/* 聊天程序之服務器端ChatServer.java
 * 建立服務器端，接收客戶端連接，
 * 發送信息、關閉連接
*/


import java.io.*;
import java.net.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class ChatServer extends JFrame {
   private JTextField inputBox;
   private JTextArea outFrame;
   private ObjectOutputStream outputS;
   private ObjectInputStream inputS;
   private ServerSocket toserver;
   private Socket connection;
   private int counter = 1;

   public ChatServer()
   {
      super( "Server" );

      Container container = getContentPane();

      inputBox = new JTextField();
      inputBox.setEnabled( false );
      //輸出
      inputBox.addActionListener(
      //監聽
         new ActionListener() {

            // 發送信息
            public void actionPerformed( ActionEvent event )
            {
               sendMsg( event.getActionCommand() );
            }
         }
      );

      container.add( inputBox, BorderLayout.NORTH );

      // 輸出框
      outFrame = new JTextArea();
      container.add( new JScrollPane( outFrame ),
         BorderLayout.CENTER );

      setSize( 280, 160 );
      setVisible( true );
   }
   // 處理連接
   public void connectServer()
   {
       try {
         // 創建一個ServerSocket.
         toserver = new ServerSocket( 4000, 100 );
         while ( true ) {
            // 等待連接
            wait4Connection();
            // 獲取輸入輸出流
            getStreams();
            // 處理連接
            processConnection();
            // 關閉連接
            closeConnection();
            ++counter;
         }
      }

      catch ( EOFException eofException ) {
         System.out.println( "Client terminated connection" );
      }
      //捕獲異常
      catch ( IOException ioException ) {
         ioException.printStackTrace();
      }
   }

   private void wait4Connection() throws IOException
   {
      outFrame.setText( "等待連接……\n" );

      connection = toserver.accept();

      outFrame.append( "Connection " + counter +
         "from: " +
         connection.getInetAddress().getHostName()
    );
   }

   private void getStreams() throws IOException
   {
      // 設置輸出流
      outputS = new ObjectOutputStream(
         connection.getOutputStream()
      );
      outputS.flush();
      // 設置輸入流
      inputS = new ObjectInputStream(
         connection.getInputStream()
      );
      outFrame.append( "\nGet I/O streams\n" );
   }

   //處理客戶端連接
   private void processConnection() throws IOException
   {
      // 連接成功
      String message = "服務器端>> 連接成功";
      outputS.writeObject( message );
      outputS.flush();

      // 輸入框
      inputBox.setEnabled( true );

      // 處理來自客戶端的信息
      do {
         // 讀取消息
         try {
            message = ( String ) inputS.readObject();

            outFrame.append( "\n" + message );
            outFrame.setCaretPosition(
               outFrame.getText().length()
          );
         }

         catch ( ClassNotFoundException classNotFoundException ) {
            outFrame.append( "\nUnknown object type received" );
         }
      } while ( !message.equals( "客戶端>> TERMINATE" ) );
   }

   // 關閉socket
   private void closeConnection() throws IOException
   {
      outFrame.append( "\nUser terminated connection" );
      inputBox.setEnabled( false );
      outputS.close();
      inputS.close();
      connection.close();
   }

   // 向客戶端發送消息
   private void sendMsg( String message )
   {
      try {
         outputS.writeObject( "服務器端>> " + message );
         outputS.flush();
         outFrame.append( "\n服務器端>>" + message );
      }

      catch ( IOException ioException ) {
         outFrame.append( "\nError writing object" );
      }
   }

   // main()方法
   public static void main( String args[] )
   {
      ChatServer process = new ChatServer();

      process.setDefaultCloseOperation(
         JFrame.EXIT_ON_CLOSE );

      process.connectServer();
   }

}  // end class ChatServer