学步园

转自：http://www.cnblogs.com/harrisonpc/archive/2011/03/31/2001565.html

 Socket通常也称做”套接字“，用于描述IP地址和端口，废话不多说，它就是网络通信过程中端点的抽象表示。值得一提的是，Java在包java.net中提供了两个类Socket和ServerSocket，分别用来表示双向连接的客户端和服务端。这是两个封装得非常好的类，使用起来很方便！

    下面将首先创建一个SocketServer的类作为服务端如下，该服务端实现了多线程机制，可以在特定端口处监听多个客户请求，一旦有客户请求，Server总是会创建一个服务纯种来服务新来的客户，而自己继续监听。程序中accept()是一个阻塞函数，所谓阻塞性方法就是说该方法被调用后将等待客户的请求，直到有一个客户启动并请求连接到相同的端口，然后accept()返回一个对应于客户的Socket。这时，客户方和服务方都建立了用于通信的Socket，接下来就是由各个Socket分别打开各自的输入、输出流。

• SocketServer类，服务器实现：

package learn.test;

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

public class SocketServer {

	ServerSocket sever;

	public SocketServer(int port) {
		try {
			sever = new ServerSocket(port);
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	public void beginListen() {
		while (true) {
			try {
				final Socket socket = sever.accept();

				new Thread(new Runnable() {
					public void run() {
						BufferedReader in;
						try {
							in = new BufferedReader(new InputStreamReader(
									socket.getInputStream(), "UTF-8"));
							PrintWriter out = new PrintWriter(
									socket.getOutputStream());
							while (!socket.isClosed()) {
								String str;
								str = in.readLine();
								out.println("Hello!world!! " + str);
								out.flush();
								if (str == null || str.equals("end"))
									break;
								System.out.println(str);
							}
							socket.close();
						} catch (IOException e) {
							e.printStackTrace();
						}
					}
				}).start();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}
}

SocketClient类，客户端实现：

public class SocketClient {
	static Socket client;

	public SocketClient(String site, int port) {
		try {
			client = new Socket(site, port);
			System.out.println("Client is created! site:" + site + " port:"
					+ port);
		} catch (UnknownHostException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	public String sendMsg(String msg) {
		try {
			BufferedReader in = new BufferedReader(new InputStreamReader(
					client.getInputStream()));
			PrintWriter out = new PrintWriter(client.getOutputStream());
			out.println(msg);
			out.flush();
			return in.readLine();
		} catch (IOException e) {
			e.printStackTrace();
		}
		return "";
	}

	public void closeSocket() {
		try {
			client.close();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	public static void main(String[] args) throws Exception {

	}
}

 接下来就是来测试Socket通信了！

   先运行TestSocketServer类，打开服务端，在12345端口处监听！

public class TestSocketServer {
	public static void main(String[] argvs) {
		SocketServer server = new SocketServer(12345);
		server.beginListen();
	}
}

再运行TestSocketClient类：

public class TestSocketClient {
	public static void main(String[] args) {

		SocketClient client = new SocketClient("127.0.0.1", 12345);
		System.out.println(client.sendMsg("nimei1"));
		client.closeSocket();

		SocketClient client1 = new SocketClient("127.0.0.1", 12345);
		System.out.println(client1.sendMsg("nimei1111"));
		client1.closeSocket();

		SocketClient client11 = new SocketClient("127.0.0.1", 12345);
		System.out.println(client11.sendMsg("nimei11111111"));
		client11.closeSocket();

		SocketClient client111 = new SocketClient("127.0.0.1", 12345);
		System.out.println(client111.sendMsg("nimei11111111111111111"));
		client111.closeSocket();

	}
}

输出结果如下：

服务端：

Client is created! site:127.0.0.1 port:12345
Hello!world!! nimei1
Client is created! site:127.0.0.1 port:12345
Hello!world!! nimei1111
Client is created! site:127.0.0.1 port:12345
Hello!world!! nimei11111111
Client is created! site:127.0.0.1 port:12345
Hello!world!! nimei11111111111111111

客户端：

nimei1
nimei1111
nimei11111111
nimei11111111111111111