springboot系列07：jpa的使用

Springboot Jpa 介绍

 

Spring Boot Jpa 是 Spring 基于 ORM 框架、Jpa 规范的基础上封装的一套 Jpa 应用框架，可使开发者用极简的代码即可实现对数据的访问和操作。提供了包括增删改查等在内的常用功能，且易于扩展！学习并使用 Spring Data Jpa 可以极大提高开发效率！

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1	Spring Boot Jpa 让我们解脱了 DAO 层的操作，基本上所有 CRUD 都可以依赖于它来实现

 

• 引入相关依赖

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<dependencies>     <dependency>         <groupId>org.springframework.boot</groupId>         <artifactId>spring-boot-starter-data-jpa</artifactId>     </dependency>     <dependency>         <groupId>mysql</groupId>         <artifactId>mysql-connector-java</artifactId>     </dependency>     <dependency>         <groupId>org.springframework.boot</groupId>         <artifactId>spring-boot-starter-test</artifactId>         <scope>test</scope>     </dependency>     <dependency>         <groupId>org.projectlombok</groupId>         <artifactId>lombok</artifactId>         <version>1.16.8</version>     </dependency> </dependencies>

 

• 定义实体Bean

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package com.example.jpa.domain;   import lombok.Data;   import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.Id; import java.io.Serializable;   @Data @Entity(name = "tb_user") public class User implements Serializable {       @Id     @GeneratedValue     private Long id;     @Column(nullable = false, unique = true)     private String userName;     @Column(nullable = false)     private String passWord;     @Column(nullable = false, unique = true)     private String email;     @Column(nullable = true, unique = true)     private String nickName;     @Column(nullable = false)     private String regTime;     @Column(nullable = false)     private Integer age; }

 

• 定义UserRepository接口

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package com.example.jpa.repository;   import com.example.jpa.domain.User; import org.springframework.data.jpa.repository.JpaRepository;   public interface UserRepository extends JpaRepository<User, Long> {   }

 

• 测试保存

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package com.example.jpa.respository;   import com.example.jpa.BaseTest; import com.example.jpa.domain.User; import com.example.jpa.repository.UserRepository; import org.junit.Test;   import javax.annotation.Resource; import java.text.SimpleDateFormat; import java.util.Date;     public class UserRppositoryTest extends BaseTest {       @Resource     private UserRepository userRepository;       @Test     public void testSave(){         User user = new User();         user.setAge(30);         user.setNickName("zhangl1");         user.setUserName("zhangl1");         user.setPassWord("123456");         user.setEmail("17969693891@qq.com");         user.setRegTime(new SimpleDateFormat("yyyy-MM-dd").format(new Date()));        //true         Assert.assertNotNull(userRepository.save(user));     }   }

 

• 测试查询所有

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/**  * 查询所有  */ @Test public void testFindAll(){     Assert.assertEquals(2, userRepository.findAll().size()); }

 

• 测试查询主键

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/**  * 根据主键查询  */ @Test public void testFindById(){     Assert.assertEquals("13128600812",  userRepository.findById(1L).get().getPassWord()); }

 

自定义简单查询

自定义的简单查询就是根据方法名来自动生成 SQL，主要的语法是findXXBy,readAXXBy,queryXXBy,countXXBy, getXXBy后面跟属性名称：

• 接口定义

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public interface UserRepository extends JpaRepository<User, Long> {       User findByUserName(String userName); }

 

• 测试类

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/**   * 根据用户名查询   */  @Test  public void testFindByUserName(){      Assert.assertNotNull( userRepository.findByUserName("zhangl1") );  }