//-----------網(wǎng)絡(luò) 1--------------
import java.net.*;
import java.io.*;

public class a {
    public static void main(String[] args) throws Exception {

     URL web = new URL("http://www.tsinghua.edu.cn:100");
     System.out.println(web.getProtocol());           
     System.out.println(web.getHost());           
     System.out.println(web.getPort());           
     System.out.println(web.getFile());

     BufferedReader in = new BufferedReader(
                new InputStreamReader(web.openStream()));
     String inputLine;
     while ((inputLine = in.readLine()) != null)
	    System.out.println(inputLine);
     in.close();
    }
}

-----------------------2--------------------------
import java.io.*;
import java.net.*;
public class a {
    public static void main(String[] args) throws Exception {
	if (args.length != 1) {
		System.err.println("Usage:  java Reverse string_to_reverse");
		System.exit(1);	
	}

        String stringToReverse=args[0];

	URL url = new URL("http://java.sun.com/cgi-bin/backwards");
	URLConnection connection = url.openConnection();
        connection.setDoOutput(true);

        PrintWriter to_cgi = new PrintWriter(connection.getOutputStream());
    to_cgi.println("string=" + stringToReverse); 
	to_cgi.close();
	
        BufferedReader from_cgi = new BufferedReader(    
                        new InputStreamReader(connection.getInputStream())); 
	String inputLine;
	while ((inputLine = from_cgi.readLine()) != null)	    
		System.out.println(inputLine);
	from_cgi.close();    
   }
}
//----------------3-----------------------
import java.net.*;
class a{
  public static void main(String[] args){
    try{
      InetAddress ip1=InetAddress.getLocalHost();
      System.out.println(ip1.getHostAddress());         //166.111.3.193
      System.out.println(ip1.getHostName());            //wxy0
      System.out.println(ip1);

      InetAddress ip2=InetAddress.getByName("ccf.tsinghua.edu.cn");
      System.out.println(ip2.getHostAddress());  //166.111.4.118
      System.out.println(ip2.getHostName());     //ccf.tsinghua.edu.cn

      InetAddress ip3=InetAddress.getByName("www.tsinghua.edu.cn");
      System.out.println(ip3.getHostAddress());  //166.111.4.100

      InetAddress ip4=InetAddress.getByName("mail.tsinghua.edu.cn");
      System.out.println(ip3.getHostAddress());  
      
    }catch(Exception e){}
  }
}

//---------------------4--------------------
import java.io.”
import java.net.*
public class c {
  pbulic static void main(String args[]) {
  try {
    Socket socket = new Socket(“127.0.0.1”,8888);
    BufferedReader sin = new BufferedReader (
       new  InputStreamReader( socket.getInputStream()));
    PrintWriter sout = new PrintWriter (
                                            socket.getOutputStream()  );
    BufferedReader input = new BufferedReader (
           new  InputStreamReader( System.in) );
String ask =input.readln();
    while (!ask.equals(“end”)) {
      sout.println(ask);
      sout.flush();  
      System.out.println(“server answer:   ”   +
                                           sin.readline()  );
      ask =input.readline();
    }
    sin.close();     sout.close();      socket.close();
  } catch (Exception e) { }
  }  //main
} //class c
import java.io.”
import java.net.*
public class s {
  pbulic static void main(String args[]) {
    try {
      ServerSocket ss = new  ServerSocket(8888);
      Socket  socket = ss.accept();        //
      BufferedReader cin = new BufferedReader (new
          InputStreamReader( socket.getInputStream()));
      PrintWriter cout = new PrintWriter (
                                            socket.getOutputStream()  );
      BufferedReader input = new BufferedReader (
           new  InputStreamReader( System.in) )
String answer ,ask ;
    while (!ask.equals(“bye”)) {
      ask = cin.readline()
      System.out.println(“client ask :” + ask );
      answer = input.readline() ;
      cout.println(answer);
      cout.flush();  
    }
    cin.close();     cout.close();     
    socket.close();  ss.close() ;
  } catch (Exception e) { }
  }  //main
} //class s

//-----------------------5-------------------
//------------client --------------------
import java.awt.*;
import java.net.*;
import java.io.*;
import java.awt.event.*;

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

class MyClient extends Frame
{
  Socket ClientSocket;
  PrintWriter output;
  BufferedReader input;
  String s;
  TextArea textArea1;
  TextArea textArea2;
  Button MyButton = new Button("Send Message");

  public MyClient(){
    setTitle("Client Window");		//建立并顯示與Server通訊的信息窗口
    setSize(300,250);
    setLayout(new BorderLayout());
    textArea1=new TextArea(7,30);
    textArea2=new TextArea(3,30);
    add("North",textArea1);
    add("Center",textArea2);
    add("South",MyButton);
    addWindowListener(new wd());
    MyButton.addActionListener(new ButtonClick());
    textArea2.addFocusListener(new TextFocus());
    setVisible(true);
    textArea1.setEditable(false);
    textArea2.requestFocus();
    connectToServer();       //與Server端連接通訊
  }
	
  public void connectToServer() {
    try {       
      ClientSocket=new Socket(InetAddress.getLocalHost(),8000);	
                                   //連向Server主機(jī)的8000端口
      output=new PrintWriter(
        new OutputStreamWriter(ClientSocket.getOutputStream()));
      input=new BufferedReader(
        new InputStreamReader(ClientSocket.getInputStream()));
      s=input.readLine();          //從Server端讀入數(shù)據(jù)
      textArea1.append(s+"\n");
    } catch(Exception e){}	
  }

  class ButtonClick implements ActionListener{
    public void actionPerformed(ActionEvent e) {
      try {
        output.println(textArea2.getText());
        output.flush();
        s=input.readLine();
        while(s.equals("")){
          Thread.sleep(100);
          s=input.readLine() ;
        }
        textArea1.append(s+"\n");
      } catch(Exception ex){}
    }
  }

  class TextFocus  extends FocusAdapter{
    public void focusGained(FocusEvent e){
      textArea2.setText("");
    }
  }

  class wd extends WindowAdapter {        // To close the application
    public void windowClosing(WindowEvent e) {
      try{
        output.println("Bye");
        output.flush();
        input.close();
        output.close();
        ClientSocket.close();
      } catch(Exception ex){}
      System.exit(0);
    }
  }
}
//------------------server-----------
import java.io.*;
import java.net.*;
import java.awt.*;
import java.awt.event.*;

class s {
  public static void main(String args[]) {
    new ServerService(8000,10);
  }
}

class ServerService extends Frame {
  ServerSocket m_sListener;		//監(jiān)聽服務(wù)程序
  TextArea ListenerMeg;			//監(jiān)聽程序窗口
  ServerService(int port,int cnum) {
    try{ 
       m_sListener= new ServerSocket(port,cnum);  //建立監(jiān)聽服務(wù)
       setTitle("Server Listener");		
       setSize(300,200);
       ListenerMeg = new TextArea("Server is listening on port "
                                        + port + "\n",10,50);
       add("Center",ListenerMeg);
       addWindowListener(new wd());
       setVisible(true);
       while(true) {
          Socket Connected = m_sListener.accept();//接受來自Client端的請求
          InetAddress ClientAddress = Connected.getInetAddress();
          ListenerMeg.append( "Client " + " connected" + 
                              " from \n"+ ClientAddress.toString() + " .\n" );
          ServiceThread sThread = new ServiceThread(this,Connected);
                                        //為與此Client通訊建立新線程
          new Thread(sThread).start() ;    //啟動新線程
       }
    }catch(IOException e){}
  }

  public void addMeg(String s){	 //在監(jiān)聽器窗口中加入信息
    ListenerMeg.append(s);
  }

  class wd extends WindowAdapter {        // To close the application:
    public void windowClosing(WindowEvent e) {
      System.exit(0);
    }
  }  
}   //ServerSerive Class

class ServiceThread extends Frame implements Runnable  {
  ServerService fss;	 //當(dāng)前線程的父窗口
  Socket tSocket;	         //當(dāng)前線程負(fù)責(zé)通訊的Socket
  InetAddress cadd ;           //client端ip
  TextArea tMeg;		 //當(dāng)前線程信息顯示窗口的文本區(qū)域

  public ServiceThread (ServerService ss, Socket s ) {
    fss = ss ;
    tSocket = s;
    setSize(300,200);
    tMeg = new TextArea(10,50);
    add("Center",tMeg);
    cadd = tSocket.getInetAddress();
    setTitle(" For client:" + cadd.getHostName());  
    setVisible(true);
  }

  public void run(){     //與Client端通訊
    try	{
      BufferedReader in = new BufferedReader ( 
                  new InputStreamReader(tSocket.getInputStream()));
      PrintWriter out = new PrintWriter (tSocket.getOutputStream());
      out.println("Hello! Welcome to get server information service.\r");
      out.flush();	//向Client端輸出信息
      String s = in.readLine(); //從Client端讀入信息
      while (!s.equals("bye"))	{   
        out.println("You've send the following message:" + s);
        out.flush();
        tMeg.append("Client is saying: \n"+ s + "\n");
        s = in.readLine();
      }
      out.println("good bye ");
      out.flush();
      tSocket.close();  //若Client端寫入“bye”則結(jié)束通訊
    }catch(Exception e){}
    fss.addMeg( "Client " + cadd.toString() + " closed." + "\n" );
    dispose();//close Frame
  }//run()
}
-----------------運(yùn)行說明--------------
打開一個(gè)DOS窗口，啟動服務(wù)器程序 s.class
打開一個(gè)DOS窗口，啟動一個(gè)客戶端程序 c.class
打開一個(gè)DOS窗口，再啟動一個(gè)客戶端程序 c.class
  ......