daomanager.java

ESQL包 PostgreSQL jsp servlet javaBean 数据库访问 存取数据

package com.dao;

import java.lang.reflect.Modifier;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.sql.DataSource;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import zuojie.esql.ESQL;


public class DaoManager
{
	public final static int READ_COMMITTED = Connection.TRANSACTION_READ_COMMITTED;
	public final static int SERIALIZABLE = Connection.TRANSACTION_SERIALIZABLE;

	private static Log log = LogFactory.getLog(DaoManager.class);

	private static Map<String, DaoManager> managers = new HashMap<String, DaoManager>();
	
	public static DaoManager getInstance(String name)
	{
		return managers.get(name);
	}

	public static DaoManager getInstance()
	{
		return managers.get("default");
	}
	
	public static void initialize(DataSource source) throws Exception
	{
		// 本地默认数据源
		DaoManager manager = new DaoManager();

		manager.setDaoPackageName("com.dao");
		manager.setDatabase(Class.forName("com.dao.PostgreSQL"));
		manager.setDataSource(source);
		manager.startup();
		managers.put("default", manager);

	}
	
	//====================================================================
	
	private String name;
	private String daoPackageName;
	private Class<?> database;			// Dao对象应该实现的类, 用于区别调入用于不同数据库的Dao
	private DataSource dataSource;

	private ESQL esql;

	public DaoManager()
	{
	}
	
	private Map<Class<?>, Object> daos = new HashMap<Class<?>, Object>();

	/** 通过连接池数据源初始化 */
	public void startup() throws Exception
	{
		managers.put(name, this);

		log.info("启动DAO管理器");
		
		// 声明一个ESQL对象
		
		esql = new ESQL(dataSource);

		// 设置数据存取对象
		JavaPackageExplorer explorer = new JavaPackageExplorer(daoPackageName);
		List<String> list = explorer.explore();
		for (String s : list)
		{
			log.info(s);
			register(s);
		}
	}

	/** 注册一个DAO对象 */
	private void register(String name)
	{
		try
		{
			Class<?> type = Class.forName(name);
			if (type.equals(BaseDao.class)) return;
			if (!BaseDao.class.isAssignableFrom(type)) return;
			if (!database.isAssignableFrom(type)) return;
			//排除抽象类
			if (Modifier.isAbstract(type.getModifiers())) return ;

			log.info("注册DAO类: " + name);

			BaseDao dao = (BaseDao) type.newInstance();
			dao.setEsql(esql);

			Class<?>[] cs = type.getInterfaces();
			for (Class<?> c : cs)
			{
				daos.put(c, dao);
			}
		}
		catch (Exception e)
		{
			log.error("注册DAO类失败: " + name, e);
		}
	}

	public <T> T getDao(Class<T> type)
	{
		Object dao = daos.get(type);
		if (dao == null) throw new RuntimeException("指定的DAO不存在: " + type.getCanonicalName());
		return type.cast(dao);
	}

	public ESQL getEsql()
	{
		return esql;
	}
	
	/** 开始事务 */
	public void begin(int isolation) throws Exception
	{
		try
		{
			esql.startTransaction(isolation);
		}
		catch (Exception e)
		{
			throw new Exception("开始事务错误", e);
		}
	}

	public void begin() throws Exception
	{
		begin(DaoManager.READ_COMMITTED);
	}

	/** 提交当前事务 */
	public void commit() throws Exception
	{
		try
		{
			esql.commitTransaction();
		}
		catch (Exception e)
		{
			throw new Exception("提交事务错误", e);
		}
	}

	/** 结束当前事务。如果没有提交，就回滚 */
	public void end()
	{
		try
		{
			esql.endTransaction();
		}
		catch (Exception e)
		{
		}
	}

	public void setTransactionIsolation(int isolation) throws Exception
	{
		try
		{
			esql.setTransactionIsolation(isolation);
		}
		catch (SQLException e)
		{
			throw new Exception("设置事务隔离度错误", e);
		}
	}

	public void setDaoPackageName(String daoPackageName)
	{
		this.daoPackageName = daoPackageName;
	}

	public void setDatabase(Class<?> database)
	{
		this.database = database;
	}

	public void setDataSource(DataSource dataSource)
	{
		this.dataSource = dataSource;
	}

	public String getName()
	{
		return name;
	}

	public void setName(String name)
	{
		this.name = name;
	}
}