整理されたc 3 p 0ツールクラス

package db.c3p0;

import java.sql.Connection;
import java.sql.SQLException;

import com.mchange.v2.c3p0.ComboPooledDataSource;

/**
 * c3p0     
 * *     ：   
 *  driveClassName：JDBC         ;
 *  maxActive：            ;
 *  minActive：            ;
 *  initialPoolSize：                     ;
 *  maxWait：      ，    ;
 *  password：    ;
 *  url： JDBC URL  ;
 *  user：    ;
 *  maxIdleTime：      ,             。  0     ;
 *  acquireIncrement：             c3p0          ;
 *  idleConnectionTestPeriod：                 ;
 *  acquireRetryAttempts：                      ;
 *  testConnectionOnCheckout：                 。    true     connection     
  							             。    idleConnectionTestPeriod automaticTestTable  
  							               ;
 *  breakAfterAcquireFailure：                             。          
  							   ，      getConnection()           。    true，       
  							                       。;
 *  maxStatements：JDBC     ，           PreparedStatements  。       statements  
  				       connection        。                   。  
  				     maxStatements maxStatementsPerConnection  0，      。;
  				   
 * @author dxz
 *
 */
public class DBHelp {
	private static ComboPooledDataSource dataSource = null;
	private static String username = "jspcms";
	private static String password = "jspcms";
	private static String url = "jdbc:mysql://localhost:3306/jspcms";
	private static String drive = "com.mysql.jdbc.Driver";
	private static int maxActive = 30;
	private static int minActive = 2;
	private static int initialPoolSize = 2;
	private static int maxIdleTime = 60;
	private static int acquireIncrement = 5;
	private static int maxStatements = 0;
	private static int idleConnectionTestPeriod = 60;
	private static int acquireRetryAttempts = 30;
	private static boolean breakAfterAcquireFailure = true;
	private static boolean testConnectionOnCheckout = false;
	
	private Connection conn = null;
	
	/**
	 *       
	 * @throws Exception
	 */
	private void init() throws Exception{
		  if(dataSource == null){
			  dataSource = new ComboPooledDataSource(); 
			  dataSource.setDriverClass(this.drive); 
			  dataSource.setJdbcUrl(this.url); 
			  dataSource.setUser(this.username); 
			  dataSource.setPassword(this.password); 
			  dataSource.setMaxPoolSize(this.maxActive); 
			  dataSource.setMinPoolSize(this.minActive);
			  dataSource.setInitialPoolSize(this.initialPoolSize);
			  dataSource.setMaxIdleTime(this.maxIdleTime);
			  dataSource.setAcquireIncrement(this.acquireIncrement);
			  dataSource.setMaxStatements(this.maxStatements); 
			  dataSource.setIdleConnectionTestPeriod(this.idleConnectionTestPeriod); 
			  dataSource.setAcquireRetryAttempts(this.acquireRetryAttempts); 
			  dataSource.setBreakAfterAcquireFailure(this.breakAfterAcquireFailure);
			  dataSource.setTestConnectionOnCheckout(this.testConnectionOnCheckout);
		  }
	}
	
	/**
	 *        
	 * @return
	 * @throws Exception
	 */
	public Connection getConnection() throws Exception{
		 
		 try {
			  if(dataSource == null){
				  this.init();
			  }
			  this.conn = (Connection) dataSource.getConnection();
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (Exception e) {
			// TODO: handle exception
			e.printStackTrace();
			throw e;
		}
	      
	    return conn;
		
	}
	
	/**
	 *        
	 */
	public void closeConnection(){
		if(this.conn != null){
			try {
				this.conn.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
	}
}