import java.sql.Connection;import java.sql.SQLException;import javax.naming.Context;import javax.naming.InitialContext;import javax.naming.NamingException;import javax.sql.DataSource;public class DBUtil {	/**	 * 在tomcat的server.xml中配置datasource

* /	 
    		  
     		
    	 	 */	private static DataSource ds = null;	private Connection conn; 	public Connection getConnection () throws Exception{		try {			if (ds == null) {				initDS();			}			conn = ds.getConnection();			conn.setAutoCommit(false);			return conn ;		} catch (SQLException e) {			e.printStackTrace();			throw e;		}	 	}	//通过jndi获取ds	private  void initDS () throws Exception {		try {			Context initContext = new InitialContext ();			Context envContext= (Context) initContext.lookup("java:/comp/env");			ds = (DataSource) envContext.lookup("jdbc/MySQL");			//return ds ;				}catch (NamingException e){			e.printStackTrace();		}catch (ClassCastException e2){			e2.printStackTrace();		}		}}