Java基础--网络编程1

使用socket连接到服务器

public static void main(String[] args) throws IOException {
		Socket s = new Socket("time-A.timefreq.bldrdoc.gov", 13); // 构建一个套接字，链接给定主机和端口
		s.setSoTimeout(10000); // 设置超时时间10s
		InputStream inStream = s.getInputStream();
		Scanner in = new Scanner(inStream);
		while (in.hasNext()) {
			String line = in.nextLine();
			System.out.println(line); // 57196 15-06-23 13:16:02 50 1 0 43.7
										// UTC(NIST) *
		}
		in.close();
		s.close();
		/*
		 * 使用上述超时设置，socket会一直阻塞，直到达到主机的初始链接
		 * 
		 * 可以先构建一个无连接的套接字，然后在设置一个超时来进行链接
		 * 
		 * InetAddress:主机名和因特网地址之间转换
		 */
		Socket s2 = new Socket();
		s2.connect(new InetSocketAddress("time-A.timefreq.bldrdoc.gov", 13),
				10000);
		s2.close();
		InetAddress address = InetAddress
				.getByName("time-A.timefreq.bldrdoc.gov");
		System.out.println(address.toString()); // time-A.timefreq.bldrdoc.gov/132.163.4.101
		byte[] addressBytes = address.getAddress();
		for (byte b : addressBytes) {
			System.out.print(b + ":"); // -124:-93:4:101:
		}
		System.out.println();
		System.out.println("===============");
		String host = "132.163.4.101";
		if (!host.equals("")) {
			InetAddress[] addresses = InetAddress.getAllByName(host);
			for (InetAddress a : addresses) {
				System.out.println(a);
			}
		} else {
			InetAddress localHostAddress = InetAddress.getLocalHost();
			System.out.println(localHostAddress);
		}
	}

实现服务器

1.简单的处理单连接的服务器

public static void main(String[] args) throws IOException {
		ServerSocket s = new ServerSocket(8189); // 建立一个监听8189端口的服务器
		Socket incoming = s.accept(); // 服务器等待客户端连接
		InputStream in = incoming.getInputStream();
		OutputStream out = incoming.getOutputStream();
		Scanner console = new Scanner(in);
		PrintWriter pw = new PrintWriter(out, true);
		pw.println("Hello! Enter BYE to exit"); // 向客户端发出信息
		boolean done = false;
		// 等待客户端输入
		while (!done && console.hasNext()) {
			String line = console.nextLine();
			pw.println(line);
			if (line.trim().equals("BYE")) {
				done = true;
			}
		}
		console.close();
		s.close();
	}

2.可以处理多连接的服务器

public class ThreadEchoServer {

	public static void main(String[] args) throws IOException {
		int i = 1;
		ServerSocket server = new ServerSocket(8189);
		boolean done = false;
		while (!done) {
			Socket socket = server.accept();
			System.out.println("Spwwning " + i);
			Runnable threadSocket = new ThreadSocket(socket);
			Thread thread = new Thread(threadSocket);
			thread.start();
			i++;
			if (i > 4) {
				done = true;
			}
		}
		System.out.println("超过最大连接数");
		server.close();
	}
}

class ThreadSocket implements Runnable {
	private Socket socket;

	public ThreadSocket(Socket socket) {
		this.socket = socket;
	}

	@Override
	public void run() {
		try {
			InputStream is = socket.getInputStream();
			OutputStream os = socket.getOutputStream();
			PrintWriter pw = new PrintWriter(os, true);
			pw.println("Hello, Welcome to my server....");
			Scanner console = new Scanner(is);
			boolean done = false;
			while (!done && console.hasNext()) {
				String line = console.nextLine();
				pw.println("Server response: " + line);
				if (line.trim().equals("BYE")) {
					done = true;
				}
			}
			console.close();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}

半关闭（half-close）

功能：套接字连接的一端可以终止其输出，同时仍然可以接收另一端的数据

Socket socket = new Socket(host, port);
		Scanner console = new Scanner(socket.getInputStream());
		PrintWriter pw = new PrintWriter(socket.getOutputStream());
		pw.print("....");
		pw.flush();
		socket.shutdownOutput();
		// 关闭输出流，此时处于半连接状态
		while (console.hasNext()) {
			String line = console.nextLine();
		}
		socket.close();