/* 聊天程序之客戶端ChatClient.java
 * 建立客戶端以獲取服務器端發送信息并顯示
*/

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

public class ChatClient extends JFrame {
   private JTextField inputBox;
   private JTextArea outFrame;
   private ObjectOutputStream outputS;
   private ObjectInputStream inputS;
   private String message = "";
   private String chatServer;
   private Socket toclient;

   // 初始化聊天服務
   public ChatClient( String srvhost )
   {
      super( "Client" );

      chatServer = srvhost;
      // 設置客戶端連接的服務器
      Container container = getContentPane();

      inputBox = new JTextField();
      // 建立輸入框
      inputBox.setEnabled( false );
      inputBox.addActionListener(
      //監聽
         new ActionListener() {
            public void actionPerformed( ActionEvent event )
            {
               sendMsg( event.getActionCommand() );
            }
            // 向服務器端發送消息
         }
      );
      container.add( inputBox, BorderLayout.NORTH );

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

      setSize( 280, 160 );
      setVisible( true );
      // 輸出輸出框
   }

   // 連接服務器端
   public void connectClient()
   {
      try {
         // 創建用于連接的Socket
         connect2Server();
         // 得到輸入輸出流
         getStreams();
         // 建立連接
         processConnection();
         // 關閉連接
         closeConnection();
      }
      catch ( EOFException eofException ) {
         System.out.println( "Server terminated connection" );
      }
      catch ( IOException ioException ) {
         ioException.printStackTrace();
      }
      //捕獲異常
   }

   // 獲取輸入輸出流
   private void getStreams() throws IOException
   {
      // 輸出
      outputS = new ObjectOutputStream(
         toclient.getOutputStream() );

      outputS.flush();

      // 輸入
      inputS = new ObjectInputStream(
         toclient.getInputStream() );

      outFrame.append( "\nGet I/O streams\n" );
   }

   // 連接服務器端
   private void connect2Server() throws IOException
   {
      outFrame.setText( "連接中……\n" );
      toclient = new Socket(
         InetAddress.getByName( chatServer ), 4000 );
      // 連接信息顯示
      outFrame.append( "連接至: " +
         toclient.getInetAddress().getHostName() );
   }

   private void processConnection() throws IOException
   {
      // 輸出框
      inputBox.setEnabled( true );
      do {
         // 讀入信息并輸出
         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( "服務器端>> TERMINATE" ) );
   }
//關閉輸入輸出流、關閉連接，注意順序
   private void closeConnection() throws IOException
   {
      outFrame.append( "\n關閉連接" );
      outputS.close();
      inputS.close();
      toclient.close();
   }

   // 給服務器端發消息
   private void sendMsg( String message )
   {
      try {
         outputS.writeObject( "客戶端>> " + message );
         outputS.flush();
         outFrame.append( "\n客戶端>>" + message );
      }
      catch ( IOException ioException ) {
         outFrame.append( "\nError writing object" );
      }
   }

   //main()方法
   public static void main( String args[] )
   {
      ChatClient beginning;

      if ( args.length == 0 )
         beginning = new ChatClient( "127.0.0.1" );
      else
         beginning = new ChatClient( args[ 0 ] );

      beginning.setDefaultCloseOperation(
         JFrame.EXIT_ON_CLOSE );

      beginning.connectClient();
   }

}  // end class ChatClient