连接池

package intelcom.db;

import java.sql.Connection;
import java.sql.SQLException;
import java.util.Properties;

import javax.sql.DataSource;

import org.apache.commons.dbcp.BasicDataSource;
import org.apache.log4j.Logger;

/**
 * @author Administrator
 * 
 */
public class DbConn {

	// read the xml configuration file为所有对共享的一块不可改变的内存区域
	private static final String CONFIG_FILE = "db.config";

	private static final String CONFIG_URL = "url";

	private static final String CONFIG_DRIVER = "driver";

	private static final String CONFIG_USERNAME = "username";

	private static final String CONFIG_PASSWORD = "passwd";

	// get the var from configuration file初始化类成员变量
	private static String strUrl = "jdbc:oracle:thin:@1.1.1.1:1521:ynjyfx";

	private static String strDriver = "oracle.jdbc.driver.OracleDriver";

	private static String strUserName = "di_source";

	private static String strPasswd = "ynposon123";

	private static DataSource dataSource = null;

	private static Logger log = Logger.getLogger(DbConn.class);

	static {//JVM加载.class类文件时，会运行一次静态块

		try {
			Properties properties = new Properties();
			properties
					.load(DbConn.class.getResourceAsStream(CONFIG_FILE));
			strUrl = properties.getProperty(CONFIG_URL);
			strDriver = properties.getProperty(CONFIG_DRIVER); 
			strUserName = properties.getProperty(CONFIG_USERNAME);
			strPasswd = properties.getProperty(CONFIG_PASSWORD);
			
		} catch (Exception e) {
			log.info("DBConnection.java ： 初始化数据库连接参数失败 ！请检查db.config文件");
			log.info("DBConnection.java ： 出错异常：" + e.getMessage());
		}

		// get connection
		try {
			//public static void setPropertiessetProperty(String key,String value)设置指定键指示的系统属性。
			//key - 系统属性的名称。value - 系统属性的值。
			System.setProperty("jdbc.drivers", strDriver);
			Class.forName(strDriver);//jdbc的驱动不需实例化，就可以得到该驱动类的实例
			dataSource = setupDataSource(strDriver, strUserName, strPasswd,
					strUrl);
		} catch (ClassNotFoundException e) {
			log.info("DBConnection.java ： 未找到Oracle数据库驱动类！");
			log.info("DBConnection.java ： 加载驱动失败：" + e.getMessage());
		} catch (Exception sqle) {
			log.info("DBConnection.java ： 连接oracle数据库失败！");
			log.info("DBConnection.java ： 连接数据库错误：" + sqle.getMessage());
		}
	}

	// set datasource用该DataSource接口对象去存取数据库,先设置后getConnection();

	public static DataSource setupDataSource(String sDrvName, String sUserName,
			String sPwd, String connectURI) {
		BasicDataSource ds = new BasicDataSource();
		ds.setDriverClassName(sDrvName);
		ds.setUsername(sUserName);
		ds.setPassword(sPwd);
		ds.setUrl(connectURI);
		ds.setMaxActive(50);
		ds.setMaxIdle(10);
		ds.setMaxWait(10000); // 10 seconds
		return ds;
	}
    //commons-dbcp-1.2.1.jar用连接池在池中缓存连接实例，不用每次都去建立建接。
	public static Connection getConnection() throws SQLException,
			ClassNotFoundException {
		BasicDataSource bds = (BasicDataSource) dataSource;
		// log.info("DBConnection.java ： 连接池中连接数：NumActive =
		// "+bds.getNumActive()+" , 空闲连接数："+"NumIdle = "+bds.getNumIdle());
		return dataSource.getConnection();//返回前面已经设置好的dataSource表示的数据源的一个连接对象
	}

}