spring boot jpadata 使用

 JPA（Java Persistence API）是一种Java持久化解决方案，负责把数据保存到数据库，实际上它就是一种标准、规范，而不是具体的实现。JPA属于重量级的，因为它需要运行在JAVA EE容器中，而Spring Data JPA提供了轻量级的实现，在任何servlet容器中都可以运行。
        Spring Data JPA相对于JAVA EE中的JPA，配置更简单，以轻量级的方式实现了部分在 EJB 容器环境下才具有的功能，将 EntityManager 的创建与销毁、事务管理等代码抽取出来，并由其统一管理，并且极大的简化了数据库访问层的代码。

//pom配置

　　　　<!--引入MySQL的依赖关系-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
//application.properties 配置

spring.freemarker.cache=false 
spring.datasource.url=jdbc:mysql://localhost:3306/test?useUnicode=true&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=UTC 
spring.datasource.username=root
spring.datasource.password=root
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

spring.jpa.database=mysql
#是否显示sql语句
spring.jpa.show-sql=true
#自动建表
spring.jpa.hibernate.ddl-auto=update

实现接口用于对实体操作

package com.zjx.springbootjpadata.jpainterface;

import com.zjx.springbootjpadata.pojo.User;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;

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

/**
 * JpaRepository 简单查询接口
 * JpaSpecificationExecutor  复杂查询接口
 * Serializable 序列化接口
 */
public interface UserJpa extends JpaRepository<User,Long>, JpaSpecificationExecutor<User>, Serializable {

    List<User> findAllByUserName(String username);
}
测试用例 

package com.zjx.springbootjpadata;

import com.zjx.springbootjpadata.jpainterface.UserJpa;
import com.zjx.springbootjpadata.pojo.User;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

/**
 * 使用SpringDataJPA完成数据的CRUD
 */
@RunWith(SpringRunner.class)
@SpringBootTest
public class SpringbootjpadataApplicationTests {

    @Autowired
    private UserJpa userjpa;

    //新增
    @Test
    public void save(){

        User user = new User("张一","16","地球村");
        userjpa.save(user);
    }

    //批量新增
    @Test
    public void saveAll(){

        ArrayList<User> userList = new ArrayList<User>();
        User user1 = new User("张一","10","地球村1号");
        User user2 = new User("张二","11","地球村2号");
        User user3 = new User("张三","12","地球村3号");
        User user4 = new User("张四","13","地球村4号");
        User user5 = new User("张五","14","地球村5号");
        User user6 = new User("张六","15","地球村6号");
        userList.add(user1);
        userList.add(user2);
        userList.add(user3);
        userList.add(user4);
        userList.add(user5);
        userList.add(user6);

        userjpa.saveAll(userList);
    }

    //查询所有
    @Test
    public void findAll(){

        List<User> list = userjpa.findAll();
        for(User u:list){

            System.out.println(u.toString());

        }
        System.out.println(list.size());

    }
    //查询
    @Test
    public void findByName(){

        List<User> list = userjpa.findAllByUserName("张一");
        for(User u:list){

            System.out.println(u.toString());

        }
        System.out.println(list.size());

    }

    //更新
    @Test
    public void updateName(){


        List<User> list = userjpa.findAllByUserName("张一");
        for(User u:list){

            u.setUserName("张");
            userjpa.save(u);
            System.out.println(u.toString());

        }
        System.out.println(list.size());

    }

    //删除
    @Test
    public void deleName(){


        List<User> list = userjpa.findAllByUserName("张");
        for(User u:list){


            userjpa.delete(u);
            System.out.println(u.toString());

        }
        System.out.println(list.size());

    }
}

以上是自学总结。有借鉴前辈帖子望见谅。不足之处请多多指教