发送字符的问题＆＃39; +＆＃39;在PHP CURL中的POST请求中

Question

我正在尝试使用PHP REST API实施航班预订API。如果我的一个POST参数包含字符＆＃39; +＆＃39;它被转换为＆＃39; ＆＃39;而不是正确传递..我使用的代码是：

    $RequestUrl     =   "http://demourl";
    $RequestXml =   '<Bookingrequest>
                          <details></details>
                          <key>Rg+0U0MHk4j4XRiFoKIn0f2tg</key>  
                       </Bookingrequest>';                          
    //setting the curl parameters.
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, $RequestUrl);
    curl_setopt($ch, CURLOPT_POST, true );
    // Passing parameters as xml
    curl_setopt($ch, CURLOPT_POSTFIELDS,"xmlRequest=" . $RequestXml);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 300);
    $data = curl_exec($ch);
    curl_close($ch);