DROP TABLE IF EXISTS `user_info`;
CREATE TABLE `user_info` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `username` varchar(255) DEFAULT NULL,
  `password` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=3 DEFAULT CHARSET=utf8;
 
-- ----------------------------
-- Records of user_info
-- ----------------------------
INSERT INTO `user_info` VALUES ('1', 'Java之音', '12345');
INSERT INTO `user_info` VALUES ('2', '张无忌', '123');

<dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
 </dependency>
 
 <dependency>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter-data-jpa</artifactId>
 </dependency>

spring:
  datasource:
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://localhost:3306/springboot?useUnicode=true&characterEncoding=UTF-8&useSSL=false
    username: root
    password: 1011
  jpa:
    show-sql: true

package com.javazhiyin;
 
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
 
/**
* Created by 57783 on 2018/7/4.
*/
@Entity
public class UserInfo {
 
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    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;
    }
 
    public UserInfo(){
 
    }
}

package com.javazhiyin;
 
import org.springframework.data.jpa.repository.JpaRepository;
 
/**
* Created by 57783 on 2018/7/4.
*/
public interface UserInfoRepository extends JpaRepository<UserInfo,Integer>{
 
}
 
这里继承了JpaRepository类，其封装了一些对数据库操作的基本方法，我们通过源码查看一下JpaRepository有哪些方法：
//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by Fernflower decompiler)
//
 
package org.springframework.data.repository;
 
import java.util.Optional;
 
@NoRepositoryBean
public interface CrudRepository<T, ID> extends Repository<T, ID> {
    <S extends T> S save(S var1);
 
    <S extends T> Iterable<S> saveAll(Iterable<S> var1);
 
    Optional<T> findById(ID var1);
 
    boolean existsById(ID var1);
 
    Iterable<T> findAll();
 
    Iterable<T> findAllById(Iterable<ID> var1);
 
    long count();
 
    void deleteById(ID var1);
 
    void delete(T var1);
 
    void deleteAll(Iterable<? extends T> var1);
 
    void deleteAll();
}

package com.javazhiyin;
 
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
 
import java.util.List;
 
/**
* Created by 57783 on 2018/7/4.
*/
@RestController
public class UserInfoController {
 
    @Autowired
    private UserInfoRepository userInfoRepository;
 
    /**
     * 查
     * @return
     */
    @GetMapping(value = "/list")
    public List<UserInfo> getUserList(){
        return userInfoRepository.findAll();
    }
 
    /**
     * 增
     * @param username
     * @param password
     * @return
     */
    @PostMapping(value = "/addUser")
    public UserInfo addUser(@RequestParam("username") String username,
                            @RequestParam("password") String password){
        UserInfo user = new UserInfo();
        user.setUsername(username);
        user.setPassword(password);
        return userInfoRepository.save(user);
    }
 
    /**
     * 改
     * @param id
     * @param username
     * @param password
     * @return
     */
    @PutMapping(value = "updUser/{id}")
    public UserInfo updUser(@PathVariable("id") Integer id,
                        @RequestParam("username") String username,
                        @RequestParam("password") String password){
        UserInfo user = new UserInfo();
        user.setId(id);
        user.setUsername(username);
        user.setPassword(password);
        return userInfoRepository.save(user);
 
    }
 
    /**
     * 删
     * @param id
     */
    @DeleteMapping(value = "delUser/{id}")
    public void delUser(@PathVariable("id") Integer id){
        UserInfo user = new UserInfo();
        user.setId(id);
        userInfoRepository.delete(user);
    }
 
}