如何使用PHP实现公众号的自定义回复功能

<?php
// 验证服务器配置的有效性
$token = "my_token"; // 与微信公众号后台设置的Token一致
$signature = $_GET["signature"];
$timestamp = $_GET["timestamp"];
$nonce = $_GET["nonce"];
$echostr = $_GET["echostr"];

$tmpArr = array($token, $timestamp, $nonce);
sort($tmpArr);
$tmpStr = implode($tmpArr);
$tmpStr = sha1($tmpStr);

if ($tmpStr == $signature) {
    echo $echostr;
    exit;
}

// 处理接收到的消息和事件
$postStr = file_get_contents("php://input");
if (!empty($postStr)) {
    $postObj = simplexml_load_string($postStr, 'SimpleXMLElement', LIBXML_NOCDATA);
    $msgType = $postObj->MsgType;
    
    // 根据不同的消息类型进行回复
    switch ($msgType) {
        case "text":
            $content = $postObj->Content;
            $responseText = "您发送的消息是：" . $content;
            replyText($postObj, $responseText); // 调用回复文本消息的函数
            break;
        case "event":
            $event = $postObj->Event;
            if ($event == "subscribe") {
                $responseText = "感谢您关注我们的公众号！";
                replyText($postObj, $responseText); // 调用回复文本消息的函数
            }
            break;
        // 其他消息类型的处理
        // ...
    }
}

// 回复文本消息的函数
function replyText($postObj, $content) {
    $fromUsername = $postObj->FromUserName;
    $toUsername = $postObj->ToUserName;
    $time = time();
    
    $textTpl = "<xml>
    <ToUserName><![CDATA[%s]]></ToUserName>
    <FromUserName><![CDATA[%s]]></FromUserName>
    <CreateTime>%s</CreateTime>
    <MsgType><![CDATA[text]]></MsgType>
    <Content><![CDATA[%s]]></Content>
    </xml>";
    $resultStr = sprintf($textTpl, $fromUsername, $toUsername, $time, $content);
    echo $resultStr;
}
?>