迭代器的方式会产生锁定

服务器端增加发送给每个客户端已收到信息的功能

所以当获取到一个socket，并打开它的线程进行循环接收客户端发来信息时，我们把这个内部类的线程Client保存到集合List<Client>中

然后在读取到客户端信息后，把这个信息发送给所有端口

通过循环

for(int i=0;i<clients.size();i++){

　　Client c=clients.get(i);

　　c.send(str);

}

发送给每一个已经成功连接到服务端的客户端

服务端详细的代码修改如下：

package com.swift;import java.io.DataInputStream;import java.io.DataOutputStream;import java.io.EOFException;import java.io.IOException;import java.net.BindException;import java.net.ServerSocket;import java.net.Socket;import java.util.ArrayList;import java.util.Iterator;import java.util.List;public class ChatServer {        boolean started = false;    ServerSocket ss = null;    Socket s = null;    List
     
       clients=new ArrayList
      
       ();          public static void main(String[] args) {        new ChatServer().fun();    }    private void fun() {        try {            ss = new ServerSocket(8888);            started = true;        } catch (BindException e) {            System.out.println("端口使用中......");        } catch (IOException e1) {            e1.printStackTrace();        }        try {            while (started) {                s = ss.accept();                System.out.println("a client connected success");                Client c = new Client(s);                new Thread(c).start();                clients.add(c);            }        } catch (EOFException e) {            System.out.println("client has closed.");        } catch (Exception e) {            e.printStackTrace();        } finally {            try {                ss.close();            } catch (IOException e) {                // TODO Auto-generated catch block                e.printStackTrace();            }        }    }    class Client implements Runnable {        private Socket s;        private DataInputStream dis;        private DataOutputStream dos;        private boolean connected = false;        public Client(Socket s) {            this.s = s;            try {                this.dis = new DataInputStream(s.getInputStream());                this.dos = new DataOutputStream(s.getOutputStream());                connected = true;            } catch (IOException e) {                // TODO Auto-generated catch block                e.printStackTrace();            }        }        private void send(String str) {            try {                dos.writeUTF(str);            } catch (IOException e) {                // TODO Auto-generated catch block                e.printStackTrace();            };        }        @Override        public void run() {            try {
   //注意:要包括while循环，如果try在while循环里，则出现socket closed异常                while (connected) {                    String str = dis.readUTF();                    System.out.println(str);                    for(int i=0;i
       
         it=clients.iterator();it.hasNext();) {//                         Client c=it.next();//方法二，不可取，有同步锁//                         c.send(str);//                     }                    //                    Iterator
        
          it=clients.iterator();//                    while(it.hasNext()) {//                        Client c=it.next();//方法三，不可取，有同步锁,修改需要加锁（此时没修改）//                        c.send(str);//                    }                                     }            } catch (IOException e) {                e.printStackTrace();            } finally {                if (dis != null) {                    try {                        dis.close();                    } catch (IOException e) {                        e.printStackTrace();                    }                }                if (s != null) {                    try {                        s.close();                    } catch (IOException e) {                        e.printStackTrace();                    }                }                if(dos!=null) {                    try {                        dos.close();                    } catch (IOException e) {                        e.printStackTrace();                    }                }            }        }    }}