上一篇使用了 JdbcTemplate 去访问数据库，毕竟使用的是原生的 SQL 形式，像我这种懒人是肯定不会考虑的了。。
这次记录下使用 JPA 来极大的减少我们的代码量
首先，还是准备好 SQL 文件
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| DROP TABLE IF EXISTS users;
CREATE TABLE users (
id INT ( 11 ) PRIMARY KEY AUTO_INCREMENT,
username VARCHAR ( 255 ) NOT NULL,
passwd VARCHAR ( 255 )
) ENGINE = INNODB DEFAULT CHARSET = utf8;
INSERT users VALUES ( NULL, '翠花', '123' );
INSERT users VALUES ( NULL, '王卫国', '123' );
INSERT users VALUES ( NULL, '李小花', '123' );
INSERT users VALUES ( NULL, '王二柱', '123' );
INSERT users VALUES ( NULL, '赵铁蛋', '123' );
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这次需要用到的依赖
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| <dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
|
User.java
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| package com.priv.gabriel.entity;
import javax.persistence.*;
@Entity
@Table(name = "users")
public class User {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private long id;
@Column(nullable = false)
private String username;
@Column(nullable = false)
private String passwd;
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPasswd() {
return passwd;
}
public void setPasswd(String passwd) {
this.passwd = passwd;
}
}
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UserController.java
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| package com.priv.gabriel.controller;
import com.priv.gabriel.entity.User;
import com.priv.gabriel.repository.UserRepository;
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.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
import java.util.List;
@RestController
@RequestMapping("/users")
public class UserController {
@Autowired
private UserRepository userRepository;
@RequestMapping(value = "/",method = RequestMethod.GET)
public List<User> usersList(){
return userRepository.findAll();
}
@RequestMapping(value = "/" ,method = RequestMethod.PUT)
public String updateUser(User user){
if(userRepository.save(user) != null){
return "修改成功";
}else{
return "修改失败";
}
}
@RequestMapping(value = "/{id}",method = RequestMethod.GET)
public User selectUserById(@PathVariable long id){
return userRepository.findById(id).get();
}
@RequestMapping(value ="/{id}",method = RequestMethod.DELETE)
public String deleteUser(@PathVariable long id){
userRepository.deleteById(id);
return "删除成功";
}
@RequestMapping(value = "/",method = RequestMethod.POST)
public String saveUser(User user){
System.out.println(userRepository);
if(userRepository.save(user) != null){
return "新增成功";
}else{
return "新增失败";
}
}
}
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此处就偷个懒不写 service 层了，要研究的小朋友还是不要学我哈
UserRepository.java
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| package com.priv.gabriel.repository;
import com.priv.gabriel.entity.User;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;
@Repository
public interface UserRepository extends JpaRepository<User,Long>{
}
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使用 jpa 最大的好处就是你只需要基础一个 JpaRepository 接口，其余的都交给 jpa 自己去处理，我们只负责调用就好了，回到 springboot 的主题就是
just run
###2019/01/27 更新
之前介绍的话可能满足不了日常的使用。
今天更新一下 JPA 的其他用法
#自定义方法
微信
