2、Spring的LocalSessionFactoryBean创建过程源码分析

public interface InitializingBean {
    void afterPropertiesSet() throws Exception;
}

public class LocalSessionFactoryBuilder extends Configuration{
    //...
}

public interface InitializingBean {
    void afterPropertiesSet() throws Exception;
}

//②、类LocalSessionFactoryBuilder
//显然，LocalSessionFactoryBuilder继承自org.hibernate.cfg.Configuration，那么Configuration拥有的属性，LocalSessionFactoryBuilder也具有
public class LocalSessionFactoryBuilder extends Configuration{
    //...
}

//现在主要分析LocalSessionFactoryBean
//1、看一下几个非常重要的属性值定义
public class LocalSessionFactoryBean extends... implements InitializingBean, ...{
    //数据源
    private DataSource dataSource;
    //hibernate的配置文件Xxx.cfg.xml所在的
    //位置多个可以用","隔开
    private Resource[] configLocations;
    private String[] mappingResources;
    //hibernate的映射文件位置
    private Resource[] mappingLocations;
    //hibernate的properties属性，存放了配置
    //文件中解析property标签的结果
    private Properties hibernateProperties;
    //hibernate的configuration属性
    private Configuration configuration;
    //这个sessionfactory是hibernate的sessionFactory
    private SessionFactory sessionFactory;
    
    //省略其它的属性以及setter方法...
    
    //注意这个set方法，说明当只有一个配置文件
    //的时候可以使用configLocation属性来配置，
    //最终也会被转换成configLocations
    public void setConfigLocation(Resource configLocation) {
        this.configLocations = new Resource[] {configLocation};
    }
    
    @Override
    public void afterPropertiesSet() throws IOException {
        LocalSessionFactoryBuilder sfb = new LocalSessionFactoryBuilder(this.dataSource, this.resourcePatternResolver);

        if (this.configLocations != null) {
            for (Resource resource : this.configLocations) {
                //sfb.configure(...)实际上也就是调用其父类
                //org.hibernate.cfg.Configuration的configure(...)方法
                //这里完成xxx.cfg.xml文件中property节点
                //的解析，得到一个properties
                sfb.configure(resource.getURL());
            }
        }

        //mappingResources和mappingLocations效果是一样的，
        //都会将资源转换成输入流，并调用sfb.addInputStream(...)方法
        //sfb.addInputStream(...)最终会完成xxx.cfg.xml文件的
        //非property节点解析（主要有3类：mapping、class-cache和collection-cache）
        //将解析结果放入到metadataSourceQueue中
        if (this.mappingResources != null) {
            for (String mapping : this.mappingResources) {
                Resource mr = new ClassPathResource(mapping.trim(), this.resourcePatternResolver.getClassLoader());
                sfb.addInputStream(mr.getInputStream());
            }
        }
        if (this.mappingLocations != null) {
            for (Resource resource : this.mappingLocations) {
                sfb.addInputStream(resource.getInputStream());
            }
        }

        //sfb.addProperties(...)方法会调用properties.putAll( extraProperties )方法
        //说明我们可以配置一个properties对象来达到配置xxx.cfg.xml相同的效果！！
        //两方面的配置最终都会放入到properties对象中
        if (this.hibernateProperties != null) {
            sfb.addProperties(this.hibernateProperties);
        }
        
        //省略若干其它方法...

        // 将sfb向上转型，LocalSessionFactoryBean中的configuration属性实际上
        // 就是org.hibernate.cfg.Configuration
        this.configuration = sfb;
        //在得到configuration以后，通过它来创建一个sessionFactory，
        //并赋值给sessionFactory属性（LocalSessionFactoryBean的属性）
        //在底层会调用return super.buildSessionFactory()来的到一个
        //sessionFactory，由于其父类是org.hibernate.cfg.Configuration
        //所以，相当于调用了configuration.buildSessionFactory()来生成
        //sessionFactory，这是hibernate4.0版本之前的做法，新版本已经
        //被buildSessionFactory(ServiceRegistry)所取代。 
        this.sessionFactory = buildSessionFactory(sfb);
    }
}