Java如何建立多執行緒伺服器？

在Java程式設計中，如何建立多執行緒伺服器？

以下範例演示如何使用ServerSocket類的MultiThreadServer(socketname)方法和Socket類的ssock.accept()方法來建立多執行緒伺服器。

package com.yiibai;

import java.io.IOException;
import java.io.PrintStream;
import java.net.ServerSocket;
import java.net.Socket;

public class MultiThreadServer implements Runnable {
   Socket csocket;
   MultiThreadServer(Socket csocket) {
      this.csocket = csocket;
   }
   public static void main(String args[]) throws Exception { 
      ServerSocket ssock = new ServerSocket(8806);
      System.out.println("Server Start and Listening: ");

      while (true) {
         Socket sock = ssock.accept();
         System.out.println("Connected");
         new Thread(new MultiThreadServer(sock)).start();
      }
   }
   public void run() {
      try {
         PrintStream pstream = new PrintStream(csocket.getOutputStream());
         for (int i = 100; i >= 0; i--) {
            pstream.println(i + " bottles of beer on the wall");
         }
         pstream.close();
         csocket.close();
      } catch (IOException e) {
         System.out.println(e);
      }
   }
}

上述程式碼範例將產生以下結果 -

Server Start and Listening:

範例-2

以下是如何建立多執行緒伺服器的另一個範例。

package com.yiibai;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;

import java.net.ServerSocket;
import java.net.Socket;
import java.text.SimpleDateFormat;
import java.util.Calendar;

public class MultiThreadServer2 {
    ServerSocket myServerSocket;
    boolean ServerOn = true;

    public MultiThreadServer2() { 
      try {
         myServerSocket = new ServerSocket(12345);
      } catch(IOException ioe) { 
         System.out.println("Could not create server socket on port 12345. Quitting.");
         System.exit(-1);
      } 

      Calendar now = Calendar.getInstance();
      SimpleDateFormat formatter = new SimpleDateFormat(
         "yyyy/MM/dd \'at\' hh:mm:ss ");
      System.out.println("It is now : " + formatter.format(now.getTime()));

      while(ServerOn) { 
         try { 
            Socket clientSocket = myServerSocket.accept();
            ClientServiceThread cliThread = new ClientServiceThread(clientSocket);
            cliThread.start(); 
         } catch(IOException ioe) { 
            System.out.println("Exception found on accept. Ignoring. Stack Trace :"); 
            ioe.printStackTrace(); 
         }  
      } 
      try { 
         myServerSocket.close(); 
         System.out.println("Server Stopped"); 
      } catch(Exception ioe) { 
         System.out.println("Error Found stopping server socket"); 
         System.exit(-1); 
      } 
   }

    public static void main(String[] args) {
        new MultiThreadServer2();
    }

    class ClientServiceThread extends Thread {
        Socket myClientSocket;
        boolean m_bRunThread = true;

        public ClientServiceThread() {
            super();
        }

        ClientServiceThread(Socket s) {
            myClientSocket = s;
        }

        public void run() {
            BufferedReader in = null;
            PrintWriter out = null;
            System.out.println("Accepted Client Address - " + myClientSocket.getInetAddress().getHostName());
            try {
                in = new BufferedReader(new InputStreamReader(myClientSocket.getInputStream()));
                out = new PrintWriter(new OutputStreamWriter(myClientSocket.getOutputStream()));

                while (m_bRunThread) {
                    String clientCommand = in.readLine();
                    System.out.println("Client Says :" + clientCommand);

                    if (!ServerOn) {
                        System.out.print("Server has already stopped");
                        out.println("Server has already stopped");
                        out.flush();
                        m_bRunThread = false;
                    }
                    if (clientCommand.equalsIgnoreCase("quit")) {
                        m_bRunThread = false;
                        System.out.print("Stopping client thread for client : ");
                    } else if (clientCommand.equalsIgnoreCase("end")) {
                        m_bRunThread = false;
                        System.out.print("Stopping client thread for client : ");
                        ServerOn = false;
                    } else {
                        out.println("Server Says : " + clientCommand);
                        out.flush();
                    }
                }
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                try {
                    in.close();
                    out.close();
                    myClientSocket.close();
                    System.out.println("...Stopped");
                } catch (IOException ioe) {
                    ioe.printStackTrace();
                }
            }
        }
    }
}

上述程式碼範例將產生以下結果 -

It is now : 2017/09/20 at 10:45:19

package com.yiibai;

import java.io.IOException;
import java.net.InetAddress;
import java.net.Socket;
import java.net.SocketException;
import java.net.UnknownHostException;

public class SocketClient {
    public static void main(String[] args) {
        try {
            //InetAddress addr = InetAddress.getByName("127.0.0.1");
            Socket theSocket = new Socket("127.0.0.1", 12345);
            System.out.println("Connected to " + theSocket.getInetAddress() + " on port " + theSocket.getPort()
                    + " from port " + theSocket.getLocalPort() + " of " + theSocket.getLocalAddress());
        } catch (UnknownHostException e) {
            System.err.println("I can't find " + e);
        } catch (SocketException e) {
            System.err.println("Could not connect to " + e);
        } catch (IOException e) {
            System.err.println(e);
        }
    }
}