Java Socket学习---多线程阻塞_JAVA_编程开发_程序员俱乐部

上篇?Java Socket学习---单线程阻塞?

这次文章中，是在上篇的基础上，在服务端使用了多线程的方式来管理连接，主线程负责接收连接，在接到连接后变创建新的线程，每个线程负责与自己的客户端进行通信。

与单线程阻塞的例子相比来说，服务端可以与多个客户端进行通信了，不过多线程频繁的创建与销毁便会带来很大的资源开销，而系统的网络资源等都是有限的；因此便可以引入线程池，可以在某种程度上重用线程，减少线程的创建和销毁的次数以减少开销。

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下例代码中包含了使用和不使用线程池（针对Server端）的两种方式，如果测试的时候，解开注释的代码即可以。

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Server端代码：

class="java">package com.henushang.socket.chapter2;

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

import com.henushang.socket.util.SocketUtils;

public class EchoServer {

	private int port = 8000;
	private ServerSocket serverSocket;
	private ExecutorService executorService ; // 连接池
	private final int POOL_SIZE = 4;// 连接池大小
	
	public EchoServer() throws Exception{
		serverSocket = new ServerSocket(port);
		executorService = Executors.newFixedThreadPool(Runtime.getRuntime().availableProcessors() * POOL_SIZE);
		System.out.println("waitting connet...");
	}
	
	/**
	 * 接受连接
	 * 
	 * @author henushang
	 */
	public void service() {
		Socket socket = null;
		while (true) {
			try {
				socket = serverSocket.accept();
				executorService.execute(new Handler(socket));// 使用连接池
//				new Thread(new Handler(socket)).start();// 不使用连接池
			} catch (IOException e) {
				e.printStackTrace();
			}
			
		}
	}
	
	public static void main(String[] args) throws Exception {
		new EchoServer().service();
	}
	
	/**
	 * 线程类，负责维持与一个客户端的通信 
	 *
	 * @author henushang
	 */
	class Handler implements Runnable{
		private Socket socket = null;
		
		public Handler(Socket socket) {
			this.socket = socket;
		}
		@Override
		public void run() {
			System.out.println("new connection accepted:" + socket.getInetAddress() + ":" + socket.getPort());
			try {
				BufferedReader reader = SocketUtils.getReader(this.socket);
				PrintWriter writer = SocketUtils.getWriter(this.socket);
				String msg = null;
				while ((msg = reader.readLine()) != null) {
					System.out.println(msg);
					// 因为客户端接收消息的时候使用的是readline()方法，如果消息没有以\r\n 结尾的话，客户端则接收不到消息
//					writer.write(SocketUtils.echo(msg) + "\r\n");
					writer.println(SocketUtils.echo(msg));
					writer.flush();
					if ("bye".equals(msg)) {
						break;
					}
				}
			} catch (IOException e) {
				e.printStackTrace();
			} finally{
				SocketUtils.close(socket);
			}
		}
	}
}

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Client端代码（与上次代码一样）：

package com.henushang.socket;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;

import com.henushang.socket.util.SocketUtils;

public class EchoClient {
	private String host = "127.0.0.1";
	private int port = 8000;
	private Socket socket ;
	
	public EchoClient() throws Exception {
		socket = new Socket(host, port);
	}
	
	public void talk() throws IOException {
		try {
			BufferedReader reader = SocketUtils.getReader(socket);
			PrintWriter writer = SocketUtils.getWriter(socket);
			// 读取本地控制台的消息
			BufferedReader localReader = new BufferedReader(new InputStreamReader(System.in));
			String msg = null;
			while ((msg = localReader.readLine()) != null) {
				writer.println(msg);
				writer.flush();
				System.out.println(reader.readLine());
				if ("bye".equals(msg)) {
					break;
				}
			}
		} catch (Exception e) {
			e.printStackTrace();
		}finally {
			SocketUtils.close(socket);
		}
	}
	
	public static void main(String[] args) throws Exception{
		new EchoClient().talk();
	}
}

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SocketUtils代码：

package com.henushang.socket.util;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.Socket;
import java.nio.channels.SocketChannel;

public class SocketUtils {
	
	public static PrintWriter getWriter(Socket socket) throws IOException {
		OutputStream os = socket.getOutputStream();
		return new PrintWriter(os);
	}
	
	public static PrintWriter getWriter(SocketChannel socketChannel) throws IOException {
		return getWriter(socketChannel.socket());
	}
	
	public static BufferedReader getReader(Socket socket) throws IOException{
		InputStream is = socket.getInputStream();
		return new BufferedReader(new InputStreamReader(is, "UTF-8"));
	}
	
	public static BufferedReader getReader(SocketChannel socketChannel) throws IOException{
		return getReader(socketChannel.socket());
	}
	
	public static void close(Socket socket) {
		try {
			if (socket != null) {
				socket.close();
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	public static void close(SocketChannel socketChannel) {
		try {
			if (socketChannel != null) {
				socketChannel.close();
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
	
	public static String echo(String msg) {
		return "echo:" + msg;
	}
}

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• 示例代码.zip (2.3 KB)
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