1.1半双工原理：半双工即Half duplex Communication，是指在通信过程的任意时刻，信息既可由A传到B，又能由B传A，但只能有一个方向上的传输存在。采用半双工方式时，通信系统每一端的发送器和接收器，通过收/发开关转接到通信线上，进行方向的切换，因此，会产生时间延迟。收/发开关实际上是由软件控制的电子开关。
1.2工程结构
1.3服务器端
/*** 服务器端，在9999端口监听,可以通过控制台，回送给客户端信息 */ package test; import java.io.BufferedReader; import java.io.InputStreamReader; import java.io.PrintWriter; import java.net.ServerSocket; import java.net.Socket; public class myserver2 { public myserver2 () { try { //监听端口，9999 ServerSocket ss=new ServerSocket(9999); //阻塞，等待连接 Socket s=ss.accept(); //先接受到客户端发来的信息 InputStreamReader isr=new InputStreamReader(s.getInputStream()); BufferedReader br=new BufferedReader(isr); PrintWriter pw=new PrintWriter(s.getOutputStream(),true); InputStreamReader isr2=new InputStreamReader(System.in); BufferedReader br2=new BufferedReader(isr2); while(true){ String infoFromClient=br.readLine(); System.out.println("客户端："+infoFromClient); if(infoFromClient.equals("bye")){
s.close(); break; } //接受从控制台输入的信息 System.out.println("请输入您希望对客户端说的话:"); String re=br2.readLine(); //把从控制台接受的信息，回送给客户端 pw.println(re); } } catch (Exception e) { // TODO: handle exception } } public static void main(String[] args) { // TODO Auto-generated method stub new myserver2(); } } 1.4客户端
package test;
import java.io.BufferedReader; import java.io.InputStreamReader; import java.io.PrintWriter; import java.net.Socket; public class myclient2 { public myclient2 () { try { //连接服务器端 Socket s=new Socket("127.0.0.1",9999); PrintWriter pw=new PrintWriter(s.getOutputStream(),true); InputStreamReader isr=new InputStreamReader(System.in); BufferedReader br=new BufferedReader(isr); InputStreamReader isr2=new InputStreamReader(s.getInputStream()); BufferedReader br2=new BufferedReader(isr2); while(true){ System.out.println("请输入您要对服务器要说的话:"); //客户端先从控制台接受 String info=br.readLine(); pw.println(info); if(info.equals("bye")){
System.out.println("通话结束！"); s.close(); break; } //接受从服务器发来的信息 String res=br2.readLine(); System.out.println("服务器端："+res); } } catch (Exception e) { // TODO: handle exception } } public static void main(String[] args) { // TODO Auto-generated method stub new myclient2(); } } 2.全双工 全双工：全双工（Full Duplex）是通讯传输的一个术语。通信允许数据在两个方向上同时传输，它在能力上相当于两个单工通信方式的结合。全双工指可以同时（瞬时）进行信号的双向传输（A→B且B→A）。指A→B的同时B→A，是瞬时同步的。
2.1工程目录结构：
/** * 服务器端 */package com.test;
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.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;import javax.swing.WindowConstants;
public class myserver3 extends JFrame implements ActionListener, KeyListener {PrintWriter pw=null;JTextArea jt_aArea=new JTextArea();JTextField jTextField=new JTextField(10);JButton btn_send=new JButton("发送");JPanel jp1=new JPanel();JScrollPane jsp=new JScrollPane(jt_aArea);public myserver3 () {jp1.add(jTextField);jp1.add(btn_send);btn_send.addActionListener(this);jTextField.addKeyListener(this);this.add(jsp,"Center");this.add(jp1,"South");this.setTitle("简易服务器端");this.setSize(300, 300);this.setVisible(true);this.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);try {//服务器监听ServerSocket ss=new ServerSocket(9999);//等待客户端连接Socket s=ss.accept();InputStreamReader isr=new InputStreamReader(s.getInputStream());BufferedReader br=new BufferedReader(isr);pw=new PrintWriter(s.getOutputStream(),true);//读取从客户端发送来的信息while(true){String info =br.readLine();jt_aArea.append("客户端："+info+"\r\n");}} catch (Exception e) {// TODO: handle exception}}@Overridepublic void keyTyped(KeyEvent e) {// TODO Auto-generated method stubif(e.getSource()==jTextField){//System.out.println(e.getKeyCode());if(e.getKeyCode()==KeyEvent.VK_ENTER){String info=jTextField.getText();jt_aArea.append("服务端："+info+"\r\n");pw.println(info);//清空内存jTextField.setText("");}}}@Overridepublic void keyReleased(KeyEvent e) {// TODO Auto-generated method stub}@Overridepublic void keyPressed(KeyEvent e) {// TODO Auto-generated method stub}public void actionPerformed(ActionEvent arg) {//如果用户按下发送信息按钮if(arg.getSource()==btn_send){String info=jTextField.getText();jt_aArea.append("服务器："+info+"\r\n");pw.println(info);//清空内存jTextField.setText("");}}public static void main(String[] args) {// TODO Auto-generated method stubnew myserver3();}
}///////////////////////////////////////////////////////////////////////////////////////////////////////////////客户端：
package com.test;
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.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;import javax.swing.WindowConstants;
public class myclient3 extends JFrame implements ActionListener, KeyListener{JTextArea jt_aArea=new JTextArea();JTextField jTextField=new JTextField(10);JButton btn_send=new JButton("发送");PrintWriter pw=null;JPanel jp1=new JPanel();JScrollPane jsp=new JScrollPane(jt_aArea);public myclient3 () {jp1.add(jTextField);jp1.add(btn_send);btn_send.addActionListener(this);jTextField.addKeyListener(this);this.add(jsp,"Center");this.add(jp1,"South");this.setTitle("简易客户端");this.setSize(300, 300);this.setVisible(true);this.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);try {Socket s=new Socket("127.0.0.1",9999);InputStreamReader isr=new InputStreamReader(s.getInputStream());BufferedReader br=new BufferedReader(isr);pw=new PrintWriter(s.getOutputStream(),true);while(true){//不停的读取String info=br.readLine();jt_aArea.append("服务器端："+info+"\r\n");//换行//jt_aArea.setText(info);}} catch (Exception e) {// TODO: handle exception}}public void keyTyped(KeyEvent e) {// TODO Auto-generated method stubif(e.getSource()==jTextField){//System.out.println(e.getKeyCode());if(e.getKeyCode()==KeyEvent.VK_ENTER){String info=jTextField.getText();jt_aArea.append("客户端："+info+"\r\n");pw.println(info);//清空内存jTextField.setText("");}}}@Overridepublic void keyReleased(KeyEvent e) {// TODO Auto-generated method stub}@Overridepublic void keyPressed(KeyEvent e) {// TODO Auto-generated method stub}public void actionPerformed(ActionEvent arg) {//如果用户按下发送信息按钮if(arg.getSource()==btn_send){String info=jTextField.getText();jt_aArea.append("客户端："+info+"\r\n");pw.println(info);//清空内存jTextField.setText("");}}public static void main(String[] args) {// TODO Auto-generated method stubnew myclient3();}
}
先启动服务端，在启动客户端运行效果：
