rgba(0, 0, 0, 1)"> ServletException, IOException {
    PrintWriter writer</span>=<span style="color: rgba(0, 0, 0, 1)">response.getWriter();
    writer.print(bookTypeService.getAllBookTypes().size());
}

</span><span style="color: rgba(0, 0, 255, 1)">protected</span> <span style="color: rgba(0, 0, 255, 1)">void</span> doPost(HttpServletRequest request, HttpServletResponse response) <span style="color: rgba(0, 0, 255, 1)">throws</span><span style="color: rgba(0, 0, 0, 1)"> ServletException, IOException {
    doGet(request, response);
}

}

在 Servlet 中我们重写了父类的 init 方法，注意如果重写带参数的那个 init 方法 init(ServletConfig config)，则一定要记得调用父类的 init 方法完成参数的初始化，即不要删除 super.init(config)，如果不这样将获不到 servlet 下上文; 在 init 方法中我们通过 WebApplicationContextUtils 类获得得了 Spring 容器。

此时的 applicationContext.xml 文件如下：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"
    xmlns:aop="http://www.springframework.org/schema/aop" xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context-4.3.xsd
        http://www.springframework.org/schema/aop
        http://www.springframework.org/schema/aop/spring-aop-4.3.xsd">
<span style="color: rgba(0, 128, 0, 1)">&lt;!--</span><span style="color: rgba(0, 128, 0, 1)">属性占位文件引入，可以通过${属性名}获得属性文件中的内容 </span><span style="color: rgba(0, 128, 0, 1)">--&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">context:property-placeholder </span><span style="color: rgba(255, 0, 0, 1)">location</span><span style="color: rgba(0, 0, 255, 1)">="classpath:db.properties"</span> <span style="color: rgba(0, 0, 255, 1)">/&gt;</span>

<span style="color: rgba(0, 128, 0, 1)">&lt;!--</span><span style="color: rgba(0, 128, 0, 1)">定义一个jdbc数据源，创建一个驱动管理数据源的bean </span><span style="color: rgba(0, 128, 0, 1)">--&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">bean </span><span style="color: rgba(255, 0, 0, 1)">id</span><span style="color: rgba(0, 0, 255, 1)">="jdbcDataSource"</span><span style="color: rgba(255, 0, 0, 1)"> class</span><span style="color: rgba(0, 0, 255, 1)">="com.mchange.v2.c3p0.ComboPooledDataSource"</span><span style="color: rgba(255, 0, 0, 1)">
    destroy-method</span><span style="color: rgba(0, 0, 255, 1)">="close"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="driverClass"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="${jdbc.driver}"</span> <span style="color: rgba(0, 0, 255, 1)">/&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="jdbcUrl"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="${jdbc.url}"</span> <span style="color: rgba(0, 0, 255, 1)">/&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="user"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="${jdbc.uid}"</span> <span style="color: rgba(0, 0, 255, 1)">/&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="password"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="${jdbc.pwd}"</span> <span style="color: rgba(0, 0, 255, 1)">/&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="acquireIncrement"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="5"</span><span style="color: rgba(0, 0, 255, 1)">&gt;&lt;/</span><span style="color: rgba(128, 0, 0, 1)">property</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="initialPoolSize"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="10"</span><span style="color: rgba(0, 0, 255, 1)">&gt;&lt;/</span><span style="color: rgba(128, 0, 0, 1)">property</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="minPoolSize"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="5"</span><span style="color: rgba(0, 0, 255, 1)">&gt;&lt;/</span><span style="color: rgba(128, 0, 0, 1)">property</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="maxPoolSize"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="20"</span><span style="color: rgba(0, 0, 255, 1)">&gt;&lt;/</span><span style="color: rgba(128, 0, 0, 1)">property</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">bean</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>

<span style="color: rgba(0, 128, 0, 1)">&lt;!--</span><span style="color: rgba(0, 128, 0, 1)">定义一个jdbc数据源，创建一个驱动管理数据源的bean </span><span style="color: rgba(0, 128, 0, 1)">--&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">bean </span><span style="color: rgba(255, 0, 0, 1)">id</span><span style="color: rgba(0, 0, 255, 1)">="jdbcDataSourceBak"</span><span style="color: rgba(255, 0, 0, 1)">
    class</span><span style="color: rgba(0, 0, 255, 1)">="org.springframework.jdbc.datasource.DriverManagerDataSource"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="driverClassName"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="${jdbc.driver}"</span> <span style="color: rgba(0, 0, 255, 1)">/&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="url"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="${jdbc.url}"</span> <span style="color: rgba(0, 0, 255, 1)">/&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="username"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="${jdbc.uid}"</span> <span style="color: rgba(0, 0, 255, 1)">/&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="password"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="${jdbc.pwd}"</span> <span style="color: rgba(0, 0, 255, 1)">/&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">bean</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>

<span style="color: rgba(0, 128, 0, 1)">&lt;!--</span><span style="color: rgba(0, 128, 0, 1)">创建一个sql会话工厂bean，指定数据源 </span><span style="color: rgba(0, 128, 0, 1)">--&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">bean </span><span style="color: rgba(255, 0, 0, 1)">id</span><span style="color: rgba(0, 0, 255, 1)">="sqlSessionFactory"</span><span style="color: rgba(255, 0, 0, 1)"> class</span><span style="color: rgba(0, 0, 255, 1)">="org.mybatis.spring.SqlSessionFactoryBean"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
    <span style="color: rgba(0, 128, 0, 1)">&lt;!--</span><span style="color: rgba(0, 128, 0, 1)"> 指定数据源 </span><span style="color: rgba(0, 128, 0, 1)">--&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="dataSource"</span><span style="color: rgba(255, 0, 0, 1)"> ref</span><span style="color: rgba(0, 0, 255, 1)">="jdbcDataSource"</span> <span style="color: rgba(0, 0, 255, 1)">/&gt;</span>
    <span style="color: rgba(0, 128, 0, 1)">&lt;!--</span><span style="color: rgba(0, 128, 0, 1)">类型别名包，默认引入com.zhangguo.Spring61.entities下的所有类 </span><span style="color: rgba(0, 128, 0, 1)">--&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="typeAliasesPackage"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="com.zhangguo.Spring61.entities"</span><span style="color: rgba(0, 0, 255, 1)">&gt;&lt;/</span><span style="color: rgba(128, 0, 0, 1)">property</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
    <span style="color: rgba(0, 128, 0, 1)">&lt;!--</span><span style="color: rgba(0, 128, 0, 1)">指定sql映射xml文件的路径 </span><span style="color: rgba(0, 128, 0, 1)">--&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="mapperLocations"</span><span style="color: rgba(255, 0, 0, 1)">
        value</span><span style="color: rgba(0, 0, 255, 1)">="classpath:com/zhangguo/Spring61/mapping/*Mapper.xml"</span><span style="color: rgba(0, 0, 255, 1)">&gt;&lt;/</span><span style="color: rgba(128, 0, 0, 1)">property</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">bean</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>

<span style="color: rgba(0, 128, 0, 1)">&lt;!--</span><span style="color: rgba(0, 128, 0, 1)">自动扫描映射接口 </span><span style="color: rgba(0, 128, 0, 1)">--&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">bean </span><span style="color: rgba(255, 0, 0, 1)">class</span><span style="color: rgba(0, 0, 255, 1)">="org.mybatis.spring.mapper.MapperScannerConfigurer"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
    <span style="color: rgba(0, 128, 0, 1)">&lt;!--</span><span style="color: rgba(0, 128, 0, 1)"> 指定sql会话工厂，在上面配置过的 </span><span style="color: rgba(0, 128, 0, 1)">--&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="sqlSessionFactoryBeanName"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="sqlSessionFactory"</span><span style="color: rgba(0, 0, 255, 1)">&gt;&lt;/</span><span style="color: rgba(128, 0, 0, 1)">property</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
    <span style="color: rgba(0, 128, 0, 1)">&lt;!--</span><span style="color: rgba(0, 128, 0, 1)"> 指定基础包，即自动扫描com.zhangguo.Spring61.mapping这个包以及它的子包下的所有映射接口类 </span><span style="color: rgba(0, 128, 0, 1)">--&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="basePackage"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="com.zhangguo.Spring61.mapping"</span><span style="color: rgba(0, 0, 255, 1)">&gt;&lt;/</span><span style="color: rgba(128, 0, 0, 1)">property</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">bean</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>

<span style="color: rgba(0, 128, 0, 1)">&lt;!--</span><span style="color: rgba(0, 128, 0, 1)"> 创建一个sqlSession对象 </span><span style="color: rgba(0, 128, 0, 1)">--&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">bean </span><span style="color: rgba(255, 0, 0, 1)">id</span><span style="color: rgba(0, 0, 255, 1)">="sqlSession"</span><span style="color: rgba(255, 0, 0, 1)"> class</span><span style="color: rgba(0, 0, 255, 1)">="org.mybatis.spring.SqlSessionTemplate"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">constructor-arg </span><span style="color: rgba(255, 0, 0, 1)">index</span><span style="color: rgba(0, 0, 255, 1)">="0"</span><span style="color: rgba(255, 0, 0, 1)"> ref</span><span style="color: rgba(0, 0, 255, 1)">="sqlSessionFactory"</span> <span style="color: rgba(0, 0, 255, 1)">/&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">bean</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>

<span style="color: rgba(0, 128, 0, 1)">&lt;!--</span><span style="color: rgba(0, 128, 0, 1)">自动扫描组件 </span><span style="color: rgba(0, 128, 0, 1)">--&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">context:component-scan </span><span style="color: rgba(255, 0, 0, 1)">base-package</span><span style="color: rgba(0, 0, 255, 1)">="com.zhangguo.Spring61"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">context:exclude-filter </span><span style="color: rgba(255, 0, 0, 1)">type</span><span style="color: rgba(0, 0, 255, 1)">="aspectj"</span><span style="color: rgba(255, 0, 0, 1)"> expression</span><span style="color: rgba(0, 0, 255, 1)">="com.zhangguo.Spring61.dao.*"</span><span style="color: rgba(0, 0, 255, 1)">/&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">context:component-scan</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">aop:aspectj-autoproxy </span><span style="color: rgba(255, 0, 0, 1)">proxy-target-class</span><span style="color: rgba(0, 0, 255, 1)">="true"</span><span style="color: rgba(0, 0, 255, 1)">&gt;&lt;/</span><span style="color: rgba(128, 0, 0, 1)">aop:aspectj-autoproxy</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>

</beans>

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运行结果：

2.2、实现接口 ApplicationContextAware

当一个类实现了 org.springframework.context.ApplicationContextAware 接口时且实现该接口的类被 Spring 容器管理，则 Spring 容器会自动意识到需要调用接口中的方法 setApplicationContext 设置当前的 Spring 上下文。通俗说实现这个接口可以方便获得 Spring 上下文。该接口如下：

/*
 * Copyright 2002-2012 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.springframework.context;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.Aware;
/**


Interface to be implemented by any object that wishes to be notified


of the {@link ApplicationContext} that it runs in.



<p>Implementing this interface makes sense for example when an object


requires access to a set of collaborating beans. Note that configuration


via bean references is preferable to implementing this interface just


for bean lookup purposes.



<p>This interface can also be implemented if an object needs access to file


resources, i.e. wants to call {@code getResource}, wants to publish


an application event, or requires access to the MessageSource. However,


it is preferable to implement the more specific {@link ResourceLoaderAware},


{@link ApplicationEventPublisherAware} or {@link MessageSourceAware} interface


in such a specific scenario.



<p>Note that file resource dependencies can also be exposed as bean properties


of type {@link org.springframework.core.io.Resource}, populated via Strings


with automatic type conversion by the bean factory. This removes the need


for implementing any callback interface just for the purpose of accessing


a specific file resource.



<p>{@link org.springframework.context.support.ApplicationObjectSupport} is a


convenience base class for application objects, implementing this interface.



<p>For a list of all bean lifecycle methods, see the


{@link org.springframework.beans.factory.BeanFactory BeanFactory javadocs}.



@author Rod Johnson


@author Juergen Hoeller


@author Chris Beams


@see ResourceLoaderAware


@see ApplicationEventPublisherAware


@see MessageSourceAware


@see org.springframework.context.support.ApplicationObjectSupport


@see org.springframework.beans.factory.BeanFactoryAware
*/
public interface ApplicationContextAware extends Aware {
/**

Set the ApplicationContext that this object runs in.
Normally this call will be used to initialize the object.
<p>Invoked after population of normal bean properties but before an init callback such
as {@link org.springframework.beans.factory.InitializingBean#afterPropertiesSet()}
or a custom init-method. Invoked after {@link ResourceLoaderAware#setResourceLoader},
{@link ApplicationEventPublisherAware#setApplicationEventPublisher} and
{@link MessageSourceAware}, if applicable.
@param applicationContext the ApplicationContext object to be used by this object
@throws ApplicationContextException in case of context initialization errors
@throws BeansException if thrown by application context methods
@see org.springframework.beans.factory.BeanInitializationException
*/
void setApplicationContext(ApplicationContext applicationContext) throws BeansException;



}

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为了达到目的，我们现在创建一个名为 CtxUtil.java 的类，实现该接口，代如下：

package com.zhangguo.Spring61.action;
import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;
@Component
public class CtxUtil implements ApplicationContextAware {
</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">static</span><span style="color: rgba(0, 0, 0, 1)"> ApplicationContext springCtx;

@Override
</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span> setApplicationContext(ApplicationContext applicationContext) <span style="color: rgba(0, 0, 255, 1)">throws</span><span style="color: rgba(0, 0, 0, 1)"> BeansException {
    springCtx</span>=<span style="color: rgba(0, 0, 0, 1)">applicationContext;
}

</span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)">根据名称获得容器中的bean</span>
<span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">static</span><span style="color: rgba(0, 0, 0, 1)"> Object getBean(String name){
    </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> springCtx.getBean(name);
}

</span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)">根据类型获得容器中的bean</span>
<span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">static</span> &lt;T&gt; T getBean(Class&lt;T&gt;<span style="color: rgba(0, 0, 0, 1)"> clazz){
    </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> springCtx.getBean(clazz);
}

}

为了让 Spring 容器在加载时能扫描到该类，我们在类上注解了 @Component；其实也可以直接在 ApplicationContext.xml 中新增一个 bean，如下所示：

    <bean id="ctxUtil" class="com.zhangguo.Spring61.action.CtxUtil"></bean>
<span style="color: rgba(0, 128, 0, 1)">&lt;!--</span><span style="color: rgba(0, 128, 0, 1)">自动扫描组件 </span><span style="color: rgba(0, 128, 0, 1)">--&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">context:component-scan </span><span style="color: rgba(255, 0, 0, 1)">base-package</span><span style="color: rgba(0, 0, 255, 1)">="com.zhangguo.Spring61"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">context:exclude-filter </span><span style="color: rgba(255, 0, 0, 1)">type</span><span style="color: rgba(0, 0, 255, 1)">="aspectj"</span><span style="color: rgba(255, 0, 0, 1)"> expression</span><span style="color: rgba(0, 0, 255, 1)">="com.zhangguo.Spring61.dao.*"</span><span style="color: rgba(0, 0, 255, 1)">/&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">context:component-scan</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span></pre>

测试代码如下：

package com.zhangguo.Spring61.action;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.support.WebApplicationContextUtils;
import com.zhangguo.Spring61.service.BookTypeService;
@WebServlet("/BookTypeSize.do")
public class BookTypeSize extends HttpServlet {
private static final long serialVersionUID = 1L;
 BookTypeService bookTypeService;
 
@Override
</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span> init() <span style="color: rgba(0, 0, 255, 1)">throws</span><span style="color: rgba(0, 0, 0, 1)"> ServletException {
  </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)">从容器中获得bean</span>
  bookTypeService=CtxUtil.getBean(BookTypeService.<span style="color: rgba(0, 0, 255, 1)">class</span><span style="color: rgba(0, 0, 0, 1)">);
}

</span><span style="color: rgba(0, 0, 255, 1)">protected</span> <span style="color: rgba(0, 0, 255, 1)">void</span> doGet(HttpServletRequest request, HttpServletResponse response) <span style="color: rgba(0, 0, 255, 1)">throws</span><span style="color: rgba(0, 0, 0, 1)"> ServletException, IOException {
    PrintWriter writer</span>=<span style="color: rgba(0, 0, 0, 1)">response.getWriter();
    writer.print(bookTypeService.getAllBookTypes().size());
}

</span><span style="color: rgba(0, 0, 255, 1)">protected</span> <span style="color: rgba(0, 0, 255, 1)">void</span> doPost(HttpServletRequest request, HttpServletResponse response) <span style="color: rgba(0, 0, 255, 1)">throws</span><span style="color: rgba(0, 0, 0, 1)"> ServletException, IOException {
    doGet(request, response);
}

}

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运行结果同 2.1。

三、基于注解的声明式事务管理配置

MyBatis-Spring 利用了存在于 Spring 中的 DataSourceTransactionManager 管理事务。

一旦 Spring 的 PlatformTransactionManager 配置好了, 你可以在 Spring 中以你通常的做法来配置事务。@Transactional 注解和 AOP 方式的配置都是支持的。在事务处理期间, 一个单独的 SqlSession 对象将会被创建和使用。当事务完成时, 这个 session 会以合适的方式提交或回滚。一旦事务创建之后,MyBatis-Spring 将会透明的管理事务。在你的 DAO 类中就不需要额外的代码了。

我们先使用一个简单的示例，证明没有事务时的状态：

        PrintWriter writer=response.getWriter();
        BookType entity1=new BookType();
        entity1.setTypeName("中国文学");
    BookType entity2</span>=<span style="color: rgba(0, 0, 255, 1)">new</span><span style="color: rgba(0, 0, 0, 1)"> BookType();
    entity1.setTypeName(</span>"外国文学");  <span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)">请注意这是是entity1</span>
    writer.print(bookTypeService.addDouble(entity1, entity2));</pre>

当运行时会发现有异常，因为 entity2 的 typeName 属性是 null，报异常了；按照事务的特性两条记录要么都添加成功要么都添加不成功。但查看数据库会发现，有一个对象的数据被添加成功了，另一个则失败了，这不符合原子特性。

为了解决上面的问题，我们引入 Spring 中的事务与 MyBatis-Spring 的事务管理。一定要记得添加 Spring-tx.jar 的依赖。修改 ApplicationContext.xml 如下所示：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xmlns:p="http://www.springframework.org/schema/p"
    xmlns:aop="http://www.springframework.org/schema/aop" 
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:tx="http://www.springframework.org/schema/tx" 
    xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context-4.3.xsd
        http://www.springframework.org/schema/aop
        http://www.springframework.org/schema/aop/spring-aop-4.3.xsd
        http://www.springframework.org/schema/tx
        http://www.springframework.org/schema/tx/spring-tx-4.3.xsd">
<span style="color: rgba(0, 128, 0, 1)">&lt;!--</span><span style="color: rgba(0, 128, 0, 1)">属性占位文件引入，可以通过${属性名}获得属性文件中的内容 </span><span style="color: rgba(0, 128, 0, 1)">--&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">context:property-placeholder </span><span style="color: rgba(255, 0, 0, 1)">location</span><span style="color: rgba(0, 0, 255, 1)">="classpath:db.properties"</span> <span style="color: rgba(0, 0, 255, 1)">/&gt;</span>

<span style="color: rgba(0, 128, 0, 1)">&lt;!--</span><span style="color: rgba(0, 128, 0, 1)">定义一个jdbc数据源，创建一个驱动管理数据源的bean </span><span style="color: rgba(0, 128, 0, 1)">--&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">bean </span><span style="color: rgba(255, 0, 0, 1)">id</span><span style="color: rgba(0, 0, 255, 1)">="jdbcDataSource"</span><span style="color: rgba(255, 0, 0, 1)"> class</span><span style="color: rgba(0, 0, 255, 1)">="com.mchange.v2.c3p0.ComboPooledDataSource"</span><span style="color: rgba(255, 0, 0, 1)">
    destroy-method</span><span style="color: rgba(0, 0, 255, 1)">="close"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="driverClass"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="${jdbc.driver}"</span> <span style="color: rgba(0, 0, 255, 1)">/&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="jdbcUrl"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="${jdbc.url}"</span> <span style="color: rgba(0, 0, 255, 1)">/&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="user"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="${jdbc.uid}"</span> <span style="color: rgba(0, 0, 255, 1)">/&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="password"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="${jdbc.pwd}"</span> <span style="color: rgba(0, 0, 255, 1)">/&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="acquireIncrement"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="5"</span><span style="color: rgba(0, 0, 255, 1)">&gt;&lt;/</span><span style="color: rgba(128, 0, 0, 1)">property</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="initialPoolSize"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="10"</span><span style="color: rgba(0, 0, 255, 1)">&gt;&lt;/</span><span style="color: rgba(128, 0, 0, 1)">property</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="minPoolSize"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="5"</span><span style="color: rgba(0, 0, 255, 1)">&gt;&lt;/</span><span style="color: rgba(128, 0, 0, 1)">property</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="maxPoolSize"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="20"</span><span style="color: rgba(0, 0, 255, 1)">&gt;&lt;/</span><span style="color: rgba(128, 0, 0, 1)">property</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">bean</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>

<span style="color: rgba(0, 128, 0, 1)">&lt;!--</span><span style="color: rgba(0, 128, 0, 1)">定义一个jdbc数据源，创建一个驱动管理数据源的bean </span><span style="color: rgba(0, 128, 0, 1)">--&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">bean </span><span style="color: rgba(255, 0, 0, 1)">id</span><span style="color: rgba(0, 0, 255, 1)">="jdbcDataSourceBak"</span><span style="color: rgba(255, 0, 0, 1)">
    class</span><span style="color: rgba(0, 0, 255, 1)">="org.springframework.jdbc.datasource.DriverManagerDataSource"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="driverClassName"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="${jdbc.driver}"</span> <span style="color: rgba(0, 0, 255, 1)">/&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="url"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="${jdbc.url}"</span> <span style="color: rgba(0, 0, 255, 1)">/&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="username"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="${jdbc.uid}"</span> <span style="color: rgba(0, 0, 255, 1)">/&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="password"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="${jdbc.pwd}"</span> <span style="color: rgba(0, 0, 255, 1)">/&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">bean</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>

<span style="color: rgba(0, 128, 0, 1)">&lt;!--</span><span style="color: rgba(0, 128, 0, 1)">创建一个sql会话工厂bean，指定数据源 </span><span style="color: rgba(0, 128, 0, 1)">--&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">bean </span><span style="color: rgba(255, 0, 0, 1)">id</span><span style="color: rgba(0, 0, 255, 1)">="sqlSessionFactory"</span><span style="color: rgba(255, 0, 0, 1)"> class</span><span style="color: rgba(0, 0, 255, 1)">="org.mybatis.spring.SqlSessionFactoryBean"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
    <span style="color: rgba(0, 128, 0, 1)">&lt;!--</span><span style="color: rgba(0, 128, 0, 1)"> 指定数据源 </span><span style="color: rgba(0, 128, 0, 1)">--&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="dataSource"</span><span style="color: rgba(255, 0, 0, 1)"> ref</span><span style="color: rgba(0, 0, 255, 1)">="jdbcDataSource"</span> <span style="color: rgba(0, 0, 255, 1)">/&gt;</span>
    <span style="color: rgba(0, 128, 0, 1)">&lt;!--</span><span style="color: rgba(0, 128, 0, 1)">类型别名包，默认引入com.zhangguo.Spring61.entities下的所有类 </span><span style="color: rgba(0, 128, 0, 1)">--&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="typeAliasesPackage"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="com.zhangguo.Spring61.entities"</span><span style="color: rgba(0, 0, 255, 1)">&gt;&lt;/</span><span style="color: rgba(128, 0, 0, 1)">property</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
    <span style="color: rgba(0, 128, 0, 1)">&lt;!--</span><span style="color: rgba(0, 128, 0, 1)">指定sql映射xml文件的路径 </span><span style="color: rgba(0, 128, 0, 1)">--&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="mapperLocations"</span><span style="color: rgba(255, 0, 0, 1)">
        value</span><span style="color: rgba(0, 0, 255, 1)">="classpath:com/zhangguo/Spring61/mapping/*Mapper.xml"</span><span style="color: rgba(0, 0, 255, 1)">&gt;&lt;/</span><span style="color: rgba(128, 0, 0, 1)">property</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">bean</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>

<span style="color: rgba(0, 128, 0, 1)">&lt;!--</span><span style="color: rgba(0, 128, 0, 1)">自动扫描映射接口 </span><span style="color: rgba(0, 128, 0, 1)">--&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">bean </span><span style="color: rgba(255, 0, 0, 1)">class</span><span style="color: rgba(0, 0, 255, 1)">="org.mybatis.spring.mapper.MapperScannerConfigurer"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
    <span style="color: rgba(0, 128, 0, 1)">&lt;!--</span><span style="color: rgba(0, 128, 0, 1)"> 指定sql会话工厂，在上面配置过的 </span><span style="color: rgba(0, 128, 0, 1)">--&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="sqlSessionFactoryBeanName"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="sqlSessionFactory"</span><span style="color: rgba(0, 0, 255, 1)">&gt;&lt;/</span><span style="color: rgba(128, 0, 0, 1)">property</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
    <span style="color: rgba(0, 128, 0, 1)">&lt;!--</span><span style="color: rgba(0, 128, 0, 1)"> 指定基础包，即自动扫描com.zhangguo.Spring61.mapping这个包以及它的子包下的所有映射接口类 </span><span style="color: rgba(0, 128, 0, 1)">--&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">property </span><span style="color: rgba(255, 0, 0, 1)">name</span><span style="color: rgba(0, 0, 255, 1)">="basePackage"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="com.zhangguo.Spring61.mapping"</span><span style="color: rgba(0, 0, 255, 1)">&gt;&lt;/</span><span style="color: rgba(128, 0, 0, 1)">property</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">bean</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>

<span style="color: rgba(0, 128, 0, 1)">&lt;!--</span><span style="color: rgba(0, 128, 0, 1)"> 创建一个sqlSession对象 </span><span style="color: rgba(0, 128, 0, 1)">--&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">bean </span><span style="color: rgba(255, 0, 0, 1)">id</span><span style="color: rgba(0, 0, 255, 1)">="sqlSession"</span><span style="color: rgba(255, 0, 0, 1)"> class</span><span style="color: rgba(0, 0, 255, 1)">="org.mybatis.spring.SqlSessionTemplate"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">constructor-arg </span><span style="color: rgba(255, 0, 0, 1)">index</span><span style="color: rgba(0, 0, 255, 1)">="0"</span><span style="color: rgba(255, 0, 0, 1)"> ref</span><span style="color: rgba(0, 0, 255, 1)">="sqlSessionFactory"</span> <span style="color: rgba(0, 0, 255, 1)">/&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">bean</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>

<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">bean </span><span style="color: rgba(255, 0, 0, 1)">id</span><span style="color: rgba(0, 0, 255, 1)">="ctxUtil"</span><span style="color: rgba(255, 0, 0, 1)"> class</span><span style="color: rgba(0, 0, 255, 1)">="com.zhangguo.Spring61.action.CtxUtil"</span><span style="color: rgba(0, 0, 255, 1)">&gt;&lt;/</span><span style="color: rgba(128, 0, 0, 1)">bean</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>

    <!--声明式事务管理 -->
<bean id="txManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
<property name="dataSource" ref="jdbcDataSource"></property>
</bean>
<!--声明支持使用注解管理事务 -->
<tx:annotation-driven transaction-manager="txManager"/>
<span style="color: rgba(0, 128, 0, 1)">&lt;!--</span><span style="color: rgba(0, 128, 0, 1)">自动扫描组件 </span><span style="color: rgba(0, 128, 0, 1)">--&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">context:component-scan </span><span style="color: rgba(255, 0, 0, 1)">base-package</span><span style="color: rgba(0, 0, 255, 1)">="com.zhangguo.Spring61"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
    <span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">context:exclude-filter </span><span style="color: rgba(255, 0, 0, 1)">type</span><span style="color: rgba(0, 0, 255, 1)">="aspectj"</span><span style="color: rgba(255, 0, 0, 1)"> expression</span><span style="color: rgba(0, 0, 255, 1)">="com.zhangguo.Spring61.dao.*"</span><span style="color: rgba(0, 0, 255, 1)">/&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">context:component-scan</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">aop:aspectj-autoproxy </span><span style="color: rgba(255, 0, 0, 1)">proxy-target-class</span><span style="color: rgba(0, 0, 255, 1)">="true"</span><span style="color: rgba(0, 0, 255, 1)">&gt;&lt;/</span><span style="color: rgba(128, 0, 0, 1)">aop:aspectj-autoproxy</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>

</beans>

请注意，加粗字体的部分是新增的。修改后的 BookTypeDAO 接口如下：

package com.zhangguo.Spring61.mapping;
import java.util.List;
import com.zhangguo.Spring61.entities.BookType;
/**

图书类型数据访问接口


/
public interface BookTypeDAO {
/
* 获得所有图书类型
*/
public List<BookType> getAllBookTypes();
</span><span style="color: rgba(0, 128, 0, 1)">/**</span><span style="color: rgba(0, 128, 0, 1)">
 * 添加新的图书类型
 </span><span style="color: rgba(0, 128, 0, 1)">*/</span>
<span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> add(BookType entity);

}

修改后的 BookTypeMapper.xml 映射文件如下：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<!--命名空间应该是对应接口的包名 + 类名 -->
<mapper namespace="com.zhangguo.Spring61.mapping.BookTypeDAO">
    <!--id 应该是接口中的方法，结果类型如没有配置别名则应该使用全名称 -->
    <select id="getAllBookTypes" resultType="BookType">
        select id,typeName from booktypes
    </select>
<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">insert </span><span style="color: rgba(255, 0, 0, 1)">id</span><span style="color: rgba(0, 0, 255, 1)">="add"</span><span style="color: rgba(255, 0, 0, 1)"> parameterType</span><span style="color: rgba(0, 0, 255, 1)">="BookType"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span><span style="color: rgba(0, 0, 0, 1)">
    insert into booktypes(typeName) values(#{typeName})
</span><span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">insert</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>

</mapper>

修改后的 BookTypeService 类如下：

package com.zhangguo.Spring61.service;
import java.util.List;
import javax.annotation.Resource;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import com.zhangguo.Spring61.entities.BookType;
import com.zhangguo.Spring61.mapping.BookTypeDAO;
/*


图书类型服务
*/
@Service
public class BookTypeService {
@Resource
BookTypeDAO bookTypeDAO;
public List<BookType> getAllBookTypes() {
System.err.println("一些被省去的业务");
return bookTypeDAO.getAllBookTypes();
}
@Transactional
public int addDouble(BookType entity1,BookType entity2){
int rows=0;
rows+=bookTypeDAO.add(entity1);
rows+=bookTypeDAO.add(entity2);
return rows;
}
}

在方法 addDouble 上增加了一个注解 @Transactional，用于显式声明该方法需要事务处理，如果把该注解移除则不会拥有事务特性。

测试的 Servlet 代码如下：

package com.zhangguo.Spring61.action;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.support.WebApplicationContextUtils;
import com.zhangguo.Spring61.entities.BookType;
import com.zhangguo.Spring61.service.BookTypeService;
@WebServlet("/BookTypeAdd.do")
public class BookTypeAdd extends HttpServlet {
private static final long serialVersionUID = 1L;
 BookTypeService bookTypeService;
 
@Override
</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span> init() <span style="color: rgba(0, 0, 255, 1)">throws</span><span style="color: rgba(0, 0, 0, 1)"> ServletException {
  </span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)">从容器中获得bean</span>
  bookTypeService=CtxUtil.getBean(BookTypeService.<span style="color: rgba(0, 0, 255, 1)">class</span><span style="color: rgba(0, 0, 0, 1)">);
}

</span><span style="color: rgba(0, 0, 255, 1)">protected</span> <span style="color: rgba(0, 0, 255, 1)">void</span> doGet(HttpServletRequest request, HttpServletResponse response) <span style="color: rgba(0, 0, 255, 1)">throws</span><span style="color: rgba(0, 0, 0, 1)"> ServletException, IOException {
    PrintWriter writer</span>=<span style="color: rgba(0, 0, 0, 1)">response.getWriter();
    BookType entity1</span>=<span style="color: rgba(0, 0, 255, 1)">new</span><span style="color: rgba(0, 0, 0, 1)"> BookType();
    entity1.setTypeName(</span>"量子力学"<span style="color: rgba(0, 0, 0, 1)">);
    
    BookType entity2</span>=<span style="color: rgba(0, 0, 255, 1)">new</span><span style="color: rgba(0, 0, 0, 1)"> BookType();
    entity1.setTypeName(</span>"天体物理");  <span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)">请注意这是是entity1，entity2的typeName属性为空</span>

        writer.print(bookTypeService.addDouble(entity1, entity2));
}
</span><span style="color: rgba(0, 0, 255, 1)">protected</span> <span style="color: rgba(0, 0, 255, 1)">void</span> doPost(HttpServletRequest request, HttpServletResponse response) <span style="color: rgba(0, 0, 255, 1)">throws</span><span style="color: rgba(0, 0, 0, 1)"> ServletException, IOException {
    doGet(request, response);
}

}

entity2 因为没有 typeName 属性，添加时会异常，有事务存在，则数据库并没有变化，entity1 与 entity2 都未添加到数据库中。

除了使用声明式事务管理，也可以使用 AOP 进行事务拦截，参考代码如下：

    <!-- 拦截器方式配置事物 -->
    <tx:advice id="transactionAdvice" transaction-manager="transactionManager">
        <tx:attributes>
            <tx:method name="add*" propagation="REQUIRED" />
            <tx:method name="append*" propagation="REQUIRED" />
            <tx:method name="insert*" propagation="REQUIRED" />
            <tx:method name="save*" propagation="REQUIRED" />
            <tx:method name="update*" propagation="REQUIRED" />
            <tx:method name="modify*" propagation="REQUIRED" />
            <tx:method name="edit*" propagation="REQUIRED" />
            <tx:method name="delete*" propagation="REQUIRED" />
            <tx:method name="remove*" propagation="REQUIRED" />
            <tx:method name="repair" propagation="REQUIRED" />
            <tx:method name="delAndRepair" propagation="REQUIRED" />
            <tx:method name="get*" propagation="SUPPORTS" />
            <tx:method name="find*" propagation="SUPPORTS" />
            <tx:method name="load*" propagation="SUPPORTS" />
            <tx:method name="search*" propagation="SUPPORTS" />
            <tx:method name="datagrid*" propagation="SUPPORTS" />
            <tx:method name="*" propagation="SUPPORTS" />
        </tx:attributes>
    </tx:advice>
    <aop:config>
        <aop:pointcut id="transactionPointcut" expression="execution(* com.service..*Impl.*(..))" />
        <aop:advisor pointcut-ref="transactionPointcut" advice-ref="transactionAdvice" />
    </aop:config>

小结：声明式事务管理需要根据实际情况编码注解方法要不要事务处理，拦截方式配置事务则是根据方法名统一处理，一般查询是不需要事务参与的。在上面的配置中 REQUIRED 则表示需要事务支持，而 SUPPORTS 则不需要事务支持。

四、示例下载

示例下载

Spring学习总结（五）——Spring整合MyBatis（Maven+MySQL）二

一、在 Web 项目中启动 Spring 容器

1.1、使用监听器启动 Spring 容器

1.2、使用 Servlet 方式启动 Spring 容器

二、获取 ApplicationContext 实例

2.1、使用工具类 WebApplicationContextUtils 获得 Spring 容器

2.2、实现接口 ApplicationContextAware

三、基于注解的声明式事务管理配置

四、示例下载

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Spring学习总结（五）——Spring整合MyBatis（Maven+MySQL）二