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一个游离于山间之上的Java爱好者 | A Java lover living in the mountains

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xhr模拟表单下载文件

使用javascript原生XHR下载流文件,可进行计时下载,当然也是可以通过from表单进行下载文件的,但页面可能会有跨域问题,索性就在PHP做个桥接处理了。

一、在页面添加一个按钮

<a href="javascript:;" class="btn btn-xs btn-primary btn-success btn-install" id="exportBtn" data-url="{:url('ajax/downloadExcel')}" >
                            <i class="fa fa-cloud-download"></i> 导出Excel
                        </a>

干嘛有那么麻烦,一个form不就可以解决的事情,非要弄的怎么麻烦呢?原因是下载远程服务器文件,且与本项目不在同一服务器上。

二、xhr模拟表单下载

$('#exportBtn').on('click',function(){

                let url= $(this).data('url') 
                let itime = 0;
                $("#exportBtn").html(`正在下载,耗时<i style="color:red;font-size:16px;font-weight:700;padding: 0 5px;">${itime}</i>秒`);


                let xhr = new XMLHttpRequest();
                xhr.open('get', url, true);
                xhr.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded; charset=UTF-8');
                xhr.responseType = 'blob';

                xhr.send(null);
                xhr.onload = function () {

                    if (this.status == 200) {
                        let blob = this.response;

                        let yLink = document.createElement('a');
                        let myDate = new Date();
                        let nowDateStr=Controller.dateFormat("YYYYmmddHHMMSS", myDate)

                        yLink.style.display = 'none';
                        let contentTypeHeader = xhr.getResponseHeader("Content-Type");
                        // 字符内容转变成blob地址
                        yLink.href = window.URL.createObjectURL(new Blob([blob], { type: contentTypeHeader }));
                        yLink.download = nowDateStr+'.xlsx';;
                        // 触发点击
                        document.body.appendChild(yLink);
                        yLink.click();
                        // 然后移除
                        document.body.removeChild(yLink);

                        clearTimeout(downloadTimer);
                        $("#exportBtn").html("<i class='fa fa-cloud-download'></i> 导出Excel");
                        $("#exportBtn").removeAttr("disabled");

                    }
                }

                let downloadTimer = setInterval(() => {
                    $("#exportExcel").children("i").text(++itime);
                }, 1000);

            })

三、通过PHP CURL 间接性下载流文件

 /**
     * 导出Excel
     */
    public function downloadExcel(){

        $url = 'http://XXX.XXX.XXX.XXX/api/export/excel';
        $temp = [
            'start_time'=>date("Y-m-d H:i:s",time())
        ];

        $stremData = self::getWebFileStream($url,$temp,'post');

        $t=time();
        $today=date("YmdHis",$t);

        $file_name= $today . '.xlsx';

        $excelFile = $_SERVER['DOCUMENT_ROOT']."/excel-file/" . $file_name;

         // 保存文件到指定路径
        $ret=file_put_contents($excelFile,$stremData);

        Log::info('====download方法中====当前系统时间======='.date("Y-m-d H:i:s",time()));
        Log::info('>>>>>>>>>>>>>>>>>>>>>>>>>流文件>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>'.$ret);

        // 释放文件内存
        //unset($stremData);

        self::output_for_download($excelFile, $file_name);
    }

      /**
     * 获取网络接口里面的文件流
     **/
    protected function  getWebFileStream($url,$params,$type){
        $stream = "";
        if(!isset($url) || empty($url))
        return "";
        $ch=curl_init();
        if($type === "post"){
            $temp = json_encode($params);
            curl_setopt_array($ch,[
                CURLOPT_URL              => $url,
                CURLOPT_RETURNTRANSFER   => 1,
                CURLOPT_POST             => 1,
                CURLOPT_HEADER           => 0,
                CURLOPT_POSTFIELDS       => $temp
            ]);

            curl_setopt($ch, CURLOPT_HTTPHEADER, array(
                'Content-Type: application/json',
                'Content-Length: ' . strlen($temp))
            );

        }else{
            curl_setopt_array($ch,[
                CURLOPT_URL              => $url,
                CURLOPT_RETURNTRANSFER   => 1,
                CURLOPT_HEADER           => 0
            ]);
        }
        //输出结果
        $stream = curl_exec($ch);
        //推断curl请求是否超时
        if(curl_errno($ch)){
            $stream = file_get_contents($url);
        }
        //关闭
        curl_close($ch); 
        return $stream;
    }

    /**
     * 将文件输出到浏览器页面
     */
    function output_for_download($filename, $title){

        $fp = fopen($filename,"r");
        header("Content-type: application/vnd.ms-excel;charset=gb2312");
        header("Accept-Length: ".filesize($filename));
        header("Content-Transfer-Encoding: binary");
        header('Content-Disposition: attachment; filename="'.basename($filename).'"');
        // 输出文件内容
        while(!feof($fp)) {
            echo fread($fp,filesize($filename));
        }
        fclose($fp);

        unlink($filename);  //删除文件
        exit;
    }