"[链接] 阅读目录[链接] [链接] [链接] [链接] [链接] [链接] [链接] [链接] [链接][链接]关于 Spring Data[链接] Spring 社区的一个顶级工程，主要用于简化数据（关系型 & 非关系型）访问，如果我们使用 Spring Data 来开发程序的话，那么可 ...."

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Spring Data JPA例子[基于Spring Boot、Mysql]

阅读目录#

关于 Spring Data#

Spring 社区的一个顶级工程，主要用于简化数据（关系型 & 非关系型）访问，如果我们使用 Spring Data 来开发程序的话，那么可以省去很多低级别的数据访问操作，如编写数据查询语句、DAO 类等，我们仅需要编写一些抽象接口并定义相关操作即可，Spring 会在运行期间的时候创建代理实例来实现我们接口中定义的操作。

关于 Spring Data 子项目#

Spring Data 拥有很多子项目，除了 Spring Data Jpa 外，还有如下子项目。

Spring Data Commons

Spring Data MongoDB

Spring Data Redis

Spring Data Solr

Spring Data Gemfire

Spring Data REST

Spring Data Neo4j

关于 Spring Data Jpa#

Spring Data Jpa 是 Spring Data 的一个子项目，主要用于简化数据访问层的实现，使用 Spring Data Jpa 可以轻松实现增删改查、分页、排序等。

例子，Spring Boot + Spring Data Jpa#

1、添加 POM.XML 文件#

如下所示:

<?xml version="1.0" encoding="UTF-8"?>
<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/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">groupId</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>com.example<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">groupId</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)">artifactId</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>demo<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">artifactId</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)">version</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>0.0.1-SNAPSHOT<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">version</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)">packaging</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>jar<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">packaging</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)">name</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>spring-data-jpa-example<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">name</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)">description</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>Demo project for Spring Boot<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">description</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)">parent</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)">groupId</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>org.springframework.boot<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">groupId</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)">artifactId</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>spring-boot-starter-parent<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">artifactId</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)">version</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>1.4.4.RELEASE<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">version</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)">relativePath </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)"> lookup parent from repository </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)">parent</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)">properties</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)">project.build.sourceEncoding</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>UTF-8<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">project.build.sourceEncoding</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)">project.reporting.outputEncoding</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>UTF-8<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">project.reporting.outputEncoding</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)">java.version</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>1.7<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">java.version</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)">properties</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)">dependencies</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)">dependency</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)">groupId</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>org.springframework.boot<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">groupId</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)">artifactId</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>spring-boot-starter-data-jpa<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">artifactId</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)">dependency</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)">dependency</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)">groupId</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>org.springframework.boot<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">groupId</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)">artifactId</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>spring-boot-starter-web<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">artifactId</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)">dependency</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)">dependency</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)">groupId</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>org.springframework.boot<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">groupId</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)">artifactId</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>spring-boot-starter-test<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">artifactId</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)">scope</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>test<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">scope</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)">dependency</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)">dependency</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)">groupId</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>mysql<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">groupId</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)">artifactId</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>mysql-connector-java<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">artifactId</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)">dependency</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)">dependency</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)">groupId</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>org.springframework.boot<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">groupId</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)">artifactId</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>spring-boot-starter-cache<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">artifactId</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)">dependency</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)">dependencies</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)">build</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)">plugins</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)">plugin</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)">groupId</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>org.springframework.boot<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">groupId</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)">artifactId</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>spring-boot-maven-plugin<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">artifactId</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)">plugin</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)">plugins</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)">build</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>

</project>

其中，spring-boot-starter-parent 会加载 Spring Boot 应用所需的所有默认配置；

spring-boot-starter-data-jpa 会下载所有 Spring Data Jpa 所需的依赖；

添加 spring-boot-starter-web 是因为我们的工程是一个 Web 应用；

另外我们的数据库是 mysql，所以还需要 mysql-connector-java 依赖；

由于使用了缓存，所以再添加一个 spring-boot-starter-cache 依赖；

2、编写实体类 User#

package com.example.domain;
import java.io.Serializable;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.NamedQuery;
@Entity
@NamedQuery(name = "User.findByName", query = "select name,address from User u where u.name=?1")
public class User implements Serializable
{
private static final long serialVersionUID = 1L;
@Id
long id;
@Column(name = "name")
String name;
@Column(name = "address")
String address;
</span><span style="color: rgba(0, 0, 255, 1)">public</span> <span style="color: rgba(0, 0, 255, 1)">long</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)">long</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 getName()
{
    </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> name;
}

</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)"> setName(String name)
{
    </span><span style="color: rgba(0, 0, 255, 1)">this</span>.name =<span style="color: rgba(0, 0, 0, 1)"> name;
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span><span style="color: rgba(0, 0, 0, 1)"> String getAddress()
{
    </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> address;
}

</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)"> setAddress(String address)
{
    </span><span style="color: rgba(0, 0, 255, 1)">this</span>.address =<span style="color: rgba(0, 0, 0, 1)"> address;
}

}

其它没啥好说的，注意下这里的 @NamedQuery 注解，大致意思就是让我们在 Repository 接口中定义的 findByName 方法不使用默认的查询实现，取而代之的是使用这条自定义的查询语句去查询，如果这里没有标注的话，会使用默认实现的。

3、编写 Repository 接口#

这里将编写两个 Repository 接口，仅仅用于示例，实际中可以合并成一个：

UserJpaRepository

package com.example.repository;
import org.springframework.data.jpa.repository.JpaRepository;
import com.example.domain.User;
public interface UserJpaRepository extends JpaRepository<User,Long> {
}

这里的 UserJpaRepository 接口实现了 JpaRepository 接口；

实际上 JpaRepository 实现了 PagingAndSortingRepository 接口，PagingAndSortingRepository 接口实现了 CrudRepository 接口，CrudRepository 接口实现了 Repository 接口；

简单说明下：

Repository 接口是一个标识接口，里面是空的；

CrudRepository 接口定义了增删改查方法；

PagingAndSortingRepository 接口用于分页和排序；

由于 JpaRepository 接口继承了以上所有接口，所以拥有它们声明的所有方法；

另外注意下，以 findAll 方法为例，JpaRepository 接口返回的是 List, PagingAndSortingRepository 和 CrudRepository 返回的是迭代器；

UserRepository

package com.example.repository;
import java.util.List;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.Repository;
import org.springframework.data.repository.query.Param;
import com.example.domain.User;
public interface UserRepository extends Repository<User, Long>
{
List</span>&lt;User&gt;<span style="color: rgba(0, 0, 0, 1)"> findByNameAndAddress(String name, String address);

@Query(value </span>= "from User u where u.name=:name"<span style="color: rgba(0, 0, 0, 1)">)
List</span>&lt;User&gt; findByName1(@Param("name"<span style="color: rgba(0, 0, 0, 1)">) String name);

@Query(value </span>= "select * from #{#entityName} u where u.name=?1", nativeQuery = <span style="color: rgba(0, 0, 255, 1)">true</span><span style="color: rgba(0, 0, 0, 1)">)
List</span>&lt;User&gt;<span style="color: rgba(0, 0, 0, 1)"> findByName2(String name);

List</span>&lt;User&gt;<span style="color: rgba(0, 0, 0, 1)"> findByName(String name);

}

这里的 UserRepository 接口主要定义了一些查询方法；

比如这里的findByNameAndAddress和findByName方法，我们是不需要额外定义其它查询语句就可以直接执行的，Spring Data Jpa 会根据实体类的属性名字以及方法名自动实现该方法；PS: 由于我们在实体类中声明了 @NamedQuery 注解，实际上findByName方法会使用 @NamedQuery 注解标注的查询语句去查询；

另外这里的 findByName1 方法使用了 HQL 语句查询；

findByName2 方法使用了原始的 sql 语句查询；

4、编写 Service#

service 接口：

package com.example.service;
import java.util.List;
import com.example.domain.User;
public interface IUserService
{
public List<User> findAll();
</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)"> saveUser(User book);

</span><span style="color: rgba(0, 0, 255, 1)">public</span> User findOne(<span style="color: rgba(0, 0, 255, 1)">long</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> delete(<span style="color: rgba(0, 0, 255, 1)">long</span><span style="color: rgba(0, 0, 0, 1)"> id);

</span><span style="color: rgba(0, 0, 255, 1)">public</span> List&lt;User&gt;<span style="color: rgba(0, 0, 0, 1)"> findByName(String name);

}

接口实现类：

package com.example.service.impl;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import com.example.domain.User;
import com.example.repository.UserRepository;
import com.example.repository.UserJpaRepository;
import com.example.service.IUserService;
@Service
@Transactional
public class UserServiceImpl implements IUserService
{
@Autowired
private UserJpaRepository userJpaRepository;
@Autowired
private UserRepository userRepository;
</span><span style="color: rgba(0, 0, 255, 1)">public</span> List&lt;User&gt;<span style="color: rgba(0, 0, 0, 1)"> findAll()
{
    </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> userJpaRepository.findAll();
}

</span><span style="color: rgba(0, 0, 255, 1)">public</span> List&lt;User&gt;<span style="color: rgba(0, 0, 0, 1)"> findByName(String name)
{
    List</span>&lt;User&gt; userList1 =<span style="color: rgba(0, 0, 0, 1)"> userRepository.findByName1(name);
    List</span>&lt;User&gt; userList2 =<span style="color: rgba(0, 0, 0, 1)"> userRepository.findByName2(name);
    List</span>&lt;User&gt; userList3 = userRepository.findByNameAndAddress(name, "3"<span style="color: rgba(0, 0, 0, 1)">);
    System.out.println(</span>"userList1:" +<span style="color: rgba(0, 0, 0, 1)"> userList1);
    System.out.println(</span>"userList2:" +<span style="color: rgba(0, 0, 0, 1)"> userList2);
    System.out.println(</span>"userList3:" +<span style="color: rgba(0, 0, 0, 1)"> userList3);
    </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> userRepository.findByName(name);
}

</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)"> saveUser(User book)
{
    userJpaRepository.save(book);
}

@Cacheable(</span>"users"<span style="color: rgba(0, 0, 0, 1)">)
</span><span style="color: rgba(0, 0, 255, 1)">public</span> User findOne(<span style="color: rgba(0, 0, 255, 1)">long</span><span style="color: rgba(0, 0, 0, 1)"> id)
{
    System.out.println(</span>"Cached Pages"<span style="color: rgba(0, 0, 0, 1)">);
    </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> userJpaRepository.findOne(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)">long</span><span style="color: rgba(0, 0, 0, 1)"> id)
{
    userJpaRepository.delete(id);
}

}

这个没啥好说的，调用 Repository 接口接口的方法即可。

5、编写 Controller#

Controller 也没啥好说的，调用 Service 即可，注意下这里的 Controller 使用 @RestController 注解来标注，另外 URL 路径命名按照 RESTful 风格来命名；

package com.example.web;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import com.example.domain.User;
import com.example.service.IUserService;
@RestController
@RequestMapping(value = "/users")
public class UserController
{
@Autowired
private IUserService userService;
@RequestMapping(value </span>= "/add/{id}/{name}/{address}"<span style="color: rgba(0, 0, 0, 1)">)
</span><span style="color: rgba(0, 0, 255, 1)">public</span> User addUser(@PathVariable <span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> id, @PathVariable String name,
    @PathVariable String address)
{
    User user </span>= <span style="color: rgba(0, 0, 255, 1)">new</span><span style="color: rgba(0, 0, 0, 1)"> User();
    user.setId(id);
    user.setName(name);
    user.setAddress(address);
    userService.saveUser(user);
    </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> user;
}

@RequestMapping(value </span>= "/delete/{id}"<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, 255, 1)">void</span> deleteBook(@PathVariable <span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> id)
{
    userService.delete(id);
}

@RequestMapping(value </span>= "/"<span style="color: rgba(0, 0, 0, 1)">)
</span><span style="color: rgba(0, 0, 255, 1)">public</span> List&lt;User&gt;<span style="color: rgba(0, 0, 0, 1)"> getBooks()
{
    </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> userService.findAll();
}

@RequestMapping(value </span>= "/{id}"<span style="color: rgba(0, 0, 0, 1)">)
</span><span style="color: rgba(0, 0, 255, 1)">public</span> User getUser(@PathVariable <span style="color: rgba(0, 0, 255, 1)">int</span><span style="color: rgba(0, 0, 0, 1)"> id)
{
    User user </span>=<span style="color: rgba(0, 0, 0, 1)"> userService.findOne(id);
    </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> user;
}

@RequestMapping(value </span>= "/search/name/{name}"<span style="color: rgba(0, 0, 0, 1)">)
</span><span style="color: rgba(0, 0, 255, 1)">public</span> List&lt;User&gt;<span style="color: rgba(0, 0, 0, 1)"> getBookByName(@PathVariable String name)
{
    List</span>&lt;User&gt; users =<span style="color: rgba(0, 0, 0, 1)"> userService.findByName(name);
    </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> users;
}

}

6、配置 datasource#

在 application.properties 文件中添加如下配置：

spring.jpa.show-sql = true
logging.level.org.springframework.data=DEBUG
spring.jpa.hibernate.ddl-auto=
spring.datasource.url=jdbc:mysql://localhost:3306/demo
spring.datasource.username=root
spring.datasource.password=root
spring.datasource.driver-class-name=com.mysql.jdbc.Driver

如果你使用 STS IDE 的话，这些属性配置都会自动提示的，省的去查找。

想查看 spring.datasource 的配置，可以参考这个类:DataSourceProperties.java

7、编写启动类#

比较简单，注意下该类所属的包级别要大于或等于其它类，以保证其它类的注解可以被扫描到。

package com.example;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cache.annotation.EnableCaching;
@SpringBootApplication
@EnableCaching
public class SpringDataJpaExampleApplication {
</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, 255, 1)">void</span><span style="color: rgba(0, 0, 0, 1)"> main(String[] args) {
    SpringApplication.run(SpringDataJpaExampleApplication.</span><span style="color: rgba(0, 0, 255, 1)">class</span><span style="color: rgba(0, 0, 0, 1)">, args);
}

}

运行、测试程序#

启动 main 方法，或打成 jar 包运行；

浏览器输入以下 URL，测试即可：

http://localhost:8080/users/

http://localhost:8080/users/add/100/110/111

http://localhost:8080/users/delete/100

http://localhost:8080/users/2

http://localhost:8080/users/search/name/2

程序源码#

https://github.com/peterchenhdu/spring-data-jpa-example

参考资料#

http://docs.spring.io/spring-data/jpa/docs/1.11.0.RELEASE/reference/html/

http://javabeat.net/spring-data-jpa/

https://spring.io/guides/gs/caching/

Spring Data JPA例子[基于Spring Boot、Mysql]

阅读目录#

关于 Spring Data#

关于 Spring Data 子项目#

关于 Spring Data Jpa#

例子，Spring Boot + Spring Data Jpa#

1、添加 POM.XML 文件#

2、编写实体类 User#

3、编写 Repository 接口#

4、编写 Service#

5、编写 Controller#

6、配置 datasource#

7、编写启动类#

运行、测试程序#

程序源码#

参考资料#

相关帖子

随便看看

Spring Data JPA例子[基于Spring Boot、Mysql]