client.java

它能够进行简单的文字聊天和基本的信息交换。

/*
 * client.java
 *
  
 *
 * To change this template, choose Tools | Template Manager
 * and open the template in the editor.
 */

/**
 *
 * @author codewar1
 */
import java.net.*;
import java.io.*;
import java.security.Security;
import java.security.*;
import javax.crypto.*;
import com.sun.crypto.provider.SunJCE;
public class client {
    String username ;
    Socket socket ;
    ObjectOutputStream output;
    ObjectInputStream input;
   // OutputStream output;
   // InputStream input;
    public String key = "nuptcodewor";
    int k;
    /** Creates a new instance of client */
    public client() {
    String username = null;
    Socket socket = null;
    ObjectOutputStream output = null;
    ObjectInputStream input = null;
    // OutputStream output = null;
    //InputStream input = null;
    k = 0;
   }
   public String encrypt(String message)
   {
       
      if (key.length()>message.length())
        {
            
             
            String longs = key+message;
            return longs;
            
             
        }
        else  
        {
           // String shorts = message.replace("a","d");
            String shorts = message+key;
            return shorts;
          // return message;
        }
        // return message;
        
         
   }
   
   public  String decrypt(String message)
   {
        int k = message.length();
        if (k<2*key.length())
        {
             
            String longs= message.substring(key.length());
            return longs;
        }
        else
        {
             
            //String shorts = message.replace("d","a");
            int p = message.indexOf(key);
            String shorts= message.substring(0,p);
            return shorts;
            // return message;
          
        }
        //return message;
      
   }
 }