看到现在很多朋友都在问socket的问题，因此自己写了个用socket搭建服务器的基础程序供大家参考。程序只实现了简单的接收然后广播。

小弟水平有限，还望大家不吝赐教。程序如下：

import java.net.*;
import java.io.*;
import java.util.*;
public class SocketServer2 extends Thread{
   Vector v = null;
   ServerSocket ss = null;  
  public SocketServer2() {
    v = new Vector();
     try{
     ss = new ServerSocket(8000);
     }catch(Exception e){System.out.println(e);}
     this.start();
  }

  public static void main(String[] args) {
        new SocketServer2();        
  }
  public void run()
  {
   try{      
      while(true)
            {
              /* 为各个客户端建立连接并用Vector存储相关信息,据<thinking in java>上说ArrayList更好，不过我对ArrayList不熟，就将就用Vector了　*/

              Socket sc = ss.accept();
              InputStream is = sc.getInputStream();            
              OutputStream os = sc.getOutputStream() ;
              Exchange ct = new Exchange(this,is,os);
              v.addElement(ct);            
            }           
    }
    catch(Exception e){}
  }  
  public void sendMsg(String str){
/* 利用存储的各个流信息进行广播 */ 

for(int i=0;i<v.size();i++){
  Exchange eg = (Exchange)v.elementAt(i);
  try{
  System.out.println(str); 
  eg.os.write((str+"\n").getBytes());
     }catch(Exception e){}
 }
  }  
  
}
/* 每个线程控制一个连接，独自实现接收和广播　*/

class Exchange extends Thread{
  SocketServer2 s=null;
  InputStream is = null;
  OutputStream os = null;
  Exchange(SocketServer2 s,
               InputStream is,
               OutputStream os){
   this.s = s;
   this.is = is;
   this.os = os;
   this.start();
   }
  public void run(){
   while(true){
       try{
       DataInputStream dis = new DataInputStream(is) ;
                String sb="";
                int c=0;
                while (((c = is.read()) != '\n') && (c != -1)) {
                    sb=sb+(char)c;
                }
                if (c == -1) {                   
                    break;
                }
              
              s.sendMsg(sb);
    }
    catch(Exception e){System.out.println(e);}
   }
  }  
}