SpringBoot - 使用jpa

1.在springBootStudio项目中添加Module。

2.选择Spring Initializr，点击next。

3.Group填写com.chanchifeng，Artifact填写jpa。

4.勾选SQL中的MySQL和JPA，点击next。

5.Content_root和Module file location选择springBootStudio项目路径。

6.修改pom.xml，核心代码如下：

<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-starter-data-jpa</artifactId>
</dependency>

<!-- MySQL -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>5.1.46</version>
    <scope>runtime</scope>
</dependency>

<!-- druid -->
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid</artifactId>
    <version>1.1.10</version>
</dependency>

7.修改application.properties，代码如下：

###  MySQL 连接信息
spring.datasource.url = jdbc:mysql://127.0.0.1:3306/test?useSSL=true
spring.datasource.username = root
spring.datasource.password = 1qaz2wsx
spring.datasource.driver-class-name = com.mysql.jdbc.Driver

###  数据源类别
spring.datasource.type=com.alibaba.druid.pool.DruidDataSource
### 初始化大小，最小，最大
spring.datasource.initialSize=5
spring.datasource.minIdle=5
spring.datasource.maxActive=20
### 配置获取连接等待超时的时间，单位是毫秒
spring.datasource.maxWait=60000
### 配置间隔多久才进行一次检测，检测需要关闭的空闲连接，单位是毫秒
spring.datasource.timeBetweenEvictionRunsMillis=60000
### 配置一个连接在池中最小生存的时间，单位是毫秒
spring.datasource.minEvictableIdleTimeMillis=300000
spring.datasource.validationQuery=SELECT 1 FROM DUAL
spring.datasource.testWhileIdle=true
spring.datasource.testOnBorrow=false
spring.datasource.testOnReturn=false
### 打开PSCache，并且指定每个连接上PSCache的大小
spring.datasource.poolPreparedStatements=true
spring.datasource.maxPoolPreparedStatementPerConnectionSize=20
### 配置监控统计拦截的filters，去掉后监控界面sql无法统计，'wall'用于防火墙
spring.datasource.filters=stat,wall,log4j
### 通过connectProperties属性来打开mergeSql功能；慢SQL记录
spring.datasource.connectionProperties=druid.stat.mergeSql=true;druid.stat.slowSqlMillis=5000
### 合并多个DruidDataSource的监控数据
#spring.datasource.useGlobalDataSourceStat=true

8.在MySQL中创建一张user表。

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

-- ----------------------------
-- Table structure for user
-- ----------------------------
DROP TABLE IF EXISTS `user`;
CREATE TABLE `user`  (
  `id` int(32) NOT NULL AUTO_INCREMENT COMMENT '主键',
  `name` varchar(10) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '用户名',
  `password` varchar(32) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '密码',
  PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 4 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;

-- ----------------------------
-- Records of user
-- ----------------------------
INSERT INTO `user` VALUES (1, '李四', 'e10adc3949ba59abbe56e057f20f883e');
INSERT INTO `user` VALUES (2, '张三', 'e10adc3949ba59abbe56e057f20f883e');
INSERT INTO `user` VALUES (3, '阿华', 'e10adc3949ba59abbe56e057f20f883e');

SET FOREIGN_KEY_CHECKS = 1;

9.在项目中创建model包，在其下创建User类，代码如下：

@Entity
@Table(name = "user")
public class User {
    @Id
    private String id;
    private String name;
    private String password;

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    @Override
    public String toString() {
        return "AyUser{" +
                "id='" + id + '\'' +
                ", name='" + name + '\'' +
                ", password='" + password + '\'' +
                '}';
    }
}

10.创建repository包，在其下创建UserRepository接口，代码如下：

public interface UserRepository extends JpaRepository<User,String> {
    /**
     * 描述：通过名字相等查询，参数为 name
     * 相当于：select u from ay_user u where u.name = ?1
     */
    List<User> findByName(String name);

    /**
     * 描述：通过名字like查询，参数为 name
     * 相当于：select u from ay_user u where u.name like ?1
     */
    List<User> findByNameLike(String name);

    /**
     * 描述：通过主键id集合查询，参数为 id集合
     * 相当于：select u from ay_user u where id in(?,?,?)
     * @param ids
     */
    List<User> findByIdIn(Collection<String> ids);
}

11.创建service包，在其下创建UserService接口，代码如下：

public interface UserService {
    User findById(String id);
    List<User> findAll();
    User save(User ayUser);
    void delete(String id);

    //分页
    Page<User> findAll(Pageable pageable);

    List<User> findByName(String name);
    List<User> findByNameLike(String name);
    List<User> findByIdIn(Collection<String> ids);
    
}

12.创建service.impl包，在其下创建UserServiceImpl类，代码如下：

@Service
public class UserServiceImpl implements UserService {

    @Resource
    private UserRepository userRepository;

    @Override
    public User findById(String id) {
        return userRepository.findById(id).get();
    }

    @Override
    public List<User> findAll() {
        return userRepository.findAll();
    }

    @Override
    public User save(User ayUser) {
        return userRepository.save(ayUser);
    }

    @Override
    public void delete(String id) {
        userRepository.deleteById(id);
        System.out.println("userId:" + id + "用户被删除");
    }

    @Override
    public Page<User> findAll(Pageable pageable) {
        return userRepository.findAll(pageable);
    }

    @Override
    public List<User> findByName(String name){
        return userRepository.findByName(name);
    }
    @Override
    public List<User> findByNameLike(String name){
        return userRepository.findByNameLike(name);
    }
    @Override
    public List<User> findByIdIn(Collection<String> ids){
        return userRepository.findByIdIn(ids);
    }
}

13.在com.chanchifeng.jpa.JpaApplicationTests编写测试，核心代码如下：

/* 测试jpa */
@Resource
private UserService userService;

@Test
public void testRepository(){
    //查询所有数据
    List<User> userList =  userService.findAll();
    System.out.println("findAll() :" + userList.size());
    //通过name查询数据
    List<User> userList2 = userService.findByName("李四");
    System.out.println("findByName() :" + userList2.size());
    Assert.isTrue(userList2.get(0).getName().equals("李四"),"data error!");
    //通过name模糊查询数据
    List<User> userList3 = userService.findByNameLike("%四%");
    System.out.println("findByNameLike() :" + userList3.size());
    Assert.isTrue(userList3.get(0).getName().equals("李四"),"data error!");
    //通过id列表查询数据
    List<String> ids = new ArrayList<String>();
    ids.add("1");
    ids.add("2");
    List<User> userList4 = userService.findByIdIn(ids);
    System.out.println("findByIdIn() :" + userList4.size());
    //分页查询数据
    PageRequest pageRequest = new PageRequest(0,10);
    Page<User> userList5 =  userService.findAll(pageRequest);
    System.out.println("page findAll():" + userList5.getTotalPages() + "/" + userList5.getSize());
    //新增数据
    User ayUser = new User();
    ayUser.setId("4");
    ayUser.setName("刘六");
    ayUser.setPassword("e10adc3949ba59abbe56e057f20f883e");
    userService.save(ayUser);
    //删除数据
    userService.delete("4");
}

14.测试类的输出结果如下：