hibernate框架下配置多個數據庫

當我們在同一個專案中需要同時連線多個數據庫時，在hibernate框架下的我們可以通過配置多個sessionFactory與多個連線池配置實現獲取不同資料庫的連線session物件。

初始化hibernate的sessionFactory

通過spring全註解方式初始化hibernate
配置如下：

@Bean
public DataSource druidDataSourceForMySQL() {
    DruidDataSource database = new DruidDataSource();
    database.setDriverClassName
 
(environment.getProperty("jdbc.mysql.driverClassName"));
    database.setUrl(environment.getProperty("jdbc.mysql.url"));
    database.setUsername(environment.getProperty("jdbc.mysql.username"));
    database.setPassword(environment.getProperty("jdbc.mysql.password"));
    database.setDefaultAutoCommit
 
(false);
    database.setTimeBetweenEvictionRunsMillis(3600000);
    database.setMinEvictableIdleTimeMillis(3600000);
    database.setInitialSize(1);
    return database;
    }

@Bean(name = "sessionFactory")
@Profile("mysql_develop")
public LocalSessionFactoryBean sessionFactoryForMySQL() {
    LocalSessionFactoryBean sessionFactory = new LocalSessionFactoryBean();
 

    // 設定資料來源
    sessionFactory.setDataSource(druidDataSourceForMySQL());
    // 設定entity所在包，用於自動掃描
    sessionFactory.setPackagesToScan(new String[]{"com.hcicloud.sap.model"});
    // 設定Hibernate的配置屬性
    Properties props = new Properties();
    props.setProperty("hibernate.dialect", environment.getProperty("hibernate.mysql.dialect"));
    props.setProperty("hibernate.default_schema", environment.getProperty("hibernate.mysql.default_schema"));

    props.setProperty("hibernate.show_sql", environment.getProperty("hibernate.show_sql"));
    props.setProperty("hibernate.format_sql", environment.getProperty("hibernate.format_sql"));
    props.setProperty("hibernate.hbm2ddl.auto", environment.getProperty("hibernate.hbm2ddl.auto"));
    props.setProperty("hibernate.use_sql_comments", environment.getProperty("hibernate.use_sql_comments"));
props.setProperty("hibernate.connection.deferPrepares", "false");
    props.setProperty("hibernate.cache.provider_class", "org.hibernate.cache.EhCacheProvider");
    props.setProperty("hibernate.jdbc.batch_size", environment.getProperty("hibernate.jdbc.batch_size"));
    props.setProperty("hibernate.jdbc.fetch_size", environment.getProperty("hibernate.jdbc.fetch_size"));
    // 強制Hibernate按照被更新資料的主鍵，為SQL更新排序。這麼做將減少在高併發系統中事務的死鎖。
    props.setProperty("hibernate.order_updates", "true");
    // session在事務完成後將被自動清洗(flush)
    props.setProperty("hibernate.transaction.flush_before_completion", "true");
    props.setProperty("hibernate.query.substitutions", environment.getProperty("hibernate.query.substitutions"));
    props.setProperty("hibernate.default_batch_fetch_size", environment.getProperty("hibernate.default_batch_fetch_size"));
    // 為單向關聯(一對一, 多對一)的外連線抓取（outer join fetch）樹設定最大深度. 值為0意味著將關閉預設的外連線抓取
    props.setProperty("hibernate.max_fetch_depth", environment.getProperty("hibernate.max_fetch_depth"));
    props.setProperty("hibernate.generate_statistics", environment.getProperty("hibernate.generate_statistics"));
    props.setProperty("hibernate.bytecode.use_reflection_optimizer", environment.getProperty("hibernate.bytecode.use_reflection_optimizer"));
    props.setProperty("hibernate.cache.use_second_level_cache", "true");
    props.setProperty("hibernate.cache.use_query_cache", "true");
    props.setProperty("hibernate.cache.region.factory_class", "org.hibernate.cache.EhCacheRegionFactory");
    props.setProperty("net.sf.ehcache.configurationResourceName", environment.getProperty("hibernate.net.sf.ehcache.configurationResourceName"));
    props.setProperty("hibernate.cache.use_structured_entries", environment.getProperty("hibernate.cache.use_structured_entries"));
    sessionFactory.setHibernateProperties(props);

    return sessionFactory;
}

注入sessionFactory

通過如讓的配置我們獲取了指定連線池的sessionFactory
在我們編寫的hibernateDao中通過@Autowired與@Qualifier(byName)將sessionFactory進行載入獲取session物件
程式碼如下：

@Autowired
@Qualifier("sessionFactory")
public void setSessionFactory(final SessionFactory sessionFactory) {
    this.sessionFactory = sessionFactory;
}

獲取session物件

不同的資料庫配置不同的hibernateDao類，在操作不同的資料庫時，直接繼承指定的hibernateDao即可。
通過getSession方法獲取session物件進行查詢：

public Session getSession() {
    return sessionFactory.getCurrentSession();
}

getSession().create...  獲取criteria   獲取HQL查詢物件  獲取sqlQuery物件