Spring整合Hibernate：利用LocalSessionFactoryBean类读取hibernate配置

配置示例

<bean id="sessionFactory" class="org.springframework.orm.hibernate4.LocalSessionFactoryBean" destroy-method="destroy">    <property name="dataSource" ref="dataSource"/>    <property name="configLocation" value="classpath:hibernate.cfg.xml"/>    <property name="hibernateProperties">        <props>            <prop key="hibernate.dialect">${hibernate.dialect}</prop>            <prop key="hibernate.query.substitutions">true 'Y', false 'N'</prop>            <prop key="hibernate.cache.use_second_level_cache">true</prop>            <prop key="hibernate.cache.provider_class">org.hibernate.cache.EhCacheProvider</prop>            <!-- Hibernate Search index directory -->            <prop key="hibernate.search.default.indexBase">${app.search.index.basedir}</prop>            <prop key="hibernate.temp.use_jdbc_metadata_defaults">false</prop>        </props>        <!-- Turn batching off for better error messages under PostgreSQL -->        <!-- hibernate.jdbc.batch_size=0 -->    </property></bean>

源码分析

以上是利用Spring读取Hibernate的配置文件hibernate.cfg.xml来构建sessessionFactory.

我们都知道，Spring容器在帮我们初始化一个类对象（此地方是LocalSessionFactoryBean）后。
如果此类实现了InitializingBean接口，那么该类会自动调用afterPropertiesSet方法。

让我们看看LocalSessionFactoryBean的afterPropertiesSet源码

public void afterPropertiesSet() throws IOException {    LocalSessionFactoryBuilder sfb = new LocalSessionFactoryBuilder(this.dataSource, this.resourcePatternResolver);    if (this.configLocations != null) {        for (Resource resource : this.configLocations) {            // Load Hibernate configuration from given location.            sfb.configure(resource.getURL());        }    }    ...//中间部分代码，已省略。    // Build SessionFactory instance.    this.configuration = sfb;    this.sessionFactory = buildSessionFactory(sfb);}

LocalSessionFactoryBuilder类继承自org.hibernate.cfg.Configuration

也就是说，初始化完LocalSessionFactoryBean类后，
也就是把配置都读取后，Spring开始调用Hibernate的Configuration里的configure方法，
读取hibernate.cfg.xml.并build好sessessionFactory放在Spring容器中。