Spring对JPA提供的支持

小咪咪 2022-07-21 00:18 184阅读 0赞

JPA 本身可以工作，但是Spring呢 也对其提供了支持。

相对于JPA自己工作，Spring支持后代码量得到了简化，使得开发人员专注于关系自己的业务逻辑

首先将applicationContext.xml这个Spring的配置文件给贴上来，

内容是

<?xml version="1.0" encoding="UTF-8"?>  
  
<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  
xmlns:p="http://www.springframework.org/schema/p" xmlns:context="http://www.springframework.org/schema/context"  
xmlns:tx="http://www.springframework.org/schema/tx" xmlns:jpa="http://www.springframework.org/schema/data/jpa"  
xmlns="http://www.springframework.org/schema/beans"  
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.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  
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">  
  
  
<context:component-scan base-package="org.test" />  
  
  
<tx:annotation-driven transaction-manager="transactionManager" />  
  
  
  
  
<bean id="entityManagerFactory"  
class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">  
</bean>  
  
  
<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">  
<property name="entityManagerFactory" ref="entityManagerFactory" />  
</bean>  
  
  
</beans>

在看我们的Student.java这个POJO

\-------------------------------------------------------------------------------------------------------------------------------

package org.test.domain;  
  
  
import javax.persistence.Entity;  
import javax.persistence.GeneratedValue;  
import javax.persistence.GenerationType;  
import javax.persistence.Id;  
import javax.persistence.Table;  
  
  
@Entity  
@Table(name="student")  
public class Student  
\{  
private int id ;  
  
private String name ;  
  
public Student()  
\{  
  
\}  
  
public Student(String name )  
\{  
this.name = name ;  
\}  
  
  
@Id  
@GeneratedValue(strategy=GenerationType.AUTO)  
public int getId()  
\{  
return id;  
\}  
  
  
public void setId(int id)  
\{  
this.id = id;  
\}  
  
  
public String getName()  
\{  
return name;  
\}  
  
  
public void setName(String name)  
\{  
this.name = name;  
\}  
  
\}

对于JPA的核心配置文件persistence.xml 还是不能省略的

内容如下

\------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

<?xml version="1.0" encoding="UTF-8"?>  
<persistence xmlns="http://java.sun.com/xml/ns/persistence" version="2.0">  
<persistence-unit name="JPATest" transaction-type="RESOURCE\_LOCAL">  
<provider>org.hibernate.ejb.HibernatePersistence</provider>  
  
  
        <class>org.test.domain.Student</class>  
<properties>  
<property name="hibernate.connection.driver\_class" value="com.mysql.jdbc.Driver"/>  
<property name="hibernate.connection.url" value="jdbc:mysql://localhost:3306/test"/>  
<property name="hibernate.connection.username" value="root"/>  
<property name="hibernate.connection.password" value=""/>  
<property name="hibernate.dialect" value="org.hibernate.dialect.MySQL5Dialect"/>  
<property name="hibernate.show\_sql" value="true"/>  
<property name="hibernate.format\_sql" value="true"/>  
<property name="hibernate.use\_sql\_comments" value="false"/>  
<property name="hibernate.hbm2ddl.auto" value="update"/>  
</properties>  
</persistence-unit>  
</persistence>

\-----------------------------------------------------------------------------------------------------------------------------------------------------------

先看Dao层的StudentDao.java

package org.test.dao;  
  
  
import org.test.domain.Student;  
  
  
public interface StudentDao  
\{  
void store(Student student);  
\}

\-----------------------------------------------------------------------------------------------------------------------------------------------------------

再看StudentDao的实现类 StudentDaoImpl.java

package org.test.dao;  
  
  
import javax.persistence.EntityManager;  
import javax.persistence.PersistenceContext;  
import javax.transaction.Transactional;  
  
  
import org.springframework.stereotype.Repository;  
import org.test.domain.Student;  
  
  
@Repository("studentDao")  
public class StudentDaoImpl implements StudentDao  
\{  
  
  
@PersistenceContext  
private EntityManager em ;  
  
public EntityManager getEm()  
\{  
return em;  
\}  
public void setEm(EntityManager em)  
\{  
this.em = em;  
\}  
@Override  
  
@Transactional  
public void store(Student student)  
\{  
em.persist(student);  
\}  
  
  
\}

\-----------------------------------------------------------------------------------------------------------------------------------------------------------

再看Service层的  StudentService.java的实现

package org.test.servie;  
  
  
import org.test.domain.Student;  
  
  
public interface StudentService  
\{  
void storeService(Student student);  
\}

\-----------------------------------------------------------------------------------------------------------------------------------------------------------

接着是StudentServiceImpl.java的实现

package org.test.servie;  
  
  
import javax.transaction.Transactional;  
  
  
import org.springframework.beans.factory.annotation.Autowired;  
import org.springframework.stereotype.Service;  
import org.test.dao.StudentDao;  
import org.test.domain.Student;  
  
  
@Service("studentService")  
public class StudentServiceImpl implements StudentService  
\{  
  
  
@Autowired  
private StudentDao studentDao ;  
  
@Transactional  
@Override  
public void storeService(Student student)  
\{  
studentDao.store(student);  
\}  
  
\}

\------------------------------------------------------------------------------------------------------------------------------------------------------------------------

最后在写一个测试类

import org.springframework.context.ApplicationContext;  
import org.springframework.context.support.ClassPathXmlApplicationContext;  
import org.test.domain.Student;  
import org.test.servie.StudentService;  
  
  
public class Main  
\{  
public static void main(String\[\] args)  
\{  
ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext.xml");  
  
StudentService studentService = ac.getBean("studentService",StudentService.class);  
  
studentService.storeService(new Student("sunwukong"));  
\}  
\}