PHP 下载文件

                $file_path = "/xxx/xxx/xx.jpg";
                if(!file_exists($file_path)){
                    //此处为日志记录和错误提示返回信息.逻辑根据自己的情况处理
                    $this->i("未找到图片:{$file_path}");
                    $this->returnError(333, "the files is not found");
                    exit;
                }else{
                    $fp = fopen($file_path, "r+");
                    $file_size = filesize($file_path);
                    //返回的文件
                    Header("Content-type: application/octet-stream");
                    //按照字节格式返回
                    Header("Accept-Ranges: bytes");
                    //返回文件大小
                    Header("Accept-Length: ".$file_size);
                    //弹出客户端对话框，对应的文件名
                    Header("Content-Disposition: attachment; filename=".$name);
                    //分段读取
                    $buffer = 1024 << 2;
                    while(!feof($fp)){
                        $file_data = fread($fp, $buffer);
                        echo $file_data;
                        flush();
                    }
                    //关闭文件
                    fclose($fp);
                    exit;
                }