php圖片下載鏈接不起作用

Question

我已經嘗試使用下面的代碼下載圖像，但是它可以在我的計算機上的localhost中運行，但是當站點駐留在托管服務上時，則當我單擊下載鏈接時會顯示一條消息
標頭已發送

無法下載圖片。請給我解決。

鏈接使用：

print'<p><a href="?u=download&file=nplace_image/'. $rs[$i][16].'" class="btn"><i class="icon-cloud-download"></i> Download</a></p>';

我的代碼：

<?php

$file = $_GET['file'];

download_file($file);

function download_file( $fullPath ){

  // Must be fresh start
  if( headers_sent() )
    die('Headers Sent');

  // Required for some browsers
  if(ini_get('zlib.output_compression'))
    ini_set('zlib.output_compression', 'Off');

  // File Exists?
  if( file_exists($fullPath) ){

    // Parse Info / Get Extension
    $fsize = filesize($fullPath);
    $path_parts = pathinfo($fullPath);
    $ext = strtolower($path_parts["extension"]);

    // Determine Content Type
    switch ($ext) {
      case "pdf": $ctype="application/pdf"; break;
      case "exe": $ctype="application/octet-stream"; break;
      case "zip": $ctype="application/zip"; break;
      case "doc": $ctype="application/msword"; break;
      case "xls": $ctype="application/vnd.ms-excel"; break;
      case "ppt": $ctype="application/vnd.ms-powerpoint"; break;
      case "gif": $ctype="image/gif"; break;
      case "png": $ctype="image/png"; break;
      case "jpeg":
      case "jpg": $ctype="image/jpg"; break;
      default: $ctype="application/force-download";
    }

    header("Pragma: public"); // required
    header("Expires: 0");
    header("Cache-Control: must-revalidate, post-check=0, pre-check=0");
    header("Cache-Control: private",false); // required for certain browsers
    header("Content-Type: $ctype");
    header("Content-Disposition: attachment; filename=\"".basename($fullPath)."\";" );
    header("Content-Transfer-Encoding: binary");
    header("Content-Length: ".$fsize);
    ob_clean();
    flush();
    readfile( $fullPath );

  } else
    die('File Not Found');

}
?>

Answer 1

在執行下載代碼之前，似乎已輸出某些內容。 因此它顯示此消息。 您可以檢查服務器是否在錯誤日志文件中記錄了任何內容。 另外，您可以在調用download_file函數之前嘗試使用ob_clean。

Answer 2

使用以下代碼：

    <?php
    if(isset($_GET['file'])) {
    $file = isset($_GET['file'])?$_GET['file']:'';

    download_file($file);
    }

    function download_file( $fullPath ){

      // Must be fresh start
      if( headers_sent() )
        die('Headers Sent');

      // Required for some browsers
      if(ini_get('zlib.output_compression'))
        ini_set('zlib.output_compression', 'Off');

      // File Exists?
      if( file_exists($fullPath) ){

        // Parse Info / Get Extension
        $fsize = filesize($fullPath);
        $path_parts = pathinfo($fullPath);
        $ext = strtolower($path_parts["extension"]);

        // Determine Content Type
        switch ($ext) {
          case "pdf": $ctype="application/pdf"; break;
          case "exe": $ctype="application/octet-stream"; break;
          case "zip": $ctype="application/zip"; break;
          case "doc": $ctype="application/msword"; break;
          case "xls": $ctype="application/vnd.ms-excel"; break;
          case "ppt": $ctype="application/vnd.ms-powerpoint"; break;
          case "gif": $ctype="image/gif"; break;
          case "png": $ctype="image/png"; break;
          case "jpeg":
          case "jpg": $ctype="image/jpg"; break;
          default: $ctype="application/force-download";
        }

        header("Pragma: public"); // required
        header("Expires: 0");
        header("Cache-Control: must-revalidate, post-check=0, pre-check=0");
        header("Cache-Control: private",false); // required for certain browsers
        header("Content-Type: $ctype");
        header("Content-Disposition: attachment; filename=\"".basename($fullPath)."\";" );
        header("Content-Transfer-Encoding: binary");
        header("Content-Length: ".$fsize);
        ob_clean();
        flush();
        readfile( $fullPath );

} else
    die('File Not Found');

}
?>

    <?php print'<p><a href="?u=download&file=noteII007.jpg" class="btn"><i class="icon-cloud-   download"></i> Download</a></p>';?>