在Spring 集成 Hibernate 的JPA方式中，需要在persistence配置文件中定义每一个实体类，这样非常地不方便，2种方法可以解决此问题：
这2种方式都可以实现不用在persistence.xml文件中配置每一个实体类，从而免去每个Entity都要在persistence.xml文件中配置的烦恼，但是这种方式Entity实体类的主键字段注解@ID要放到 getXXX()方法上，否则不认。
方式1：
修改“LocalContainerEntityManagerFactoryBean”的配置，如下：
<bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
<property name="packagesToScan" value="com.sunitjy.model.entityName" />
<property name="jpaVendorAdapter">
<bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter"/>
</property>
<property name="jpaProperties">
<props>
<prop key="hibernate.connection.driver_class">${jdbc.driverClassName}</prop>
<prop key="hibernate.connection.url">${jdbc.url}</prop>
<prop key="hibernate.connection.username">${jdbc.username}</prop>
<prop key="hibernate.connection.password">${jdbc.password}</prop>
<prop key="hibernate.c3p0.min_size">10</prop>
<prop key="hibernate.hbm2ddl.auto">true</prop>
<prop key="hibernate.dialect">${hibernate.dialect}</prop>
</props>
</property>
</bean>
方式1没有使用 persistence 这个配置文件，注意咯！
方式2：
修改“LocalContainerEntityManagerFactoryBean”的配置，如下：
<bean id="entityManagerFactory"
class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
<!-- <property name="persistenceUnitName" value="pro_persistence"></property>-->
<property name="dataSource" ref="dataSource"></property>
<property name="persistenceXmlLocation" value="classpath*:pro_core/jpa_persistence.xml"></property>
<property name="packagesToScan">
<list>
<value>com.paic.lfex.model</value>
<value>com.lfex.sdp.core.model</value>
<value>com.paic.lfex.core.pro</value>
</list>
</property>
<property name="jpaVendorAdapter">
<bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter" />
</property>
</bean>
persistence.xml配置文件内容：
<persistence xmlns="http://java.sun.com/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistencehttp://java.sun.com/xml/ns/persistence/persistence_1_0.xsd"
version="1.0">
<persistence-unit name="pro_persistence"
transaction-type="RESOURCE_LOCAL">
<provider>org.hibernate.ejb.HibernatePersistence</provider>
<properties>
<property name="hibernate.dialect" value="org.hibernate.dialect.Oracle10gDialect" />
<property name="current_session_context_class" value="thread" />
<!--<property name="hibernate.hbm2ddl.auto" value="update" /> -->
<!--<property name="hibernate.show_sql" value="true" />-->
<!--<property name="hibernate.format_sql" value="true" />-->
</properties>
</persistence-unit>
</persistence>
方式2使用了 persistence 配置文件，去掉“persistenceUnitName”属性，添加“packagesToScan”属性，persistence.xml配置文件中的persistence-unit名字照样保留，但是 persistence 配置文件中不需要对实体类进行配置，会自动识别。
为什么去掉“persistenceUnitName”属性就可以自动识别实体了呢？看一下Spring的源码就知道了：
类名：org.springframework.orm.jpa.persistenceunit.DefaultPersistenceUnitManager
代码段：
private List<SpringPersistenceUnitInfo> readPersistenceUnitInfos() {List<SpringPersistenceUnitInfo> infos = new LinkedList<SpringPersistenceUnitInfo>();boolean buildDefaultUnit = (this.packagesToScan != null || this.mappingResources != null);PersistenceUnitReader reader = new PersistenceUnitReader(this.resourcePatternResolver, this.dataSourceLookup);SpringPersistenceUnitInfo[] readInfos = reader.readPersistenceUnitInfos(this.persistenceXmlLocations);for (SpringPersistenceUnitInfo readInfo : readInfos) {infos.add(readInfo);if (this.defaultPersistenceUnitName != null &&this.defaultPersistenceUnitName.equals(readInfo.getPersistenceUnitName())) {buildDefaultUnit = false;}}if (buildDefaultUnit) {infos.add(buildDefaultPersistenceUnitInfo());}return infos;} |