java socket实现全双工通信

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单工、半双工和全双工的定义

假设在通信过程的随意时刻，信息仅仅能由一方A传到还有一方B。则称为单工。

假设在随意时刻，信息既可由A传到B，又能由B传A。但仅仅能由一个方向上的传输存在，称为半双工传输。

假设在随意时刻，线路上存在A到B和B到A的双向信号传输，则称为全双工。

用swing 做的简单界面 实现了client和server端全双工通信。

Server端代码：

package cn.cblue.net1;

import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;

/**  
 * @Description: 服务端
 * @author huangzjb [e-mail]
 * @Company Digital China
 * @date 2014-6-4 下午02:18:06
 * @version 1.0
 */

public class MyServer extends JFrame implements ActionListener {
  JTextArea jta = null;
  JTextField jtf = null;
  JButton jb = null;
  JPanel jp1 = null;
  JScrollPane jsp = null;
  PrintWriter pw = null;

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

  public MyServer() {
    jta = new JTextArea();

    jsp = new JScrollPane(jta);
    jtf = new JTextField(10);
    // 注冊回车事件
    jtf.addKeyListener(new KeyListener() {

      @Override
      public void keyTyped(KeyEvent e) {
      }

      @Override
      public void keyReleased(KeyEvent e) {
      }

      @Override
      public void keyPressed(KeyEvent e) {
        if (e.getKeyCode() == KeyEvent.VK_ENTER) {
          sendMessage();
        }
      }
    });
    jb = new JButton("发送");
    jb.addActionListener(this);// 注冊一个监听事件

    jp1 = new JPanel();
    jp1.add(jtf);
    jp1.add(jb);
    this.add(jsp, BorderLayout.CENTER);
    this.add(jp1, BorderLayout.SOUTH);
    this.setTitle("chat server");
    this.setSize(300, 200);
    this.setVisible(true);

    // 接收从client发送过来的消息
    try {
      ServerSocket ss = new ServerSocket(2222);
      Socket s = ss.accept();
      BufferedReader in = new BufferedReader(new InputStreamReader(s
          .getInputStream()));
      pw = new PrintWriter(s.getOutputStream(), true);// 写成pw = new PrintWriter(s.getOutputStream())会有问题
      while (true) {
        String info = in.readLine();
        String str = null;
        if (jta.getText() == null || "".equals(jta.getText())) {
          str = "Server:" + info;
        } else {
          str = jta.getText() + "\r\nServer:" + info;
        }
        jta.setText(str);
        jta.setCaretPosition(jta.getDocument().getLength());
      }

    } catch (IOException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }

  }

  // 把信息给client
  @Override
  public void actionPerformed(ActionEvent e) {
    // TODO Auto-generated method stub
    if (e.getSource() == jb) {
      sendMessage();
    }
  }

  /**
   * @Description: 发送消息给client
   * @throws
   */
  public void sendMessage() {
    String info = jtf.getText();
    pw.println(info);
    pw.flush();
    jtf.setText("");
    if (jta.getText() == null || "".equals(jta.getText())) {
      jta.append("Client:" + info);
    } else {
      jta.append("\r\nClient:" + info);
    }

    jta.setCaretPosition(jta.getDocument().getLength());// 设置滚动栏自己主动滚动
  }
}

Client端代码：

package cn.cblue.net1;

import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;

/**  
 * @Description: client
 * @author huangzjb [e-mail]
 * @Company Digital China
 * @date 2014-6-4 下午02:18:24
 * @version 1.0
 */

public class MyClient extends JFrame implements ActionListener {

  JTextArea jta = null;
  JTextField jtf = null;
  JButton jb = null;
  JPanel jp1 = null;
  JScrollPane jsp = null;
  PrintWriter pw = null;

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

  public MyClient() {
    jta = new JTextArea();
    jsp = new JScrollPane(jta);
    jtf = new JTextField(10);
    // 注冊回车事件
    jtf.addKeyListener(new KeyListener() {
      @Override
      public void keyTyped(KeyEvent e) {

      }

      @Override
      public void keyReleased(KeyEvent e) {

      }

      @Override
      public void keyPressed(KeyEvent e) {
        if (e.getKeyCode() == KeyEvent.VK_ENTER) {
          sendMessage();
        }
      }
    });

    jb = new JButton("发送");
    jb.addActionListener(this);// 注冊一个监听事件

    jp1 = new JPanel();
    jp1.add(jtf);
    jp1.add(jb);
    this.add(jsp, BorderLayout.CENTER);
    this.add(jp1, BorderLayout.SOUTH);
    this.setTitle("chat client");
    this.setSize(300, 200);
    this.setVisible(true);

    // 接收从服务端发送过来的消息
    try {
      Socket s = new Socket("127.0.0.1", 2222);
      BufferedReader in = new BufferedReader(new InputStreamReader(s
          .getInputStream()));
      pw = new PrintWriter(s.getOutputStream(), true);
      while (true) {
        String info = in.readLine();
        String str = null;
        if (jta.getText() == null || "".equals(jta.getText())) {
          str = "Server:" + info;
        } else {
          str = jta.getText() + "\r\nServer:" + info;
        }
        jta.setText(str);
        jta.setCaretPosition(jta.getDocument().getLength());
      }

    } catch (IOException e) {
      e.printStackTrace();
    }

  }

  // 把信息给server端
  @Override
  public void actionPerformed(ActionEvent e) {
    if (e.getSource() == jb) {
      sendMessage();

    }
  }


  /**
   * @Description: 发送消息给server端
   * @throws
   */
  public void sendMessage() {
      String info = jtf.getText();
      pw.println(info);
      pw.flush();
      jtf.setText("");
      if (jta.getText() == null || "".equals(jta.getText())) {
        jta.append("Client:" + info);
      } else {
        jta.append("\r\nClient:" + info);
      }
      jta.setCaretPosition(jta.getDocument().getLength());// 设置滚动栏自己主动滚动
    }

}