client.java

实现PKI/CA的数字签名部分

package dssserver;

import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.PrintStream;
import java.net.Socket;
import java.util.StringTokenizer;

//实现 Client线程类
class Client implements Runnable{                            
	Socket socket;                             	   //用来存储一个连接客户的socket信息
	String name;                             	   //用来存储客户的连接姓名
	String pswd;
	String ip;   
	String info ;                                  //用来存储客户的ip信息
	BufferedInputStream in;                        //用来实现接受从客户端发来的数据流
	PrintStream out;
	
	byte[] inBytes=new byte[500];
	static String ENC="GB2312";
	
	Thread thread;
	ServerMain smparent; 
	DataBase db;
	
	void thstop(){//线程停止
		thread=null;
	}
	
	void start(){//线程启动
		thread = new Thread(this);
		thread.start();
	}
	
	public  Client(Socket s,ServerMain sa){                            //Client线程类的构造器
		smparent = sa;
		socket = s;                                      
		try{
			in = new BufferedInputStream(s.getInputStream());     	 //存储特定客户socket的输入流接受s这个客户发送到服务器端的信息
			out = new PrintStream(s.getOutputStream());      	    	 //存储特定客户socket的输出流发送服务器给s这个客户的信息
			in.read(inBytes); //从(ip 端口)得到数据
			info = new String(inBytes,ENC);
			StringTokenizer stinfo = new StringTokenizer(info,":");  //用StringTokenizer类来读取用"："分段字符
			String head = stinfo.nextToken();                        //head用来存储类似于关键字的头信息
			db = new DataBase();			   
			if(head.equals("INFO")){
				if(stinfo.hasMoreTokens())
					name = stinfo.nextToken();                         //关键字后的第二段数据是客户名信息
				if(stinfo.hasMoreTokens())
					pswd = stinfo.nextToken();			   	              
				if(stinfo.hasMoreTokens())
					ip = stinfo.nextToken();                            //关键字后的第四段数据是客户ip信息	   		   
				
				if(db.checkuser(this))//把this就是当前类的变量值, 他里面有变量的值
					send("SUC:"); //向(ip 端口)写数据
				else
					send("REFUSE:");			   
			}
			else if(head.equals("REG")){
				String username=stinfo.nextToken();
				String userpswd=stinfo.nextToken();
				db.reguser(username,userpswd);	
				s.close();		   	
			}
		}
		catch(IOException e)
		{
			System.out.println("网络I/O错误:"+e);
		}
	}
	
	public void send(String msg){                   //实现向客户端发送信息的方法
		out.print(msg);
		out.flush();
	}

	public void run(){
		Thread thisThread = Thread.currentThread();
		while(thread == thisThread){
			String line = null;   //用来的到客户端发来的信息
			try{
				in.read(inBytes);
				line = new String(inBytes,ENC);       
			   }
			catch(IOException e){
				System.out.println("网络I/O错误"+e);
				smparent.notifyOthers(this,"QUIT");
				smparent.disconnect(this);
				return;
			}

			if(line == null){    //客户已离开
				smparent.notifyOthers(this,"QUIT");
				smparent.disconnect(this);
				return;
			}
		   
			StringTokenizer st=new StringTokenizer(line,":");    //的到客户端发来的信息, 用StringTokenizer分开
			String keyword=st.nextToken();
			
			
			if(keyword.equals("MSG")){                          //如果关键字是MSG则是客户端发来的聊天信息
				String toname=st.nextToken();
				if(smparent.clientName.contains(toname)){
					int index=smparent.clientName.indexOf(toname);
					Client c=((Client)smparent.clients.elementAt(index));
					c.send(line);                 
				}
				else{
					String errString="ERROR:"+st.nextToken()+":"+toname+":"+"我下线了"+":";
					send(errString);
				   }
			}    
			else if(keyword.equals("QUIT")){
				smparent.notifyOthers(this, "QUIT");
				smparent.disconnect(this);                                  
			}
			
			else if(keyword.equals("ASKFOR")){    //选择和谁对话
				String peo= "EXIST:"+smparent.clientName.size();
				for(int i= 0;i<smparent.clientName.size();i++){
					peo=peo+":"+smparent.clientName.elementAt(i);
				}
				peo=peo+":";
				send(peo); 
				smparent.notifyOthers(this,"NEW");
				try{
					smparent.clients.addElement(this);
					smparent.clientName.addElement(this.name);
				}
				catch(NullPointerException e){                           
				}		
			}
			
			
			
			else if(keyword.equals("FILE_TO")){  //文件发送
				String toname=st.nextToken();
				String me=st.nextToken();
				if(smparent.clientName.contains(toname)){
					int index=smparent.clientName.indexOf(toname);
					Client c=((Client)smparent.clients.elementAt(index));				
					c.send(line);							    	
				}							    
			}
			
			else if(keyword.equals("FILE_FROM")){  //接收文件
				String toname=st.nextToken();
				String me=st.nextToken();
				if(smparent.clientName.contains(toname)){
					int index=smparent.clientName.indexOf(toname);
					Client c=((Client)smparent.clients.elementAt(index));				
					c.send(line);							    	
				}				
			}
		}
	}
	
	public boolean checkName(){               //检查是否有相同的用户连接
		if(smparent.clientName.contains(name)||(name == "SERVERSHUTDOWN"))
			return false;
		else return true;
	}
}