Question

好的，我们有一个PHP脚本，可以从文件创建下载链接，我们想通过C＃下载该文件。这与进度等工作正常但是当PHP页面出错时，程序会下载错误页面并将其保存为请求的文件。以下是我们的代码：

PHP代码：

<?php
$path = 'upload/test.rar';

    if (file_exists($path)) {
        $mm_type="application/octet-stream";
        header("Pragma: public");
        header("Expires: 0");
        header("Cache-Control: must-revalidate, post-check=0, pre-check=0");
        header("Cache-Control: public");
        header("Content-Description: File Transfer");
        header("Content-Type: " . $mm_type);
        header("Content-Length: " .(string)(filesize($path)) );
        header('Content-Disposition: attachment; filename="'.basename($path).'"');
        header("Content-Transfer-Encoding: binary\n");
        readfile($path); 
        exit();
    } 
    else {
    print 'Sorry, we could not find requested download file.';
    }
?>

C＃代码：

private void btnDownload_Click(object sender, EventArgs e)
    {
        string url = "http://***.com/download.php";
        WebClient client = new WebClient();
        client.DownloadFileCompleted += new AsyncCompletedEventHandler(client_DownloadFileCompleted);
        client.DownloadProgressChanged += new DownloadProgressChangedEventHandler(ProgressChanged);
        client.DownloadFileAsync(new Uri(url), @"c:\temp\test.rar");
    }

    private void ProgressChanged(object sender, DownloadProgressChangedEventArgs e)
    {
        progressBar.Value = e.ProgressPercentage;
    }

    void client_DownloadFileCompleted(object sender, AsyncCompletedEventArgs e)
    {
            MessageBox.Show(print);
    }

Answer 1

您应该使用PHP记录的here中的Header函数，而不是打印错误消息。

header($_SERVER["SERVER_PROTOCOL"]." 404 Not Found", true, 404);

由于您的异步调用的性质，不会抛出WebException。在您的DownloadFileCompleted回调中，您可以检查

if(e.Error != null)

您的e.Error将包含类似于"The remote server returned an error: (404) Not Found."的行。

Answer 2

您需要通过设置标头通知webclient发生错误，就像您成功下载时一样。我不熟悉PHP，但发现了一个401示例

header('HTTP/1.0 401 Unauthorized', true, 401);

来自here

在C＃中从PHP页面下载文件

2 个答案: