#!/usr/bin/env php <?php //author:zhxia if(!extension_loaded('sockets')){     die('the sockets extension is not loaded!'); } const PORT=9981; $socket=socket_create(AF_INET,SOCK_STREAM,SOL_TCP) or die('socket create error!'); #通过设置这个选项，进行端口的重用 socket_set_option($socket,SOL_SOCKET,SO_REUSEADDR,1); socket_bind($socket,0,PORT); socket_listen($socket); #使用非阻塞模式 socket_set_nonblock($socket); echo 'listen on port '.PORT.'...'.PHP_EOL; $clients=array($socket); while(TRUE){     $read=$clients;     $write=$except=array();     //通过select系统调用，检测socket的状态是否改变     if(socket_select($read,$write,$except,0)<1){         continue;     }     //检测是否有客户端来进行连接     if(in_array($socket,$read)){         $clients[]=$newsocket=socket_accept($socket);         socket_write($newsocket,"welcome!\nthere are ".(count($clients)-1)." client here\n");         socket_getpeername($newsocket,$ip);         echo "new client connected:$ip\n";         $key=array_search($newsocket,$read);         unset($read[$key]);     }     foreach($read as $read_socket){         $data=@socket_read($read_socket,1024,PHP_NORMAL_READ);         if($data===false){             //如果没有取到数据，说明该客户端已经断开             $key=array_search($read_socket,$clients);             unset($clients[$key]);             echo "client disconnectd.\n";             continue;         }         $data=trim($data);         if(!empty($data)){             foreach($clients as $write_socket){                 //排除服务器端和自身,然后将数据发送给所有的其他客户端                 if($write_socket==$socket||$write_socket==$read_socket){                     continue;                 }                 socket_write($write_socket,"$data\n");             }         }     } } socket_close($socket);