调用微信支付的API接口验证

public function check_wx() {
        $mch_id = '1234567891'; // 商户号
        $key = 'rKVuqAv2zlum1JQkfR7OSeRHc1Bg7poD'; // 商户支付密钥
        $nonce_str = strtoupper(md5('3123123131')); // 随机字符串

        // 开始生成sign
        $str = "mch_id=".$mch_id."&nonce_str=".$nonce_str."&key=".$key;
        $sign = strtoupper(md5( $str ));


        // 打印字符串和签名
        echo $nonce_str;
        echo "<br />";
        echo $sign;


        $xml = "<xml>
                  <mch_id>1495281252</mch_id>
                  <nonce_str>4E74A5EC8F10C3E7EECE6D8D574CB861</nonce_str>
                  <sign>BFB9329EC7B027DF83AFB848F08E8077</sign>
                </xml>";
        $url = "https://apitest.mch.weixin.qq.com/sandboxnew/pay/getsignkey";
        /*$a = &#39;{"mch_id":"1495281252","nonce_str":"4E74A5EC8F10C3E7EECE6D8D574CB861","sign":"BFB9329EC7B027DF83AFB848F08E8077"}&#39;;*/
        // $result = http_request($url,$xml);
        $result = $this->postXmlCurl($xml,$url);
        dump($result);




    }
    /**
     *  作用：以post方式提交xml到对应的接口url
     */
    public function postXmlCurl($xml,$url,$second=30)
    {       
        //初始化curl        
        $ch = curl_init();
        //设置超时  CURLOP_TIMEOUT
        //curl_setopt($ch, CURLOP_TIMEOUT, $second);
        curl_setopt($ch, CURLOPT_TIMEOUT, $second);
        //这里设置代理，如果有的话
        //curl_setopt($ch,CURLOPT_PROXY, &#39;8.8.8.8&#39;);
        //curl_setopt($ch,CURLOPT_PROXYPORT, 8080);
        curl_setopt($ch,CURLOPT_URL, $url);
        curl_setopt($ch,CURLOPT_SSL_VERIFYPEER,FALSE);
        curl_setopt($ch,CURLOPT_SSL_VERIFYHOST,FALSE);
        //设置header
        curl_setopt($ch, CURLOPT_HEADER, FALSE);
        //要求结果为字符串且输出到屏幕上
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);
        //post提交方式
        curl_setopt($ch, CURLOPT_POST, TRUE);
        curl_setopt($ch, CURLOPT_POSTFIELDS, $xml);
        //运行curl
        $data = curl_exec($ch);
        //curl_close($ch);
        //返回结果
        if($data)
        {
            curl_close($ch);
            return $data;
        }
        else 
        { 
            $error = curl_errno($ch);
            //echo "curl出错，错误码:$error"."<br>"; 
            //echo "<a href=&#39;http://curl.haxx.se/libcurl/c/libcurl-errors.html&#39;>错误原因查询</a></br>";
            curl_close($ch);
            return false;
        }
    }