在 C# 中下载之前获取二进制文件的名称
首先让我描述一下情况。 我的 C# 应用程序向 PHP 服务器请求最新更新。它使用它的 URL 和一个简单的 POST 属性，例如：127.0.0.1/update.php?ver=0.2，如果没有版本低于 0.2，则服务器响应 404，如果有更新版本，则服务器响应 200 OK，并开始发送二进制文件在 mime 类型中：八位字节流。
我在获取此文件时没有任何问题，但在获取其文件名时遇到问题。
使用此代码：
WebClient webClient = new WebClient();
webClient.DownloadFile("http://127.0.0.1/update.php?ver=0.2", filename);
我必须输入我的文件名，但是如果我希望它与服务器上的文件具有相同的名称怎么办？下载之前如何获取它？
At first let me describe the situation.
My application in C# asks the PHP server for the newest update. It uses its URL and a simple POST attributes like: 127.0.0.1/update.php?ver=0.2, the server responds with 404 if there's no never version than 0.2 and with 200 OK when there's a newer version and starts sending the binary file in mime-type: octet-stream.
I don't have any problems with getting this file, but I'm having problems with getting its filename.
With this code:
WebClient webClient = new WebClient();
webClient.DownloadFile("http://127.0.0.1/update.php?ver=0.2", filename);
I have to put my filename but what if I want it to have THE SAME NAME as the file on server? How can I get it before downloading it?
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如果您使用
OpenRead()那么您可以查看webClient.ResponseHeaders["content-disposition"]是否有值并解析出 filename="blah.blah"部分。然而，网络上的绝大多数流没有文件名信息，当发送时，您可能需要根据内容类型重写文件扩展名，以便文件扩展名与所在计算机上的映射相匹配正在保存到。
If you use
OpenRead()then you can see if there's a value forwebClient.ResponseHeaders["content-disposition"]and parse out the filename="blah.blah" part.However the vast majority of streams on the web don't have filename information, and when it is sent you may want to re-write the file extension based on the content-type so that the file extension matches the mapping on the machine it is being save to.
这不可能直接实现，因为
WebClient提供的高级功能不太适合此类场景。您可以采取多种方法，但它们都需要一种或另一种类型的更改。这里有几个：
DownloadString），告诉您是否有更新及其名称，然后 调用DownloadFile来获取更新本身，并知道名称。DownloadFile的便利，在较低层处理HTTP请求；这样做，以便您能够读取 HTTP 响应标头，并添加一个标头（可以是任何内容，您甚至可以像X-Save-Filename:一样编写一个标头）来告诉您什么文件名应该是.This is not directly possible because
WebClientoffers high-level functionality that doesn't lend itself too well to such scenarios.There are several approaches that you could take, but they all require changes of one type or other. Here are a couple:
DownloadString) that tells you if there is an update and what its name is, then callDownloadFileto get the update itself, knowing the name.DownloadFileand handle the HTTP request at a lower level; do this so that you will be able to read the HTTP response headers, and add a header (can be anything, you can even make one up like e.g.X-Save-Filename:) that tells you what the filename should be.