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', '張無(wú)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>{
}

//
// 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);

  }

  /**
   * 刪
   * @param id
   */
  @DeleteMapping(value = "delUser/{id}")
  public void delUser(@PathVariable("id") Integer id){
    UserInfo user = new UserInfo();
    user.setId(id);
    userInfoRepository.delete(user);
  }
}