Spring boot开发web应用JPA过程解析

<!--JPA-->
 <dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-data-jpa</artifactId>
 </dependency>

package com.kinglead.demo.entity;
 ​
 import lombok.AllArgsConstructor;
 import lombok.Data;
 import lombok.NoArgsConstructor;
 ​
 import javax.persistence.*;
 import java.io.Serializable;
 ​
 @Data //添加getter、setter方法
 @NoArgsConstructor  //无参构造函数
 @AllArgsConstructor //所以参数构造函数
 @Entity //声明为JPA实体
 @Table(name = "t_user") //该标注与@Entity标注并列使用，用于指明数据库的表名
 public class User implements Serializable {
   private static final long serialVersionUID = -21070736985722463L;
 ​
   @Id //指明主键
   @GeneratedValue(strategy= GenerationType.AUTO)
   private Long id;
 ​
   @Column(name = "name", columnDefinition = "姓名") //指明字段
   private String name;
 ​
   @Column(name = "password", columnDefinition = "密码") //指明字段
   private String password;
 ​
 }

package com.kinglead.demo.dao;
 ​
 import com.kinglead.demo.entity.User;
 import org.springframework.data.jpa.repository.JpaRepository;
 ​
 public interface UserRepository extends JpaRepository<User, Long>{
 }

package com.kinglead.demo.dao;
 ​
 import com.kinglead.demo.entity.User;
 import org.springframework.data.jpa.repository.JpaRepository;
 ​
 public interface UserRepository extends JpaRepository<User, Long> {
 ​
   User findByNameAndPassword(String name, String password);
 ​
 }

@Query(value = "select id,name,password from t_suer where name=? and password=?", 
    nativeQuery = true)
 User findByNameAndPassword(String name, String password);

package com.kinglead.demo.service.impl;
 ​
 import com.kinglead.demo.dao.UserRepository;
 import com.kinglead.demo.entity.User;
 import com.kinglead.demo.service.UserService;
 import org.springframework.stereotype.Service;
 ​
 import javax.annotation.Resource;
 import java.util.List;
 ​
 @Service
 public class UserServiceImpl implements UserService {
 ​
   @Resource
   private UserRepository userRepository;
 ​
   /**
   * 新增用户
   */
   @Override
   public User insert(User user) {
     return userRepository.save(user);
   }
 ​
   /**
   * 通过用户名和密码查询用户
   */
   @Override
   public User queryByNameAndPassword(User user) {
     return userRepository.findByNameAndPassword(user.getName(), user.getPassword());
   }
 ​
   /**
   * 查询用户列表
   */
   @Override
   public List<User> queryAll() {
     return userRepository.findAll();
   }
 ​
 }