使用Jakarta Commons Pool可以根据需要快速的实现自己的对象池,只需要实现或者KeyedPoolableObjectFactory接口。KeyedPoolableObjectFactory和的不同之处在于KeyedPoolableObjectFactory的每个方法都比多了一个Object key的参数,使用这个参数可以使得对象池中的每个对象都有所不同。
定义了五个方法(摘至Jakarta Commons Pool API文档):
- is called whenever a new instance is needed.
- is invoked on every instance before it is returned from the pool.
- is invoked on every instance when it is returned to the pool.
- is invoked on every instance when it is being "dropped" from the pool (whether due to the response from , or for reasons specific to the pool implementation.)
- is invoked in an implementation-specific fashion to determine if an instance is still valid to be returned by the pool. It will only be invoked on an instance.
下面是我的一个SocketChannel对象池的实现,实现了KeyedPoolableObjectFactory接口。
我的测试程序:
package sample.pool;
import java.io.IOException;
import java.net.*;
import java.nio.ByteBuffer;
import java.nio.channels.*;
import java.util.*;
import org.apache.commons.pool.*;
import org.apache.commons.pool.impl.*;
/**//**
* Title: 测试的线程类
*
* Description:
*
* Copyright: Copyright (c) 2005
*
* Company:
*
* @author George Hill
* @version 1.0
*/
public class TestThread implements Runnable {
// 线程名称
private String name;
// 对象池
private KeyedObjectPool pool;
// 连接的网络地址
private InetSocketAddress address;
public TestThread(String name, KeyedObjectPool pool,
InetSocketAddress address) {
this.name = name;
this.pool = pool;
this.address = address;
}
public void run() {
System.out.println(name + ": Client Start");
SocketChannel channel = null;
try {
channel = (SocketChannel) pool.borrowObject(address);
}
catch (Exception ex) {
ex.printStackTrace();
}
// 从对象池中借出对象成功
if (channel != null) {
System.out.println(name + ": Borrow Channel successfully!");
try {
channel.configureBlocking(false);
// 创建Selector
Selector selector = Selector.open();
// 向Selector注册我们需要的READ事件
SelectionKey skey = channel.register(selector, SelectionKey.OP_READ);
boolean stop = false;
int n = 0;
int read = 0;
ByteBuffer buffer = ByteBuffer.allocate(1024);
System.out.println("Client Start");
// 轮询
while (!stop) {
// 获取Selector返回的时间值
n = selector.select();
// 当传回的值大于0事,读事件发生了
if (n > 0) {
Set set = selector.selectedKeys();
Iterator it = set.iterator();
while (it.hasNext()) {
skey = (SelectionKey) it.next();
it.remove();
if (skey.isReadable()) {
SocketChannel sc = (SocketChannel) skey.channel();
while ( (read = sc.read(buffer)) != -1) {
if (read == 0) {
break;
}
buffer.flip();
byte[] array = new byte[read];
buffer.get(array);
String s = new String(array);
System.out.print(s);
buffer.clear();
if (s.indexOf("new") != -1) {
stop = true;
System.out.println();
}
}
}
}
}
}
}
catch (IOException ioe) {
ioe.printStackTrace();
}
try {
pool.returnObject(address, channel);
}
catch (Exception ex) {
ex.printStackTrace();
}
}
System.out.println(name + ": Client Stop");
}
/**//**
* 测试方法
* @param args String[] 控制台参数
* @throws Exception
*/
public static void main(String[] args) throws Exception {
SocketPoolableObjectFactory factory = new SocketPoolableObjectFactory();
StackKeyedObjectPoolFactory poolFactory = new StackKeyedObjectPoolFactory(factory);
KeyedObjectPool pool = poolFactory.createPool();
// 创建连接清华BBS的线程
Thread t1 = new Thread(new TestThread("清华", pool, new InetSocketAddress("bbs.tsinghua.edu.cn", 23)));
t1.start();
// 创建连接华南理工BBS的线程
Thread t2 = new Thread(new TestThread("华南理工", pool, new InetSocketAddress("bbs.gznet.edu.cn", 23)));
t2.start();
}
}
参考资料:
1. Jakarta Commons Pool网站:
2. IBM开发者的一篇很好的文章
《使用Jakarta Commons Pool处理对象池化》
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