线程池

最新推荐文章于 2025-07-22 08:12:47 发布

iteye_1458

最新推荐文章于 2025-07-22 08:12:47 发布

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分类专栏： Thread 文章标签： Java Socket 工作 JDK .net

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[size=medium][b]为什么使用线程池?[/b][/size]
[size=medium]为了减少瞬间峰值问题，服务器一般都使用线程池，规定了同时并发的最大数量，避免了线程的无限增长.[/size]

在浏览器里输出 http://127.0.0.1:8888/
就可以出结果了

[size=medium]Main.java[/size]


package com.apq.threadpool;

import com.apq.server.MiniServer;

public class Main {

	public static void main(String[] args) {
		new EchoServer(8888, 1000).service();
	}
}

[size=medium]EchoServer.java[/size]


package com.apq.threadpool;

import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class EchoServer {
	//监听的端口号
	private final int port;

	//单个cpu工作线程数量
	private final int poolSize;

	private ServerSocket serverSocket;

	//线程池
	private ThreadPool threadPool;

	//jdk线程池
	private ExecutorService executorService;

	public EchoServer(int port, int poolSize) {
		this.port = port;
		this.poolSize = poolSize;
		//this.threadPool = new ThreadPool(Runtime.getRuntime().availableProcessors() * poolSize);
		this.executorService = Executors.newFixedThreadPool(Runtime.getRuntime().availableProcessors() * poolSize);
	}

	//负责为每个客户分配一个线程
	public void service() {
		try {
			serverSocket = new ServerSocket(port);
			echo("Listening on " + serverSocket);
			while(true) {
				echo("Accepting...");
				Socket clientSocket = serverSocket.accept();
				echo("Connected to " + clientSocket);
				//创建一个工作线程并启动(没有线程池的)
				//new Thread(new Handler(clientSocket)).start();

				//由线程池来处理客户通信
				//this.threadPool.putHandler(new Handler(clientSocket));

				//用jdk自带的线程池来处理客户通信
				this.executorService.execute(new Handler(clientSocket));
			}
		} catch (IOException e) {
			System.err.println(e);
		}
	}

	private void echo(String msg) {
		System.out.println(msg);
	}
}

[size=medium]ThreadPool.java[/size]


package com.apq.threadpool;

import java.util.*;

public class ThreadPool extends ThreadGroup {
	private static final int MAX_HANDLER = 100;
	// 线程数量
	private int poolSize;

	// 工作队列
	private static LinkedList<Runnable> workQueue;

	// 线程池ID
	private static int threadPoolID;

	// 工作线程ID
	private int workThreadPoolID;

	private int count;

	// 构造函数
	public ThreadPool(int poolSize) {
		super("ThreadPool-" + (threadPoolID++));
		this.poolSize = poolSize;
		this.count = 0;
		workQueue = new LinkedList<Runnable>();
		startWorks();
		System.out.println("The EchoServer has started.");
	}

	// 创建并启动工作线程
	private void startWorks() {
		for (int i = 0; i < this.poolSize; i++) {
			new WorkThread().start();
		}
	}

	// 向工作队列加入一个新任务,由工作线程执行该任务
	public synchronized void putHandler(Runnable handler) {
		while (count >= MAX_HANDLER) {
			try {
				wait();
			} catch (InterruptedException e) {
			}
		}
		workQueue.add(handler);
		count++;
		notifyAll();
	}

	// 从工作队列中取出一个任务,工作线程会调用此方法
	public synchronized Runnable getHandler() {
		while (count <= 0) {
			try {
				wait();
			} catch (InterruptedException e) {
			}
		}
		Runnable handler = workQueue.removeFirst();
		count--;
		notifyAll();
		return handler;
	}

	// 内部类 工作线程
	private class WorkThread extends Thread {
		public WorkThread() {
		}

		@Override
		public void run() {
			while (!isInterrupted()) {
				Runnable handler = getHandler();
				if (handler != null)
					handler.run();
			}
		}
	}
}

[size=medium]Handler.java[/size]


package com.apq.threadpool;

import java.io.DataOutputStream;
import java.io.IOException;
import java.net.Socket;

//负责与单个客户的通信
public class Handler implements Runnable {
	private Socket clientSocket;

	public Handler(Socket clientSocket) {
		this.clientSocket = clientSocket;
	}

	@Override
	public void run() {
		try {
			DataOutputStream out = new DataOutputStream(clientSocket
					.getOutputStream());
			out.writeBytes("HTTP/1.1 200 OK\r\n");
			out.writeBytes("Content-type: text/html\r\n");
			out.writeBytes("\r\n");

			out.writeBytes("<html><head></head><body>");
			out.writeBytes("<p>" + "new connection accepted!<br>"
					+ clientSocket.getInetAddress() + ":"
					+ clientSocket.getPort() + "</p>");
			out.writeBytes("</body></html>");
		} catch (IOException e) {
			//record log
		} finally {
			if (clientSocket != null)
				try {
					clientSocket.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
		}

	}

}