本文将介绍 spring boot 整合 JPA 来实现数据的持久化。
一、添加依赖
- 修改pom,引入依赖
<!-- 引入jpa 依赖 -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
-
修改
application.properties
,配置相关信息spring.datasource.driver-class-name=com.mysql.jdbc.Driver spring.datasource.url=jdbc:mysql://localhost:3306/test spring.datasource.username=root spring.datasource.password=root spring.jpa.hibernate.ddl-auto=update spring.jpa.show-sql=true spring.jackson.serialization.indent_output=true
-
创建实体类 package com.study.entity;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;
@Entity
@Table(name="t_user")
public class User {
@Id @GeneratedValue(strategy=GenerationType.AUTO)
private Integer id;
private String userName;
private String password;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
}
-
创建repository接口并继承
CrudRepository
package com.study.repository; import org.springframework.data.jpa.repository.Query; import org.springframework.data.repository.CrudRepository; import org.springframework.data.repository.query.Param; import com.study.entity.User; /** - 注意: - 1.这里这里是interface,不是class - - 2.CrudRepository里面的泛型,第一个是实体类,第二个是主键的类型 - - 3.由于crudRepository 里面已经有一些接口了,如deleteAll,findOne等, 我们直接调用即可 - - 4.当然,我们也可以根据自己的情况来实现自己的接口,如下面的getUser()方法,jpql语句和hql语句差不多 - - */ public interface UserRepository extends CrudRepository<User, Integer> { /** - 我们这里只需要写接口,不需要写实现,spring boot会帮忙自动实现 - - */ @Query("from User where id =:id ") public User getUser(@Param("id") Integer id); }
-
创建service 接口
package com.study.service;
import com.study.entity.User;
public interface UserService {
public User getUser(Integer id);
} 实现 package com.study.service.impl;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import com.study.entity.User;
import com.study.repository.UserRepository;
import com.study.service.UserService;
@Service
public class UserServiceImpl implements UserService {
@Autowired
UserRepository repository;
@Override
public User getUser(Integer id) {
//有两种方式:
//1.调用crudRepository的接口
//return repository.findOne(id);
//2.调用我们自己写的接口
return repository.getUser(id);
}
}
- 创建controller
package com.study.controller;
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.study.entity.User;
import com.study.service.UserService;
@RestController
public class UserController {
@Autowired
UserService service;
@RequestMapping("/users/{id}")
public User getUser(@PathVariable("id") Integer id){
return service.getUser(id);
}
}
- 测试,在浏览器中访问
http://localhost:8090/test/users/1