dbconnectionmanager.java

Java数据库连接池的应用

package com.hoperun.connectionPool;
/**
 * DBConnectionManager
 *@author zhou_chenxi
 */

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.Driver;
import java.sql.DriverManager;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Properties;

public class DBConnectionManager {
    //The only instance of the class DBConnectionManager.
	static private DBConnectionManager instance;
    //The number of clinents.
	static private int clients;
    //A container丆preserve the drivers of the datebase.
	private ArrayList drivers=new ArrayList();
    //Access the name of the target in the connectionpool and this target itself,
	//in the form of name/value.
	private HashMap pools = new HashMap();
	
	/**
	 * If the only instance has been created丆return it;
	 * else create it in the init() from tje privte function.
	 */
	static synchronized public DBConnectionManager getInstance(){
		if (instance == null) { 
			instance = new DBConnectionManager(); 
		} 
		return instance;
	}
		
    /**
     * Build the private function in order to prevent 
     * other targets from establishing this kind of instance. 
     * @call init()
     */
	private DBConnectionManager(){
		 init(); 
	}
	
    /**
     * Free a connection by the name of the connectionpool.
     * @param name
     * @param con
     */
	public void freeConnection(String name,Connection con){
		//Get the connectionpool by its name.
		DBConnectionPool poolTemp = (DBConnectionPool) pools.get(name); 
		if (poolTemp!= null) { 
			//Free the connection.
			poolTemp.freeConnection(con); 
			System.out.println("Free the connection乧乧");
			clients--;
            //For test,show the connections.
			System.out.println("The number of free connections :"+DBConnectionPool.freeConnections.size());
		} 
	}
    /**
     * get a connection from the connectionpool by the name
     * @call getConnection(time).Put an acquiescence value myself.
     * @param name
     */
	public Connection getConnection(String name){
    	Connection con=null;
    	//Get the connectionpool.
    	DBConnectionPool poolTemp = (DBConnectionPool) pools.get(name);
    	//Get the connection.Acquiescence the timeout is 10000.
    	if(poolTemp!=null){
    		con=poolTemp.getConnection(10000);
    	if (con!= null)
    		System.out.println("Get the connection乧乧");
    	}
    	clients++;
    	//For test.Show the number of the clients.
    	System.out.println("The clients' number is:"+clients);
    	return con; 
     } 
    	 
    /**
     * get a connection from the connectionpool by the name and time,
     * @call getConnection(time)
     * @param name
     * @param time
     */
	public Connection getConnection(String name,long time){
		Connection con=null;
        //Get the connectionpool.
    	DBConnectionPool poolTemp = (DBConnectionPool) pools.get(name);
    	//Get the connection.
    	if(poolTemp!=null){
    		con=poolTemp.getConnection(time);
    	if (con!= null)
    		System.out.println("Get the connection乧乧");
    	}
    	clients++;
    	//For test.Show the number of the clients.
    	System.out.println("The clients' number is:"+clients);
    	return con; 
	}
	
	/**
	 * release all of the resource
	 */
	public synchronized void release(){
		if (clients!= 0){ 
			return; 
		}
		//release the pools
		Iterator allPools = pools.keySet().iterator(); 
		while (allPools.hasNext()) { 
			DBConnectionPool pool = (DBConnectionPool) pools.get(allPools.next()); 
			if(pool!=null)
				pool.release();
			System.out.println("Release the connectionpool乧乧");
		} 
		pools.clear();
		/**release the drivers
		Iterator allDrivers = drivers.iterator();
		while (allDrivers.hasNext()) { 
			Driver driver = (Driver) allDrivers.next(); 
			try { 
				DriverManager.deregisterDriver(driver); 
				} 
			catch (SQLException e) { 
				e.printStackTrace();
			} 
		}
		System.out.println("Drivers released done.");*/
		System.out.println("All source released.");
	}
	
    /**
     * Create one or more ConnectionPools according to the infomation of property file.
     * @param props
     */
	private void createPools(Properties props){
		String url=props.getProperty("URL").trim();
		String user=props.getProperty("USER").trim();
  	    String name=props.getProperty("NAME").trim();
  	    String password=props.getProperty("PASSWORD").trim();
  	    String maxcon=props.getProperty("MAXCONN").trim();
  	    int maxConn=Integer.valueOf(maxcon).intValue();
  	    if (maxConn<=0){
  		  System.out.println("The connectins are full.");
  		  maxConn=1;
  	  }
  	  DBConnectionPool poolTemp = new DBConnectionPool(name, url,    
                user, password, maxConn);
  	  //Put the pool's info to the Hashmap.
  	  pools.put(name, poolTemp);
	}
	
	/**
	 * Initial the example of the ConnectionPool.
	 */
	private void init(){
		Properties propsTemp = new Properties();
		try {
            //set the filepath of the ORCALE.Properties.
			InputStream fileinputstream = new 
			FileInputStream("./config/ORCALE.Properties");
			//Load the properties file.
			propsTemp.load(fileinputstream);
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
		loadDrivers(propsTemp);
  	    createPools(propsTemp);
	}
	
    /**
     * Load the properties driver.
     * @param props
     */
	private void loadDrivers(Properties props){
		String driverClasses = props.getProperty("DRIVER").trim(); 
		try { 
			Driver driver = (Driver) 
			Class.forName(driverClasses).newInstance(); 
			DriverManager.registerDriver(driver); 
			drivers.add(driver); 
			} 
		catch (Exception e) { 
			e.printStackTrace();
			} 
		}
	}