# 创建UDP服务器

建议先阅读官方文档的以下章节.

* [创建UDP服务器](https://wiki.swoole.com/wiki/page/477.html)

## 创建UDP服务器

```php
<?php

//创建Server对象，监听 0.0.0.0:9501端口
$serv = new swoole_server("0.0.0.0", 9501,SWOOLE_PROCESS,SWOOLE_SOCK_UDP);

//配置
$serv->set([
    'worker_num' => 2, //设置进程
]);

//接收到udp数据的时候触发
$serv->on('Packet',function ($serv,$data,$clientInfo){
        //var_dump($data,$clientInfo);
        $serv->sendto($clientInfo['address'],$clientInfo['port'],'服务端udp数据包');
});

//启动服务器
$serv->start();
```

UDP服务器与TCP服务器不同，UDP没有连接的概念。启动Server后，客户端无需Connect，直接可以向Server监听的9502端口发送数据包。对应的事件为onPacket。

* `$clientInfo`是客户端的相关信息，是一个数组，有客户端的IP和端口等内容
* 调用`$server->sendto`方法向客户端发送数据

## 创建UDP客户端

```php
$client = new swoole_client(SWOOLE_SOCK_UDP, SWOOLE_SOCK_SYNC);

//不计后果
var_dump($client->sendto('127.0.0.1', 9501,'udp数据'));
//从服务端接收数据
$response = $client->recv();

// 输出接受到的数据
echo $response . PHP_EOL;
```


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