C# 试图通过C编写文件下载的Web服务器端实现，其中消息体是文件内容

我的问题/挑战非常类似于几个不同的堆栈溢出帖子，但我已经详细阅读了它们，并且仍然在努力让最基本的应用程序正常工作。具体地说，我相信并且都非常接近我想要实现的目标

为了给您提供上下文，我正在尝试编写/存根一个简单的固件OTA（无线）服务器。我最初的目标似乎很简单，但我花了很多时间，几乎没有任何进展。我想提供一个可以从浏览器（以及最终在IoT设备上运行的一些固件）点击的URL，该URL将接收一些参数（通过URL参数或通过标题）。如果固件更新可用，则调用应返回一个文件作为响应主体；如果当前没有可用的更新，则调用应返回一个合适的HTTP响应代码（或仅返回一个空消息主体）

我在VisualStudio的网站应用程序方面不是很有经验，但在C#方面却很舒服，而且它似乎是一个很好的环境，可以让它快速运行。我对其他实现持开放态度，但我认为编写控制器是最简单的方法。我了解到，这个Web API似乎主要用于.Net到.Net的通信，所以如果有更好的平台，我很高兴被指向更好的方向。以下是我总结的内容（充分利用了上面的链接，因此没有我的功劳！）：

}

当我输入URL

http://localhost:2265/api/ota

，我在屏幕上看到以下原始输出：

{"version":{"major":1,"minor":1,"build":-1,"revision":-1,"majorRevision":-1,"minorRevision":-1},"content":{"headers":[{"key":"Content-Disposition","value":["attachment; filename=hello-world.bin"]},{"key":"Content-Type","value":["application/octet-stream"]},{"key":"Content-Length","value":["407904"]}]},"statusCode":200,"reasonPhrase":"OK","headers":[],"requestMessage":null,"isSuccessStatusCode":true}

在Fiddler2中捕获的整个响应如下所示：

HTTP/1.1200正常

传输编码：分块

内容类型：application/json；字符集=utf-8

服务器：红隼

X-SourceFiles:=？UTF-8？B？YzpcdXNlcnNcZG91Z2NcZG9jdW1lbnRzXHZpc3VhbCBzdHVkaW8gMjAxNVxQcm9qZWN0c1xPdmVyVGhl QWLYQXBXHNYY1XPDMVYVGHLQWLYQXBPXGFWAVxVDGE=？=

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日期：2017年2月28日星期二16:43:01 GMT

192

{version:

{“major”：1，“minor”：1，“build”：-1，“revision”：-1，“minorRevision”：-1}，“content”：{“headers”：[{“key”：“content Disposition”，“value”：[“attachment；filename=hello world.bin”]}，{“content Type”，“value”：[“application/octet stream”]}，{“key”：“content Length”，“value”：[“407904”}]，“statusCode”：200，“reasonPhrase”：“OK”，“headers”：[]，“requestMessage”：null，“isSuccessStatusCode”：true}

0

（如果格式有点难看，很抱歉，我想我还需要一些使用MD进行HTTP响应的教程！）

再一次，我的目标是编写C#代码，返回一个HTTP响应，其中头表示文件是附件，消息体只是文件本身

再次感谢您可能提供的任何帮助/见解

---

谢谢-道格。

这是我向浏览器发送文件的标准方法。该方法包含两个参数，一个是文件内容，另一个是客户端将接收的默认文件名。请欣赏

    /// <summary>
    /// Sends the fileData to the browser and prompts the visitor to save it with the 
    /// name specified in fileName.
    /// </summary>
    /// <param name="defaultFilename">File name to use when browser prompts visitor (spaces will be replaced with dashes)</param>
    /// <param name="data">Data to be sent to visitor's browser</param>
    /// <param name="errorMsg"></param>
    // Mod 08/04/09 Ron C - Reworked code to work right in modern browsers.
    public static bool DownloadToBrowser(string data, string defaultFilename, out string errorMsg){
        errorMsg = "";
        System.Web.HttpResponse response = HttpContext.Current.Response;

        try {
            defaultFilename = defaultFilename.Replace(' ', '-');        //firefox will cut the name off at the space if there is one, so get rid of 'em
            response.Clear();
            response.ContentType = "application/octet-stream";
            response.AddHeader("Content-Disposition", "attachment; filename=" + defaultFilename);
            //8/5/09 Adding a "Content-Length" header was cutting off part of my file.  Apparently
            //       it would need to factor in the length of the headers as well as the conent.
            //       since I have no easy way to figure out the length of the headers, initially I was gonna
            //       eliminate "Content-Length" header.  Doing so works great in IE 7 and FireFox 3, but not 
            //       in Safari 3 or 4(which doesn't download the file without the "Content-Length" header.  So I
            //       resorted to a cludge of using the header tag and setting it to content length + 1000 for headers.
            //       I'd love to have a better solution, but his one works and I've already wasted 6+ hours to get to this
            //       solution.  Cross broswer downloading of a file shouldn't have to be so hard.  -Ron
            int len = data.Length + 1000;
            response.AddHeader("Content-Length", len.ToString()); //file size for progress dialog
            response.Write(data);
            response.Flush();
            response.Close();       //Close() needed to prevent html from page being streamed back after the file data we sent.

            //Don't use response.End() cause it throws a thread abort exception that can't be caught! Actually you can
            //catch it but then it rethrows after the catch block! (What bozo thought that up?).  I found lots of threads on this.


        } catch (Exception ex) {
            errorMsg = "Unable to download file to browser.";
            //Add code here to log the error in your environment
            return false;
        }
        return true;
    }

//
///将文件数据发送到浏览器，并提示访问者使用
///文件名中指定的名称。
/// 
///浏览器提示访问者时使用的文件名（空格将替换为破折号）
///要发送到访问者浏览器的数据
/// 
//Mod 08/04/09 Ron C-重新编写的代码在现代浏览器中正常工作。
public static bool DownloadToBrowser（字符串数据、字符串defaultFilename、输出字符串errorMsg）{
errorMsg=“”；
System.Web.HttpResponse response=HttpContext.Current.response；
试一试{
defaultFilename=defaultFilename.Replace（“”，“-”）；//如果有名字，firefox会在空格处删掉它，所以把它们去掉
response.Clear（）；
response.ContentType=“应用程序/八位字节流”；
response.AddHeader（“内容处置”、“附件；文件名=“+defaultFilename”）；
//2009年8月5日添加“内容长度”标题会切断我的部分文件
//它需要考虑头的长度和内容。
//因为我没有简单的方法来计算头球的长度，最初我想
//消除“内容长度”标题。这样做在IE 7和FireFox 3中效果很好，但不是很好
//在Safari3或4中（如果没有“Content Length”头文件，则不会下载文件）
//求助于使用header标记并将其设置为content-length+1000作为标题。
//我很想有一个更好的解决方案，但他的解决方案很有效，我已经浪费了6个多小时来解决这个问题
//解决方案。跨兄弟下载文件不应该这么难。-罗恩
int len=数据长度+1000；
response.AddHeader（“Content Length”，len.ToString（））；//进度对话框的文件大小
响应。写入（数据）；
response.Flush（）；
response.Close（）；//需要Close（）来防止html页面在我们发送的文件数据之后被流回。
//不要使用response.End（），因为它会抛出一个无法捕获的线程中止异常！实际上您可以
//接住它，但它在接住挡块后会重新旋转！（博佐怎么想的？）。我在这上面发现了很多线。
}捕获（例外情况除外）{
errorMsg=“无法将文件下载到浏览器。”；
//在此处添加代码以在您的环境中记录错误
返回false；
}
返回true；
}

Ron先生-感谢您的回复。我感谢您的帮助！您是否建议我将其与我执行的Web Api调用结合使用

    /// <summary>
    /// Sends the fileData to the browser and prompts the visitor to save it with the 
    /// name specified in fileName.
    /// </summary>
    /// <param name="defaultFilename">File name to use when browser prompts visitor (spaces will be replaced with dashes)</param>
    /// <param name="data">Data to be sent to visitor's browser</param>
    /// <param name="errorMsg"></param>
    // Mod 08/04/09 Ron C - Reworked code to work right in modern browsers.
    public static bool DownloadToBrowser(string data, string defaultFilename, out string errorMsg){
        errorMsg = "";
        System.Web.HttpResponse response = HttpContext.Current.Response;

        try {
            defaultFilename = defaultFilename.Replace(' ', '-');        //firefox will cut the name off at the space if there is one, so get rid of 'em
            response.Clear();
            response.ContentType = "application/octet-stream";
            response.AddHeader("Content-Disposition", "attachment; filename=" + defaultFilename);
            //8/5/09 Adding a "Content-Length" header was cutting off part of my file.  Apparently
            //       it would need to factor in the length of the headers as well as the conent.
            //       since I have no easy way to figure out the length of the headers, initially I was gonna
            //       eliminate "Content-Length" header.  Doing so works great in IE 7 and FireFox 3, but not 
            //       in Safari 3 or 4(which doesn't download the file without the "Content-Length" header.  So I
            //       resorted to a cludge of using the header tag and setting it to content length + 1000 for headers.
            //       I'd love to have a better solution, but his one works and I've already wasted 6+ hours to get to this
            //       solution.  Cross broswer downloading of a file shouldn't have to be so hard.  -Ron
            int len = data.Length + 1000;
            response.AddHeader("Content-Length", len.ToString()); //file size for progress dialog
            response.Write(data);
            response.Flush();
            response.Close();       //Close() needed to prevent html from page being streamed back after the file data we sent.

            //Don't use response.End() cause it throws a thread abort exception that can't be caught! Actually you can
            //catch it but then it rethrows after the catch block! (What bozo thought that up?).  I found lots of threads on this.


        } catch (Exception ex) {
            errorMsg = "Unable to download file to browser.";
            //Add code here to log the error in your environment
            return false;
        }
        return true;
    }