SpringBoot+MyBatis+Mysql 详细示例
SpringBoot 与 MyBatis 整合，底层数据库为 mysql 的使用示例
项目下载链接：https://github.com/DFX339/bootdemo.git
新建 maven 项目，web 项目，项目名为 bootdemo
项目结构目录如下: 还有个 pom.xml 文件没有在截图里面
项目需要编写的文件主要有：
项目启动类： Application.java ServletInitializer.java
前端控制器类：UserController.java
业务层的接口与实现类：UserIservice.java UserService.java
Mybatis 的接口： UserMapper.java
接口对应的 mapper 文件：UserMapper.xml
实体类：User.java
maven 项目的配置文件： pom.xml
（1）编写实体类 User.java
package smm.springboot_ftl.bean;/**
- User 实体类
- @author Administrator
*/
public class User {</span><span style="color: rgba(0, 0, 255, 1)">private</span> <span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> id; </span><span style="color: rgba(0, 0, 255, 1)">private</span><span style="color: rgba(0, 0, 0, 1)"> String username; </span><span style="color: rgba(0, 0, 255, 1)">private</span><span style="color: rgba(0, 0, 0, 1)"> String password; </span><span style="color: rgba(0, 0, 255, 1)">private</span> <span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> age; </span><span style="color: rgba(0, 0, 255, 1)">public</span><span style="color: rgba(0, 0, 0, 1)"> User(){} </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)"> getId() { </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> id; } </span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span> setId(<span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> id) { </span><span style="color: rgba(0, 0, 255, 1)">this</span>.id =<span style="color: rgba(0, 0, 0, 1)"> id; } </span><span style="color: rgba(0, 0, 255, 1)">public</span><span style="color: rgba(0, 0, 0, 1)"> String getUsername() { </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> username; } </span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span><span style="color: rgba(0, 0, 0, 1)"> setUsername(String username) { </span><span style="color: rgba(0, 0, 255, 1)">this</span>.username =<span style="color: rgba(0, 0, 0, 1)"> username; } </span><span style="color: rgba(0, 0, 255, 1)">public</span><span style="color: rgba(0, 0, 0, 1)"> String getPassword() { </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> password; } </span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span><span style="color: rgba(0, 0, 0, 1)"> setPassword(String password) { </span><span style="color: rgba(0, 0, 255, 1)">this</span>.password =<span style="color: rgba(0, 0, 0, 1)"> password; } </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)"> getAge() { </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> age; } </span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span> setAge(<span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> age) { </span><span style="color: rgba(0, 0, 255, 1)">this</span>.age =<span style="color: rgba(0, 0, 0, 1)"> age; }}
（2）登录 mysql 数据库，新建数据库 springboot_mybatis（数据库名）
新建表 user（表名），表的字段如图所示
（3）编写持久层接口： UserMapper.java (定义操作数据库的方法) 这里切记要用 @Mapper 注解标识
package smm.springboot_ftl.mapper;import org.apache.ibatis.annotations.Mapper;
import smm.springboot_ftl.bean.User;
@Mapper
public interface UserMapper {</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span><span style="color: rgba(0, 0, 0, 1)"> insert(User user); </span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span><span style="color: rgba(0, 0, 0, 1)"> update(User user); </span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span> delete(<span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> id); </span><span style="color: rgba(0, 0, 255, 1)">public</span> User find(<span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> id);}
（4）编写持久层接口对应的 mapper.xml 文件： UserMapper.xml （编写增删改查对应的 sql 语句）
存储位置： src/main/resources/mapper
<?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"><!-- 指定工作空间，要与接口名相同，源代码没有去看，猜测应该是通过 "这里的 namespace. 下边方法的 id" 来定位方法的 -->
<mapper namespace="smm.springboot_ftl.mapper.UserMapper"><!-- insert user --> <insert id = "insert" parameterType="smm.springboot_ftl.bean.User"><span style="color: rgba(0, 0, 0, 1)"> INSERT INTO USER(ID,USERNAME,PASSWORD,AGE) VALUES(#{id},#{username},#{password},#{age}); </span></insert> <!-- update user --> <update id="update" parameterType="smm.springboot_ftl.bean.User"><span style="color: rgba(0, 0, 0, 1)"> UPDATE USER SET USERNAME</span>=#{username} , PASSWORD=#{password} , AGE = #{age} WHERE ID=<span style="color: rgba(0, 0, 0, 1)">#{id} </span></update> <!-- find user --> <select id="find" parameterType="int" resultType="smm.springboot_ftl.bean.User"><span style="color: rgba(0, 0, 0, 1)"> SELECT ID,USERNAME,PASSWORD,AGE FROM USER WHERE ID</span>=#{0<span style="color: rgba(0, 0, 0, 1)">} </span></select> <!-- delete user --> <delete id="delete" parameterType="int"><span style="color: rgba(0, 0, 0, 1)"> DELETE FROM USER WHERE ID</span>=#{0<span style="color: rgba(0, 0, 0, 1)">} </span></delete></mapper>
（5）编写业务层接口： UserIService.java
package smm.springboot_ftl.service;import org.springframework.stereotype.Component;
import smm.springboot_ftl.bean.User;
public interface UserIService {
</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span><span style="color: rgba(0, 0, 0, 1)"> insert(User user);<br></span></pre>public void update(User user) ； public User find(int id)； public void delete(int id)；}
（6）编写业务层接口的实现类：UserService.java （切记要使用 @Service("userService") 类标识类，表示这是 service）
@ComponentScan({"ssm.springboot_ftl.mapper"})：是为了找到对应的 UserMapper 对象
package smm.springboot_ftl.service;import javax.annotation.Resource;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.stereotype.Component;
import org.springframework.stereotype.Service;import smm.springboot_ftl.bean.User;
import smm.springboot_ftl.mapper.UserMapper;@ComponentScan({"ssm.springboot_ftl.mapper"})
@Service("userService")
public class UserService implements UserIService{@Resource </span><span style="color: rgba(0, 0, 255, 1)">private</span><span style="color: rgba(0, 0, 0, 1)"> UserMapper userMapper; @Override </span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span><span style="color: rgba(0, 0, 0, 1)"> insert(User user) { userMapper.insert(user); } </span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span><span style="color: rgba(0, 0, 0, 1)"> update(User user) { userMapper.update(user); } </span><span style="color: rgba(0, 0, 255, 1)">public</span> User find(<span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> id) { </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> userMapper.find(id); } </span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">void</span> delete(<span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> id){ userMapper.delete(id); }}
（7）编写前端控制器类： UserController.java
@RestController 标识这个类，返回的结果为 Json 字符串。
@RestController 注解，相当于 @Controller+@ResponseBody 两个注解的结合，返回 json 数据不需要在方法前面加 @ResponseBody 注解了，但使用@RestController 这个注解，就不能返回 jsp,html 页面，视图解析器无法解析 jsp,html 页面
如果需要返回数据到 jsp 或者 html 页面，则使用 @Controller 注解。这里推荐使用 @Controller 注解，因为需要直接返回数据的时候可以增加 @ResponseBody 注解
@ComponentScan({"smm.springboot_ftl.service"}) ：标识业务层的类，用来找到业务层对象，smm.springboot_ftl.service是业务类的路径
@MapperScan("smm.springboot_ftl.mapper") ：标识持久层 mapper 接口，用来找到 mapper 对象， smm.springboot_ftl.mapper 是接口的路径
这三个注解都不能少！！！ 少了 SpringBoot 就无法正常启动了！！
package smm.springboot_ftl.action;import java.util.Map;
import javax.annotation.Resource;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.servlet.ModelAndView;import smm.springboot_ftl.bean.User;
import smm.springboot_ftl.service.UserService;
/**
在定义一个 Rest 接口时，我们通常会使用 GET，POST，PUT，DELETE 几种方式来完成我们所需要进行 CRUD 的一些操作，
我们在这里罗列和教大家在实际开发中的使用，一些基本概念我们就不再赘述，例如使用 POST 的优缺点，可使用参数的大小限制等地：
GET：一般用于查询数据，不办函数据的更新以及插入操作。由于明文传输的关系，我们一般用来获取一些无关用户的信息。
POST：一般用于数据的插入操作，也是使用最多的传输方式，但是在 H5 调用时会有跨域的问题，一般使用 JSONP 来解决。
PUT：我们使用 PUT 方式来对数据进行更新操作。
DELETE：用于数据删除，注意在数据库内是逻辑删除（改变数据状态，用户不再查询得到，但还保留在数据库内）还是物理删除（真删了）。
@author Administrator
*/
@RestController
@ComponentScan({"smm.springboot_ftl.service"})
@MapperScan("smm.springboot_ftl.mapper")
public class UserController {@Resource </span><span style="color: rgba(0, 0, 255, 1)">private</span><span style="color: rgba(0, 0, 0, 1)"> UserService userService; @RequestMapping(</span>"/say"<span style="color: rgba(0, 0, 0, 1)">) </span><span style="color: rgba(0, 0, 255, 1)">public</span><span style="color: rgba(0, 0, 0, 1)"> String say(){ </span> <span style="color: rgba(0, 0, 255, 1)">return</span> "springboot-a"+<span style="color: rgba(0, 0, 0, 1)">userService; } @RequestMapping(</span>"/find"<span style="color: rgba(0, 0, 0, 1)">) </span><span style="color: rgba(0, 0, 255, 1)">public</span><span style="color: rgba(0, 0, 0, 1)"> String find(){ User user </span>= userService.find(18<span style="color: rgba(0, 0, 0, 1)">); ModelAndView mav </span>= <span style="color: rgba(0, 0, 255, 1)">new</span><span style="color: rgba(0, 0, 0, 1)"> ModelAndView(); mav.addObject(</span>"user","sadf"<span style="color: rgba(0, 0, 0, 1)">); </span><span style="color: rgba(0, 0, 255, 1)">return</span> "HelloWord"+"fasdf--"+user.getUsername()+"--"+<span style="color: rgba(0, 0, 0, 1)">user.getPassword(); } @RequestMapping(</span>"/ajax"<span style="color: rgba(0, 0, 0, 1)">) </span><span style="color: rgba(0, 0, 255, 1)">public</span><span style="color: rgba(0, 0, 0, 1)"> String find1(){ </span><span style="color: rgba(0, 0, 255, 1)">return</span> "[''message':'123dfx']"<span style="color: rgba(0, 0, 0, 1)">; }// public static void main(String[] args){
// SpringApplication.run(UserController.class,args);
// }
}
（8）ServletInitializer.java 这个类的主要内容如下：
package smm.springboot_ftl;import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.boot.web.support.SpringBootServletInitializer;public class ServletInitializer extends SpringBootServletInitializer {
@Override </span><span style="color: rgba(0, 0, 255, 1)">protected</span><span style="color: rgba(0, 0, 0, 1)"> SpringApplicationBuilder configure(SpringApplicationBuilder application) { </span><span style="color: rgba(0, 0, 255, 1)">return</span> application.sources(Application.<span style="color: rgba(0, 0, 255, 1)">class</span><span style="color: rgba(0, 0, 0, 1)">); }}
（9）SpringBoot 的配置文件： application.properties 文件内容如下：
存储位置： src/main/resources
server.context-path ： 配置访问该项目的项目路径，不配置时默认为 / , 配置后必须加上项目名才能访问项目
server.context-path=/HelloWorld
spring.datasource.driver-class-name =com.mysql.jdbc.Driver
spring.datasource.url =jdbc:mysql://localhost:3306/springboot_mybatis
spring.datasource.username =root
spring.datasource.password =root
mybatis.typeAliasesPackage=smm.springboot_ftl.bean
mybatis.mapperLocations=classpath:/mapper/UserMapper.xml
Freemarker \u914D\u7F6E
\u6587\u4EF6\u914D\u7F6E\u8DEF\u5F84
spring.freemarker.template-loader-path=classpath:/templates/
spring.freemarker.cache=false
spring.freemarker.charset=UTF-8
spring.freemarker.check-template-location=true
spring.freemarker.content-type=text/html
spring.freemarker.expose-request-attributes=true
spring.freemarker.expose-session-attributes=true
spring.freemarker.request-context-attribute=request
spring.freemarker.suffix=.ftl
（10）配置 maven 项目的配置文件，pom.xml
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>smm</groupId> <artifactId>bootdemo</artifactId> <packaging>war</packaging> <version>0.0.1-SNAPSHOT</version> <name>bootdemo Maven Webapp</name> <url>http://maven.apache.org</url><parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>1.5.6.RELEASE</version> <relativePath/> <!-- lookup parent from repository --> </parent> <build> <finalName>bootdemo</finalName> <plugins> <plugin> <inherited><span style="color: rgba(0, 0, 255, 1)">true</span></inherited> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>3.5.1</version> <configuration> <source>${compiler.source}</source> <target>${compiler.target}</target> <encoding>${project.build.sourceEncoding}</encoding> <compilerArguments> <extdirs>${project.basedir}/src/main/webapp/WEB-INF/lib</extdirs> </compilerArguments> </configuration> </plugin> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <compiler.source>1.7</compiler.source> <compiler.target>1.7</compiler.target> <!-- servlet/jsp/EL (2.4/2.0/?)(2.5/2.1/2.1),(3.0/2.2/2.2),(3.1/2.3/3.0) --> <servlet.version>3.1.0</servlet.version> <jsp.version>2.3.1</jsp.version> <jstl.version>1.2</jstl.version> <junit.version>4.12</junit.version> </properties> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>${junit.version}</version> <scope>test</scope> </dependency> <dependency> <groupId>javax.servlet</groupId> <artifactId>javax.servlet-api</artifactId> <version>${servlet.version}</version> <scope>provided</scope> </dependency> <dependency> <groupId>javax.servlet.jsp</groupId> <artifactId>javax.servlet.jsp-api</artifactId> <version>${jsp.version}</version> <scope>provided</scope> </dependency> <dependency> <groupId>javax.servlet</groupId> <artifactId>jstl</artifactId> <version>${jstl.version}</version> </dependency> <dependency> <groupId>org.objenesis</groupId> <artifactId>objenesis</artifactId> <version>1.2</version> </dependency> <dependency> <groupId>org.mybatis.spring.boot</groupId> <artifactId>mybatis-spring-boot-starter</artifactId> <version>1.2.0</version> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-tomcat</artifactId> <scope>provided</scope> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-configuration-processor</artifactId> <optional><span style="color: rgba(0, 0, 255, 1)">true</span></optional> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>5.1.6</version> <scope>runtime</scope> </dependency> <!-- freemarker jar包导入 --> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-freemarker</artifactId> </dependency> </dependencies></project>
（11）启动项目，访问项目。
进入 Application.java
右击 --》 Run As --》 Java Application
启动成功后，在浏览器通过 URL 访问： http:// 当前 ip：8080/server.context-path 指定的值 /RequestMapping 对应的值
例如： http://127.0.0.1:8080/HelloWorld/find
访问结果如图所示：（注意，这里自己要往数据库中插入一条数据，id 为 UserController 类中 find 方法对应的 id）