# connect 方法 ```php void AsyncTcpConnection::connect() ``` 执行异步连接操作。此方法会立刻返回。 注意：如果需要设置异步连接的onError回调，则应该在connect执行之前设置，否则onError回调可能无法被触发，例如下面的例子onError回调可能无法触发，无法捕获异步连接失败事件。 ```php $connection = new AsyncTcpConnection('tcp://baidu.com:81'); // 执行连接的时候还没设置onError回调 $connection->connect(); $connection->onError = function($connection, $err_code, $err_msg) { echo "$err_code, $err_msg"; }; ``` ### 参数 无参数 ### 返回值 无返回值 ### 示例 Mysql代理 ```php use \Workerman\Worker; use \Workerman\Connection\AsyncTcpConnection; require_once __DIR__ . '/Workerman/Autoloader.php'; // 真实的mysql地址，假设这里是本机3306端口 $REAL_MYSQL_ADDRESS = 'tcp://127.0.0.1:3306'; // 代理监听本地4406端口 $proxy = new Worker('tcp://0.0.0.0:4406'); $proxy->onConnect = function($connection) { global $REAL_MYSQL_ADDRESS; // 异步建立一个到实际mysql服务器的连接 $connection_to_mysql = new AsyncTcpConnection($REAL_MYSQL_ADDRESS); // mysql连接发来数据时，转发给对应客户端的连接 $connection_to_mysql->onMessage = function($connection_to_mysql, $buffer)use($connection) { $connection->send($buffer); }; // mysql连接关闭时，关闭对应的代理到客户端的连接 $connection_to_mysql->onClose = function($connection_to_mysql)use($connection) { $connection->close(); }; // mysql连接上发生错误时，关闭对应的代理到客户端的连接 $connection_to_mysql->onError = function($connection_to_mysql)use($connection) { $connection->close(); }; // 执行异步连接 $connection_to_mysql->connect(); // 客户端发来数据时，转发给对应的mysql连接 $connection->onMessage = function($connection, $buffer)use($connection_to_mysql) { $connection_to_mysql->send($buffer); }; // 客户端连接断开时，断开对应的mysql连接 $connection->onClose = function($connection)use($connection_to_mysql) { $connection_to_mysql->close(); }; // 客户端连接发生错误时，断开对应的mysql连接 $connection->onError = function($connection)use($connection_to_mysql) { $connection_to_mysql->close(); }; }; // 运行worker Worker::runAll(); ``` **测试** ```php mysql -uroot -P4406 -h127.0.0.1 -p Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 25004 Server version: 5.5.31-1~dotdeb.0 (Debian) Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved. Oracle is a registered trademark of Oracle Corporation and/or its affiliates. Other names may be trademarks of their respective owners. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. mysql> ```