apache commons dbcp 学习与使用

类结构

org

  |_demo

        |_dao

             |_datasource

                        |_ConnectionTools.java

                        |_DataSourceFactory.java

                        |_PropertyDataSourceFactory.java

 

package org.demo.dao.datasource;

import javax.sql.DataSource;

/**
 * 数据源工厂
 * @author  
 * @date    2010-6-18
 * @file    org.demo.dao.datasource.DataSourceFactory.java
 */
public interface DataSourceFactory {
	// 默认数据源名称
	String defaultDataSourceName = "default";
	/**
	 * 返回默认数据源
	 * @return  dataSource or null
	 */
	DataSource getDataSource();
	/**
	 * 返回指定数据源
	 * @return  dataSource or null 
	 */
	DataSource getDataSource(String dataSourceName);
}

 

package org.demo.dao.datasource;

import java.io.IOException;
import java.io.InputStream;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Properties;

import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.sql.DataSource;

import org.apache.commons.dbcp.BasicDataSource;

/**
 * 基于属性文件的数据源工厂
 * @author  
 * @date    2010-6-18
 * @file    org.demo.dao.datasource.PropertyDataSourceFactory.java
 */
public class PropertyDataSourceFactory implements DataSourceFactory{
	// properties
	private static final String defaultFileName = "datasource.properties";
	protected Map<String,Properties> datasourceParams = new HashMap<String,Properties>();
	protected Map<String,DataSource> datasourceMap = new HashMap<String,DataSource>();
	/**
	 * 构造函数
	 * @throws  RuntimeException
	 *          If the datasource.properties could not be found or property key is illegal.
	 * @throws  IOException
	 *          If could not load properties from datasource.properties
	 */
	public PropertyDataSourceFactory()throws IOException{
		this(defaultFileName);
	}
	/**
	 * 构造函数
	 * @param fileName 
	 * 		  The resource name
	 * @throws  RuntimeException
	 *          If the resource could not be found or property key is illegal.
	 * @throws  IOException
	 *          If could not load properties from resource
	 */
	public PropertyDataSourceFactory(String fileName)throws IOException{
		// getResourceAsStream
		InputStream in = PropertyDataSourceFactory.class.getClassLoader()
						 .getResourceAsStream(fileName);
		if(in == null){
			throw new RuntimeException("The [" + fileName + "] is not found.");
		}
		// load properties from stream
		Properties props = new Properties();
		try {
			props.load(in);
		} catch (IOException e){
			throw new IOException("Could not load [" + fileName + "] config file.",e);
		}
		// analyze properties
		Iterator<Object> it = props.keySet().iterator();
		while(it.hasNext()){
			String key = (String)it.next();
			String value = props.getProperty(key);
			int dotIndex = key.indexOf('.');
			if(dotIndex < 1){
				// dotIndex must > 1 [default.driver=oracle.jdbc.driver.OracleDriver]
				throw new RuntimeException("Illegal property key [" + key + "].");
			}
			String datasourceName = key.substring(0,dotIndex);
			key = key.substring(dotIndex + 1);
			Properties params = datasourceParams.get(datasourceName);
			if(params == null){
				params = new Properties();
				datasourceParams.put(datasourceName, params);
			}
			params.put(key,value);
		}
	}
	/**
	 * 返回默认数据源
	 * @return  dataSource or null
	 */
	public DataSource getDataSource(){
		return getDataSource(defaultDataSourceName);
	}
	/**
	 * 返回指定数据源
	 * @param  dataSourceName
	 *         The dataSource name
	 * @return  dataSource or null
	 */
	public DataSource getDataSource(String dataSourceName){
		DataSource datasource = datasourceMap.get(dataSourceName);
		if(datasource != null){
			return datasource;
		}
		datasource = createDataSource(datasourceParams.get(dataSourceName));
		if(datasource != null){
			datasourceMap.put(dataSourceName, datasource);
		}
		return datasource;
	}
	/**
	 * 创建一个数据源
	 * @param props
	 * @return  dataSource or null
	 * @throws  IllegalArgumentException
	 *          If props is null
	 */
	protected DataSource createDataSource(Properties props){
		if(props == null){
			throw new IllegalArgumentException("props can not be null.");
		}
		if(props.getProperty("jndiName") != null){
			DataSource jndiDataSource = getJndiDataSource(props);
			if(jndiDataSource != null){
				return jndiDataSource;
			}
		}
		BasicDataSource dataSource = new BasicDataSource();
		// required
		dataSource.setDriverClassName(props.getProperty("driverClassName"));
		dataSource.setUrl(props.getProperty("url"));
		dataSource.setUsername(props.getProperty("username",""));
		dataSource.setPassword(props.getProperty("password",""));
		// options
		dataSource.setInitialSize(Integer.parseInt(props.getProperty("initialSize","3")));
		dataSource.setMaxActive(Integer.parseInt(props.getProperty("maxActive", "10")));
		dataSource.setMaxIdle(Integer.parseInt(props.getProperty("maxIdle","5")));
		dataSource.setMaxWait(Long.parseLong(props.getProperty("maxWait","-1")));
		dataSource.setValidationQuery(props.getProperty("validationQuery"));
		return dataSource;
	}
	/**
	 * 返回 jndi 数据源
	 * @param  props
	 * @return  dataSource or null
	 */
	protected DataSource getJndiDataSource(Properties props){
		String jndiName = props.getProperty("jndiName");
		String inContainer = props.getProperty("inContainer");
		String prefix = "java:comp/env/";
		if(!jndiName.startsWith(prefix) && "true".equals(inContainer)){
			jndiName = prefix + jndiName;
		}
		// 
		DataSource jndiDataSource = null;
		Context context = null;
		try{
			context = new InitialContext(props);
			jndiDataSource = (DataSource)context.lookup(jndiName);
			if(jndiDataSource != null){
				return jndiDataSource;
			}
		} catch (NamingException e){
			// ignore
		} finally {
			try{
				if(context != null){
					context.close();
				}
			} catch (NamingException e){
				// ignore
			}
		}
		return jndiDataSource;
	}
}

 

package org.demo.dao.datasource;

import java.io.IOException;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import javax.sql.DataSource;

/**
 * 连接工具
 * @author  
 * @date    2010-6-18
 * @file    org.demo.dao.datasource.ConnectionTools.java
 */
public abstract class ConnectionTools {
	// 数据源工厂
	protected static DataSourceFactory _factory;
	static {
		try {
			_factory = new PropertyDataSourceFactory();
		} catch(IOException e){
			e.printStackTrace();
		}
	}
	/**
	 * 返回默认数据源的连接
	 * @return  connection or null
	 */
	public static Connection getConnection(){
		return getConnection(DataSourceFactory.defaultDataSourceName);
	}
	/**
	 * 返回指定数据源的连接
	 * @param dataSourceName
	 *        The dataSource name
	 * @return  connection or null
	 */
	public static Connection getConnection(String dataSourceName){
		DataSource datasource = _factory.getDataSource(dataSourceName);
		Connection conn = null;
		if(datasource != null){
			try{
				conn = datasource.getConnection();
			} catch (SQLException e){
				e.printStackTrace();
			}
		}
		return conn;
	}
	/**
	 * 关闭连接对象
	 * @param rset
	 * 		  ResultSet
	 * @param stmt
	 *        Statement
	 * @param conn
	 *        Connection
	 */
	public static void close(ResultSet rset,Statement stmt,Connection conn){
		try { if (rset != null) rset.close(); } catch (Exception e) {}
		try { if (stmt != null) stmt.close(); } catch (Exception e) {}
		try { if (conn != null) conn.close(); } catch (Exception e) {}
	}
}

 

# datasource.properties

# oracle
default.driverClassName=oracle.jdbc.driver.OracleDriver
default.url=jdbc:oracle:thin:@localhost:1521:test
default.username=scott
default.password=tiger
# 

 

package org.demo.dao;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.Statement;

import org.demo.dao.datasource.ConnectionTools;
// 
// library dependencies:
//  * commons-dbcp-1.3.jar   [http://commons.apache.org/dbcp/download_dbcp.cgi]
//  * commons-pool-1.5.4.jar [http://commons.apache.org/pool/download_pool.cgi]
// 
/**
 * @author  
 * @date    2010-6-18
 * @file    org.demo.dao.Main.java
 */
public class Main {

	/**
	 * @param args
	 */
	public static void main(String[] args)throws Exception{
		// get connection
		Connection conn = ConnectionTools.getConnection();
		// execute business operations
		Statement stmt = null;
		ResultSet rset = null;
		stmt = conn.createStatement();
		rset = stmt.executeQuery("select 1 from dual");
		int cols = rset.getMetaData().getColumnCount();
		while(rset.next()){
			for(int i=1;i<=cols;i++){
				System.out.print("\t" + rset.getObject(i));
			}
			System.out.println("");
		}
		// close connection
		ConnectionTools.close(rset, stmt, conn);
	}

}