SpringDataJPA之快速入门

怼烎@ 2022-01-30 06:53 300阅读 0赞

Spring Data JPA：Spring Data JPA 是 spring data 项目下的一个模块。提供了一套基于 JPA标准操作数据库的简化方案。底层默认的是依赖 Hibernate JPA 来实现的。  
  Spring Data JPA 的技术特点：我们只需要定义接口并集成 Spring Data JPA 中所提供的接口就可以了。不需要编写接口实现类。

# SpringDataJPA #

## 一、接口继承结构 ##

在搭建入门案例之前我们先来看下SpringDataJPA中所需要使用到的几个接口的继承结构图，便于我们后面的分析。

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## 二、入门案例 ##

我们先通过JpaRepoistry接口来快速实现一个添加操作

### 1.创建maven项目 ###

创建一个简单的maven项目即可

### 2.添加相关依赖 ###

基础依赖和前面介绍的hibernateJPA是一样的，额外再添加SpringDataJPA的依赖即可，具体如下:

<dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>4.3.21.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <version>1.6.8.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>com.mchange</groupId>
            <artifactId>c3p0</artifactId>
            <version>0.9.5.3</version>
        </dependency>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-core</artifactId>
            <version>5.0.7.Final</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-orm</artifactId>
            <version>4.3.21.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.32</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
            <version>4.3.21.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-entitymanager</artifactId>
            <version>5.0.7.Final</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.data</groupId>
            <artifactId>spring-data-jpa</artifactId>
            <version>1.9.0.RELEASE</version>
        </dependency>
    </dependencies>

### 3.添加配置文件 ###

一个数据库的配置文件及spring的配置文件，注意添加jps的schema。如下:

jdbc.url=jdbc:mysql://localhost:3306/ssm?characterEncoding=utf-8
    jdbc.driver.class=com.mysql.jdbc.Driver
    jdbc.username=root
    jdbc.password=123456

<?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx" xmlns:jpa="http://www.springframework.org/schema/data/jpa" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd http://www.springframework.org/schema/data/jpa http://www.springframework.org/schema/data/jpa/spring-jpa.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd">
    	
    	
    	<context:property-placeholder location="classpath:jdbc.properties"/>
    	
    	
    	<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
    		<property name="jdbcUrl" value="${jdbc.url}"/>
    		<property name="driverClass" value="${jdbc.driver.class}"/>
    		<property name="user" value="${jdbc.username}"/>
    		<property name="password" value="${jdbc.password}"/>
    	</bean>
    
    	
    	<bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
    		<property name="dataSource" ref="dataSource"/>
    		<property name="jpaVendorAdapter">
    			<bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
    				
    				
    				<property name="database" value="MYSQL"/>
    				
    				<property name="generateDdl" value="true"/>
    				
    				<property name="showSql" value="true"/>
    			</bean>
    		</property>
    		
    		<property name="packagesToScan">
    			<list>
    				<value>com.dpb.pojo</value>
    			</list>
    		</property>
    	</bean>
    	
    	<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
    		<property name="entityManagerFactory" ref="entityManagerFactory"/>
    	</bean>
    	
    	
    	<tx:annotation-driven transaction-manager="transactionManager"/>
    	
    	
    	<context:component-scan base-package="com.dpb"/>
    
    	
    	
    	<jpa:repositories base-package="com.dpb.dao"/>
    </beans>

### 4.创建pojo和Dao接口 ###

创建pojo类Users和Dao接口如下:

package com.dpb.pojo;
    
    import javax.persistence.*;
    import java.io.Serializable;
    
    /** * @program: spring-hibernate-jpa * @description: Users的Pojo对象 * @author: 波波烤鸭 * @create: 2019-05-18 09:37 */
    
    @Entity
    @Table(name="users")
    public class Users implements Serializable { 
    
        @Id
        @GeneratedValue(strategy= GenerationType.IDENTITY)//strategy=GenerationType.IDENTITY 自增长
        @Column(name="userid")
        private Integer userid;
    
        @Column(name="username")
        private String username;
    
        @Column(name="userage")
        private Integer userage;
    
        public Integer getUserid() { 
            return userid;
        }
    
        public void setUserid(Integer userid) { 
            this.userid = userid;
        }
    
        public String getUsername() { 
            return username;
        }
    
        public void setUsername(String username) { 
            this.username = username;
        }
    
        public Integer getUserage() { 
            return userage;
        }
    
        public void setUserage(Integer userage) { 
            this.userage = userage;
        }
    
        @Override
        public String toString() { 
            return "Users [userid=" + userid + ", username=" + username + ", userage=" + userage + "]";
        }
    
    }

/** * SpringDataJPA 实现JpaRepository * 泛型 第一个参数是对应的Pojo类型 * 第二个参数是注解的包装类型 */
    public interface UserDao extends JpaRepository<Users,Integer> { 
    
    }

### 5.单元测试 ###

/** * @program: spring-data-jpa * @description: 单元测试 * @author: 波波烤鸭 * @create: 2019-05-18 09:48 */
    @RunWith(SpringJUnit4ClassRunner.class)
    @ContextConfiguration("classpath:applicationContext.xml")
    public class TestDemo { 
    
        @Autowired
        private UserDao usersDao;
    
    
        /** * 添加用户 */
        @Test
        @Transactional// 在测试类对于事务提交方式默认的是回滚。
        @Rollback(false)//取消自动回滚
        public void testInsertUsers(){ 
            Users users = new Users();
            users.setUserage(20);
            users.setUsername("张三-jpa");
            this.usersDao.save(users);
        }
    }

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