server.java

JAVA的高级应用以及网络编程

import java.io.*;
import java.net.*;
class server{
	ServerSocket server_socket;
	String user[]; 
	static int client_counter=0;
	InputStream net_input[]; 
	OutputStream net_output[];
	public static void main(String args[]){
		new server();
	}
	public server(){
		user=new String[2];
		net_input=new InputStream[2];
		net_output=new OutputStream[2];
		try{
			server_socket=new ServerSocket(1111);
		}
		catch(IOException e){
			System.out.println("Error in server socket"); 
			return;
		}
		System.out.println("waiting for users...");
		while(true){
			try{
				Socket socket=server_socket.accept();
				service_request(socket);
			}
			catch(IOException e){
				System.out.println("Exception:<"+e+">"); 
				break;
			}
		}
	}
	public void service_request(Socket socket){
		InputStream input;
		OutputStream output;
		try{
			input=socket.getInputStream(); 
			output=socket.getOutputStream();
			}
		catch(IOException e){
			System.out.println("Unable to get input/output streams");
			return;
		}
		if(client_counter>=2){
			write_net_output(output,"There are already two clients");
			return;
		}
		net_input[client_counter]=input;
		net_output[client_counter]=output;
		user[client_counter]=read_net_input_line(input);
		System.out.println(user[client_counter]+" Connected!"+socket.toString());
		(new reader(this,client_counter)).start();
		int c=client_counter++;
	}
	String read_net_input_line(InputStream input){
		String line="";
		String c;
		c=read_net_input(input);
		while((byte)c.charAt(0)!=10){
			line=line+c;
			c=read_net_input(input);
		}
		return line;
	}
	String read_net_input(InputStream input){
		byte bytes[]; 
		int number_of_bytes;
		try{
			bytes=new byte[1];
			number_of_bytes=input.read(bytes,0,1);
			if(number_of_bytes>0){
				String s=new String(bytes,0,0,number_of_bytes);
				return(s);
			}
			    
			else  
			    return null;
		}
		catch(IOException e){
			return null;
		}
	}
	void write_net_output(OutputStream output,String string){
		byte byte_array[];
		int length=string.length();
		byte_array=new byte[length];
		string.getBytes(0,length,byte_array,0);
		try{
			output.write(byte_array);
		}
		catch(IOException e){;}
	}
}

class reader extends Thread{
	server s; 
	int index;
	public reader(server s, int index){
		this.s=s;	
		this.index=index;
	}
	public void run(){
		setPriority(MIN_PRIORITY);
		s.write_net_output(s.net_output[index],"WAIT");
		while (s.client_counter<2){
			s.write_net_output(s.net_output[index],"   GO...");
			while(true){
				String string=s.read_net_input(s.net_input[index]);
				if(string==null) break;
				System.out.println(s.user[index]+":"+string);
				s.write_net_output(s.net_output[(index+1)%2],string);
			}
			System.out.println(s.user[index]+" has disconnected.");
			s.user[index]=null;
			if(--s.client_counter==0)  
			    System.exit(0);
		}
	}
}