套接字编程多个客户端到一个服务器 [英] socket programming multiple client to one server

问题描述

如何处理多个客户端连接到一台服务器?我有这个 LogServer.java

How do you handle multiple client to connect to one server? I have this LogServer.java

import javax.net.ssl.*;
import javax.net.*;
import java.io.*;
import java.net.*;

public class LogServer {
  private static final int PORT_NUM = 5000;
  public static void main(String args[]) {
    ServerSocketFactory serverSocketFactory =
      ServerSocketFactory.getDefault();
    ServerSocket serverSocket = null;
    try {
      serverSocket =
        serverSocketFactory.createServerSocket(PORT_NUM);
    } catch (IOException ignored) {
      System.err.println("Unable to create server");
      System.exit(-1);
    }
    System.out.printf("LogServer running on port: %s%n", PORT_NUM);
    while (true) {
      Socket socket = null;
      try {
        socket = serverSocket.accept();
        InputStream is = socket.getInputStream();
        BufferedReader br = new BufferedReader(
          new InputStreamReader(is, "US-ASCII"));
        String line = null;
        while ((line = br.readLine()) != null) {
          System.out.println(line);
        }
      } catch (IOException exception) {
        // Just handle next request.
      } finally {
        if (socket != null) {
          try {
            socket.close();
          } catch (IOException ignored) {
          }
        }
      }
    }
  }
}

和一个带有像这样的部分代码的嵌入式小程序，例如

and an embedded applet with part of the code like this e.g

import java.io.*;
import java.util.logging.*;

public class LogTest
{
  private static Logger logger = Logger.getAnonymousLogger();

  public static void main(String argv[]) throws IOException
  {
    Handler handler = new SocketHandler("localhost", 5000);
    logger.addHandler(handler);
    logger.log(Level.SEVERE, "Hello, World");
    logger.log(Level.SEVERE, "Welcome Home");
    logger.log(Level.SEVERE, "Hello, World");
    logger.log(Level.SEVERE, "Welcome Home");
  }
}

现在的问题是，如果我在服务器上运行java LogServer"，它将打开应用程序并等待输入流，如果我打开我的站点，它将开始流式传输日志.但是，如果我使用其他计算机/网络再打开一个，则第二个站点不会记录流.似乎是因为第一个仍然绑定到端口 5000.

now the question is if I run "java LogServer" on the server, it will open the application and waiting for input stream and if I open my site, it will start streaming the log. But if I open one more using other computer/network, the second site does not log the stream. seems like it's because the first one still bind to port 5000.

我该如何处理?套接字实际上如何与多个客户端/一个服务器一起工作?

How do I handle this? How does socket actually work with multiple client / one server?

推荐答案

对于每个客户端，您需要启动单独的线程.示例:

For every client you need to start separate thread. Example:

public class ThreadedEchoServer {

    static final int PORT = 1978;

    public static void main(String args[]) {
        ServerSocket serverSocket = null;
        Socket socket = null;

        try {
            serverSocket = new ServerSocket(PORT);
        } catch (IOException e) {
            e.printStackTrace();

        }
        while (true) {
            try {
                socket = serverSocket.accept();
            } catch (IOException e) {
                System.out.println("I/O error: " + e);
            }
            // new thread for a client
            new EchoThread(socket).start();
        }
    }
}

和

public class EchoThread extends Thread {
    protected Socket socket;

    public EchoThread(Socket clientSocket) {
        this.socket = clientSocket;
    }

    public void run() {
        InputStream inp = null;
        BufferedReader brinp = null;
        DataOutputStream out = null;
        try {
            inp = socket.getInputStream();
            brinp = new BufferedReader(new InputStreamReader(inp));
            out = new DataOutputStream(socket.getOutputStream());
        } catch (IOException e) {
            return;
        }
        String line;
        while (true) {
            try {
                line = brinp.readLine();
                if ((line == null) || line.equalsIgnoreCase("QUIT")) {
                    socket.close();
                    return;
                } else {
                    out.writeBytes(line + "

");
                    out.flush();
                }
            } catch (IOException e) {
                e.printStackTrace();
                return;
            }
        }
    }
}

您还可以使用更高级的解决方案，即使用 NIO 选择器，因此您不必为每个客户端创建线程，但这有点复杂.

You can also go with more advanced solution, that uses NIO selectors, so you will not have to create thread for every client, but that's a bit more complicated.

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