Hibernate根据方言dialect动态连接多数据库

 

Hibernate根据方言dialect动态连接多数据库

由于最近需要在web项目中动态链接不同地址的数据库，且要链接的子数据库的信息在总数据库（即web项目的主数据库）的表中，所以动手写了一个类。

web项目试用了hibernate，动态生成的子数据库链接打算也用hibernate，虽然动态生成的sessionfactory类，以及Configuration配置没有子数据库的对象关系映射，但是使用 native SQL 也方便。

 

请看后来写的改进篇，有什么建议请留言------------

  Hibernate动态连接多数据库改进篇

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代码如下：

public class TempSessionFactory {

    /** 
     * Location of hibernate.cfg.xml file.
     * Location should be on the classpath as Hibernate uses  
     * #resourceAsStream style lookup for its configuration file. 
     * The default classpath location of the hibernate config file is 
     * in the default package. Use #setConfigFile() to update 
     * the location of the configuration file for the current session.   
     */
    //private static String CONFIG_FILE_LOCATION = "/hibernate.cfg.xml";
	private final ThreadLocal<Session> threadLocal = new ThreadLocal<Session>();
    private Configuration configuration = new Configuration(); 
    private org.hibernate.SessionFactory sessionFactory;
    //private static String configFile = CONFIG_FILE_LOCATION;

/*	static {
    	try {
			configuration.configure(configFile);
			sessionFactory = configuration.buildSessionFactory();
		} catch (Exception e) {
			System.err
					.println("%%%% Error Creating SessionFactory %%%%");
			e.printStackTrace();
		}
    }*/

	public void setConfiguration(String dialect, String driverClass,
			String ipAddress, String port, String dataBaseName,
			String username, String password) {
		String connection_url = "";

		Configuration configuration = new Configuration();
		if (dialect.indexOf("MySQL") > -1) {
			System.out.println("%%%% DataBase type is MySql %%%%");
			connection_url = "jdbc:mysql://" + ipAddress + "/" + dataBaseName;
		} else if (dialect.indexOf("SQLServer") > -1) {
			System.out.println("%%%% DataBase type is SQLServer %%%%");
			connection_url = "jdbc:sqlserver://" + ipAddress + ":" + port
					+ ";DataBaseName=" + dataBaseName;
		} else if (dialect.indexOf("Oracle") > -1) {
			System.out.println("%%%% DataBase type is Oracle %%%%");
			connection_url = "jdbc:oracle:thin:@" + ipAddress + ":" + port
					+ ":" + dataBaseName;
			// configuration.setProperty("hibernate.connection.oracle.jdbc.V8Compatible","true");
		}

		configuration.setProperty("hibernate.dialect", dialect);
		configuration.setProperty("hibernate.connection.url", connection_url);
		configuration.setProperty("hibernate.connection.driver_class",
				driverClass);
		configuration.setProperty("hibernate.connection.username", username);
		configuration.setProperty("hibernate.connection.password", password);
		// configuration.setProperty("hibernate.default_schema", "dbo");
		// configuration.setProperty("hibernate.default_catalog", dataBaseName);
		// configuration.setProperty("hibernate.show_sql", "true");
		this.configuration = configuration;
	}
	/**
     * Returns the ThreadLocal Session instance.  Lazy initialize
     * the <code>SessionFactory</code> if needed.
     *
     *  @return Session
     *  @throws HibernateException
     *  
     */
    public Session getSession() throws HibernateException {
        Session session = (Session) threadLocal.get();
		if (session == null || !session.isOpen()) {
			if (sessionFactory == null) {
				rebuildSessionFactory();
			}
			session = (sessionFactory != null) ? sessionFactory.openSession()
					: null;
			threadLocal.set(session);
		}

        return session;
    }

	/**
     *  Rebuild hibernate session factory
     *
     */
	public void rebuildSessionFactory() {
		try {
			//configuration.configure(configFile);
			sessionFactory = this.configuration.buildSessionFactory();
		} catch (Exception e) {
			System.err
					.println("%%%% Error Creating SessionFactory %%%%");
			e.printStackTrace();
		}
	}

	/**
     *  Close the single hibernate session instance.
     *
     *  @throws HibernateException
     */
    public void closeSession() throws HibernateException {
        Session session = (Session) threadLocal.get();
        threadLocal.set(null);

        if (session != null) {
            session.close();
        }
    }

	/**
     *  return session factory
     *
     */
	public org.hibernate.SessionFactory getSessionFactory() {
		return sessionFactory;
	}

	/**
     *  return session factory
     *
     *	session factory will be rebuilded in the next call
     */
/*	public static void setConfigFile(String configFile) {
		HibernateSessionFactory.configFile = configFile;
		sessionFactory = null;
	}*/

	/**
     *  return hibernate configuration
     *
     */
	public Configuration getConfiguration() {
		return configuration;
	}
}

测试类代码：
在 databasename1 库中建 testtable表，字段id,name2个
在 databasename2 库中建 testtable2表，字段id,name2个

public class TestCase1 {

	public static void main(String[] args) {
		
		try{
			
			Configuration configuration1 = new Configuration();			
			TempSessionFactory tempSessionFactory1 = new TempSessionFactory(configuration1);
			tempSessionFactory1.setConfiguration("org.hibernate.dialect.SQLServerDialect","com.microsoft.sqlserver.jdbc.SQLServerDriver",
					"jdbc:sqlserver://*1.*1.*1.*1","1433","databasename1","sa","sa");
			Session session1=tempSessionFactory1.getSession();
			Transaction tx1 = session1.beginTransaction();
			Query query1 = session1.createSQLQuery("select  name as  aaa  from testtable ").setResultTransformer(
					Transformers.ALIAS_TO_ENTITY_MAP);
			Map obj1 = (Map)query1.setMaxResults(1).uniqueResult();
			System.out.println("fd1111===="+obj1.get("aaa"));
			
			Configuration configuration2 = new Configuration();			
			TempSessionFactory tempSessionFactory2 = new TempSessionFactory(configuration2);
			tempSessionFactory2.setConfiguration("org.hibernate.dialect.SQLServerDialect","com.microsoft.sqlserver.jdbc.SQLServerDriver",
					"jdbc:sqlserver://*2.*2.*2.*2","1433","databasename2","sa","sa");
			Session session2=tempSessionFactory2.getSession();
			Transaction tx2 = session2.beginTransaction();
			Query query2 = session2.createSQLQuery("select  name as  aaa  from testtable2 ").setResultTransformer(
					Transformers.ALIAS_TO_ENTITY_MAP);
			Map obj2 = (Map)query2.setMaxResults(1).uniqueResult();
			System.out.println("fd2222===="+obj2.get("aaa"));
			
	
		}catch (Exception e) {
			System.err.println(e);
			// TODO: handle exception
		}
	}
}

 

请看后来写的改进篇--------------------

 

  Hibernate动态连接多数据库改进篇

 

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评论

2 楼 feicer 2010-01-11  

注意：在 oracle中 使用 native sql 查询，别名自动会变成 大写的，

select  name as  aaa  from testtable2 

会变成

select  name as  AAA from testtable2 

故

System.out.println("fd2222===="+obj2.get("AAA"));

   才可以

1 楼 feicer 2010-01-07  

高手们，有没有更好的办法写 TempSessionFactory  类，有的话，留言说一下啊。。。