广播类,封装了信息转发和userList管理的方法--BroadCast

import java.io.IOException;
import java.io.PrintStream;
import java.util.Enumeration;
import java.util.Vector;
/*
 *
 * @author zhang
 *
 * 广播类,封装了信息转发和userList管理的方法
 */
public class Broadcast
{
    private Vector userList = null;
    private final int MAX_SIZE=200;
    private final int MIN_LEN=20;
    private static Broadcast broadcast=null;
    public Broadcast()
    {
        userList = new Vector(MIN_LEN);
    }
    public static Broadcast getInstence(){
     if(broadcast==null) return new Broadcast();
     return broadcast;
    }

    public synchronized boolean addUser(Angent angent)
    {
     if(this.userList.size()==200) return false;
        for(Enumeration enumeration = userList.elements(); enumeration.hasMoreElements();)
            if(((Angent)enumeration.nextElement()).getUserId().compareTo(angent.getUserId()) == 0)
                return false;//如果有相同的用户名
        //第一次登录:   
        userList.addElement(angent);
        return true;
    }

    public synchronized void broadcast(String s)
    {sendOther(s,null);}

    public synchronized int getUserNumber()
    {
        return userList.size();
    }

    public synchronized void removeUser(Angent angent)
    { //删除用户
        userList.removeElement(angent);
    }

    public synchronized void sendTo(String s, String toUser)
    {
        for(Enumeration enumeration = userList.elements(); enumeration.hasMoreElements();)
        {   //angent是目标代理
            Angent angent = (Angent)enumeration.nextElement();
            if(angent.getUserId().equals(toUser))
            {
                angent.getOut().println(s);
                break;
            }
        }

    }

    public synchronized void sendOther(String s,Angent angent)
    {
        for(Enumeration enumeration = userList.elements(); enumeration.hasMoreElements();)
        {
            Angent angent1 = (Angent)enumeration.nextElement();
           
            if((!angent.getUserId().equals(angent.getUserId())))
            { //保证不发送给本人,节省了带宽
                angent.getOut().println(s);
            }
        }

    }
}