JPA学习笔记

Posted 2023-01-11 普通网友

JPA整合Spring

applicationContext.xml

<?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:tx="http://www.springframework.org/schema/tx"
	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-4.0.xsd
		http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd">

	<!-- 配置自动扫描的包 -->
	<context:component-scan base-package="com.atguigu.jpa"></context:component-scan>

	<!-- 配置 C3P0 数据源 -->
	<context:property-placeholder location="classpath:db.properties"/>

	<bean id="dataSource"
		class="com.mchange.v2.c3p0.ComboPooledDataSource">
		<property name="user" value="$jdbc.user"></property>
		<property name="password" value="$jdbc.password"></property>
		<property name="driverClass" value="$jdbc.driverClass"></property>
		<property name="jdbcUrl" value="$jdbc.jdbcUrl"></property>	
		
		<!-- 配置其他属性 -->
	</bean>
	
	<!-- 配置 EntityManagerFactory -->
	<bean id="entityManagerFactory"
		class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
		<property name="dataSource" ref="dataSource"></property>
		<!-- 配置 JPA 提供商的适配器. 可以通过内部 bean 的方式来配置 -->
		<property name="jpaVendorAdapter">
			<bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter"></bean>
		</property>	
		<!-- 配置实体类所在的包 -->
		<property name="packagesToScan" value="com.atguigu.jpa.spring.entities"></property>
		<!-- 配置 JPA 的基本属性. 例如 JPA 实现产品的属性 -->
		<property name="jpaProperties">
			<props>
				<prop key="hibernate.show_sql">true</prop>
				<prop key="hibernate.format_sql">true</prop>
				<prop key="hibernate.hbm2ddl.auto">update</prop>
			</props>
		</property>
	</bean>
	
	<!-- 配置 JPA 使用的事务管理器 -->
	<bean id="transactionManager"
		class="org.springframework.orm.jpa.JpaTransactionManager">
		<property name="entityManagerFactory" ref="entityManagerFactory"></property>	
	</bean>
	
	<!-- 配置支持基于注解是事务配置 -->
	<tx:annotation-driven transaction-manager="transactionManager"/>

</beans>

Person.java

package com.atguigu.jpa.spring.entities;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;

@Table(name="JPA_PERSONS")
@Entity
public class Person 

	private Integer id;
	private String lastName;

	private String email;
	private int age;

	@GeneratedValue
	@Id
	public Integer getId() 
		return id;
	

	public void setId(Integer id) 
		this.id = id;
	

	@Column(name="LAST_NAME")
	public String getLastName() 
		return lastName;
	

	public void setLastName(String lastName) 
		this.lastName = lastName;
	

	public String getEmail() 
		return email;
	

	public void setEmail(String email) 
		this.email = email;
	

	public int getAge() 
		return age;
	

	public void setAge(int age) 
		this.age = age;
	

PersonDao.java

package com.atguigu.jpa.dao;

import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;

import org.springframework.stereotype.Repository;

import com.atguigu.jpa.spring.entities.Person;

@Repository
public class PersonDao 

	//如何获取到和当前事务关联的 EntityManager 对象呢 ?
	//通过 @PersistenceContext 注解来标记成员变量!
	@PersistenceContext
	private EntityManager entityManager;
	
	public void save(Person person)
		entityManager.persist(person);
	
	

PersonService.java

package com.atguigu.jpa.service;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import com.atguigu.jpa.dao.PersonDao;
import com.atguigu.jpa.spring.entities.Person;

@Service
public class PersonService 
	
	@Autowired
	private PersonDao personDao;
	
	@Transactional
	public void savePersons(Person p1, Person p2)
		personDao.save(p1);
		
		int i = 10 / 0;
		
		personDao.save(p2);
	
	

JPATest.java

package com.atguigu.jpa.spring;

import java.sql.SQLException;

import javax.sql.DataSource;

import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.atguigu.jpa.service.PersonService;
import com.atguigu.jpa.spring.entities.Person;

public class JPATest 
	
	private ApplicationContext ctx = null;
	private PersonService personService = null;
	
	
		ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
		personService = ctx.getBean(PersonService.class);
	
	
	@Test
	public void testPersonService()
		Person p1 = new Person();
		p1.setAge(11);
		p1.setEmail("[e-mail]");
		p1.setLastName("AA");
		
		Person p2 = new Person();
		p2.setAge(12);
		p2.setEmail("[e-mail]");
		p2.setLastName("BB");
		
		System.out.println(personService.getClass().getName());
		personService.savePersons(p1, p2);
	
	
	@Test
	public void testDataSource() throws SQLException 
		DataSource dataSource = ctx.getBean(DataSource.class);
		System.out.println(dataSource.getConnection());