JAVA并发- 典型连接池的实现

package com.xyz.connpool;

public interface IConnection {
	/**
	 * 关闭当前连接
	 */
	public void close();
	/**
	 * 销毁当前连接
	 */
	public void destroy();
	//应该具备的其他方法
}

public class Connection implements IConnection {
	private String name;
	private IConnPool connPool;
	public Connection(IConnPool connPool,String name){
		this.connPool=connPool;
		this.name=name;
	}
	@Override
	public void close() {
		this.connPool.releaseConn(this);
	}
	@Override
	public void destroy() {
		System.out.println("destroy connection---"+name);
	}
	
	@Override
	public String toString() {
		// TODO Auto-generated method stub
		super.toString();
		return name;
	}

}

public interface IConnPool {
	 /**
	  * 获得一个可用连接，超过最大连接数时线程等待，直到有有连接释放时返回一个可用连接或者超时返回null 
	  * @param maxWaitTime
	  * @return
	  */
	public IConnection getConn();
	/**
	 * 将释放的空闲连接加入空闲连接池
	 * @param conn
	 */
	public void releaseConn(IConnection conn);
	/**
	 * 销毁连接池
	 */
	public void destroy();
	/**
	 * 获取当前线程对应的连接
	 * @return
	 */
	public IConnection getCurrentConn();
}

import java.util.ArrayList;
import java.util.List;
import java.util.UUID;

public class ConnPool implements IConnPool {
	private int initNum;
	private int maxNum;
	private int hasAlready;
	private long maxWaitTime;
	private final List<IConnection> freeConnList;
	private final List<IConnection> activeConnList;
	private static ThreadLocal<IConnection> threadLocalVar=new ThreadLocal<IConnection>(){
		protected IConnection initialValue() {
			return null;
		};
	};
	public ConnPool(){
		this.initNum=3;
		this.maxNum=5;
		this.hasAlready=0;
		this.maxWaitTime=1000;
		this.freeConnList=new ArrayList<IConnection>(maxNum);
		this.activeConnList=new ArrayList<IConnection>(maxNum);
		init();
	}
	public ConnPool(int initNum,int maxNum,long maxWaitTime){
		this.initNum=initNum;
		this.maxNum=maxNum;
		this.hasAlready=0;
		this.maxWaitTime=maxWaitTime;
		this.freeConnList=new ArrayList<IConnection>(maxNum);
		this.activeConnList=new ArrayList<IConnection>(maxNum);
		init();
	}
	private void init(){
		for(int i=0;i<this.initNum;i++){
			synchronized (this) {
				this.freeConnList.add(new Connection(this,UUID.randomUUID().toString()));
				hasAlready++;
			}
		}
	}
	@Override
	public synchronized IConnection getConn()  {
			IConnection conn=null;
			if(!this.freeConnList.isEmpty()){
				conn=this.freeConnList.remove(0);
				if(conn!=null)
					threadLocalVar.set(conn);//为线程绑定连接
				this.activeConnList.add(conn);
				return conn;
			}
			if(hasAlready<maxNum){
				conn = new Connection(this,UUID.randomUUID().toString());
				hasAlready++;
				if(conn!=null)
					threadLocalVar.set(conn);//为线程绑定连接
				this.activeConnList.add(conn);
				return conn;
			}
			try {
				this.wait(maxWaitTime);
				if(!this.freeConnList.isEmpty()){
					conn=this.freeConnList.remove(0);
					if(conn!=null)
						threadLocalVar.set(conn);//为线程绑定连接
					this.activeConnList.add(conn);
					return conn;
				}
				return null;
			} catch (InterruptedException e) {
				e.printStackTrace();
				return null;
			}
	}
	@Override
	public synchronized void releaseConn(IConnection conn) {
		if(this.activeConnList.contains(conn)){
			this.freeConnList.add(conn);
			this.activeConnList.remove(conn);
			threadLocalVar.remove();
			this.notify();
                 }
	}
	@Override
	public synchronized void destroy() {
		IConnection conn=null;
		int temp=this.freeConnList.size();
		for(int i=0;i<temp;i++){
			conn=this.freeConnList.remove(0);
			conn.destroy();
		}
		temp=this.activeConnList.size();
		for(int i=0;i<temp;i++){
			conn=this.activeConnList.remove(0);
			conn.destroy();
		}
		conn=null;
		this.hasAlready=0;
	}
         @Override
	public IConnection getCurrentConn() {
		return threadLocalVar.get();
	}
	
}

package com.xyz.connpool;

import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
public class ConnPoolManager {
	private int initConnNum;
	private int maxConnNum;
	private long maxWaitTime;
	// 连接池存放
	public Map<Integer,IConnPool> pools=new ConcurrentHashMap<Integer, IConnPool>();
//	public Hashtable<Integer,IConnPool> pools = new Hashtable<Integer, IConnPool>();
	
	public ConnPoolManager(int initConnNum,int maxConnNum, long maxWaitTime){
		this.initConnNum=initConnNum;
		this.maxConnNum=maxConnNum;
		this.maxWaitTime=maxWaitTime;
		init();
	}
	
	// 初始化所有的连接池
	private void init(){
		for(int hostId =0;hostId<3;hostId++){
			ConnPool connPool=new ConnPool(this.initConnNum,this.maxConnNum, this.maxWaitTime);
			if(connPool != null){
				pools.put(hostId,connPool);
				System.out.println("Info:Init connPool successed for hostId ->" +hostId);
			}
		}
	}
	
	/**
	 * 根据主机id获取连接池
	 * @param hostId
	 * @return
	 */
	public IConnPool getPool(int hostId){
		IConnPool pool = null;
		if(pools.containsKey(hostId)){
			 pool = pools.get(hostId);
		}
		return pool;
	}
	
	/**
	 * 获取一个到主机hostId的连接
	 * @param hostId
	 * @return
	 */
	public IConnection getConn(int hostId){
		IConnPool connPool = getPool(hostId);
		if(connPool==null){
			System.out.println("Error:Can't find this connecion pool for hostId->"+hostId);
			return null;
		}
		return connPool.getConn();
	}
	
	/**
	 * 关闭指定主机的某个链接
	 * @param hostId
	 * @param conn
	 */
	public void close(int hostId,IConnection conn){
			IConnPool pool = getPool(hostId);
			if(pool != null)
				pool.releaseConn(conn);
	}
	/**
	 * 注销某个主机的连接池
	 * @param poolName
	 */
	public void destroy(int hostId){
		IConnPool pool = getPool(hostId);
		if(pool != null){
			pool.destroy();
		}
		pools.remove(pool);
	}
	/**
	 * 注销所有连接池
	 */
	public void destory(){
		for(int hostId:pools.keySet()){
			this.destroy(hostId);
		}
	}
}

package com.xyz.connpool;
import java.util.concurrent.CountDownLatch;

public class Demo {
	public final static int REQUESTNUM=200;
	public final static int DURATION=20;
	 
	public static void main(String [] args) throws Exception{
		final CountDownLatch startGate=new CountDownLatch(1);
		final CountDownLatch endGate=new CountDownLatch(REQUESTNUM);
		
		final ConnPoolManager cpm=new ConnPoolManager(5, 10, 1000);
		final IConnection conns[] =new IConnection[REQUESTNUM];
		for(int i=0;i<REQUESTNUM;i++){
			final int flag=i;
			new Thread(new Runnable() {
				@Override
				public void run() {
					try {
						startGate.await();
					} catch (InterruptedException e1) {}
					
					conns[flag]=cpm.getConn(0);
					System.out.println(conns[flag]);
					try {
						Thread.sleep(DURATION);
					} catch (InterruptedException e) {}
					cpm.close(0, conns[flag]);
					
					endGate.countDown();
				}
			}).start();
		}

		long begin = System.currentTimeMillis();
		startGate.countDown();
		endGate.await();
		long over = System.currentTimeMillis();
		System.out.println(over-begin);
//	    Thread.sleep(5000);
	    cpm.destory();
	}
}

源代码下载https://github.com/ZhenShiErGe/ConnectionPool.git