1.先来看一下项目的目录结构

jpa1.jpg

2.在整合之前我们要在pom.xml中添加上依赖

<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.0.28</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.48</version>
        </dependency>

3.加上了必要的依赖后我们就要在application.properties进行丁配置

#配置数据源
spring.datasource.type=com.alibaba.druid.pool.DruidDataSource
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.username=root
spring.datasource.password=tiger
spring.datasource.url=jdbc:mysql://localhost:3306/jpa
#相当于数据库方言
spring.jpa.database=mysql
#是否显示sql语句
spring.jpa.show-sql=true
#格式化sql语句
spring.jpa.properties.hibernate.format_sql=true
spring.jpa.hibernate.ddl-auto=update

4.实体类代码如下

package com.it.entity;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

import javax.persistence.*;

@Data
@Entity
@NoArgsConstructor
@AllArgsConstructor
public class User {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "user_id")
    private int userId;
    @Column(name = "user_name",length = 20,unique = true,nullable = false)
    private String userName;

    @Column(name = "password",length = 20,nullable = false)
    private String password;

    private String addr;
}

5.下面是dao层代码

package com.it.dao;

import com.it.entity.User;
import org.springframework.data.jpa.repository.JpaRepository;

import java.io.Serializable;
import java.util.List;

public interface IUserDao extends JpaRepository<User, Serializable> {
    List<User> findByPassword(String password);
}

6.service层代码

package com.it.service;

import com.it.entity.User;

import java.util.List;

public interface IUserService {
    List<User> getAllUsers();

    void saveUsers(User user);
    List<User> findByPassword(String password);
}

package com.it.service.impl;

import com.it.dao.IUserDao;
import com.it.entity.User;
import com.it.service.IUserService;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;
import java.util.List;

@Service
public class UserServiceImpl implements IUserService {
    @Resource
    private IUserDao userDao;
    @Override
    public List<User> getAllUsers() {
        return userDao.findAll();
    }

    @Override
    public void saveUsers(User user) {
        userDao.saveAndFlush(user);
    }

    @Override
    public List<User> findByPassword(String password) {
        return userDao.findByPassword(password);
    }
}

7.测式代码如下

package com.it.service;

import com.it.entity.User;
import org.junit.jupiter.api.Test;
import org.springframework.boot.test.context.SpringBootTest;

import javax.annotation.Resource;
import java.util.List;

@SpringBootTest
public class TestUserService {
   @Resource
   private IUserService userService;
   @Test
   public void testSaveUser(){
       User user = new User(0,"wen","tiger","安徽安庆");
       userService.saveUsers(user);
   }

   @Test
   public void findUserByPassword(){
       List<User> tiger = userService.findByPassword("tiger");
       System.out.println(tiger);
   }
}

我这里给出了findUserByPassword()测试方法的在控制台打印出来的sql,如果你不在application.properties配置文件中加入spring.jpa.properties.hibernate.format_sql=true就不会像下面一样格式.会显示在一行,这样不方便查看.

Hibernate: 
    select
        user0_.user_id as user_id1_0_,
        user0_.addr as addr2_0_,
        user0_.password as password3_0_,
        user0_.user_name as user_nam4_0_ 
    from
        user user0_ 
    where
        user0_.password=?
[User(userId=2, userName=wen, password=tiger, addr=安徽安庆)]