“System.Net.HttpWebRequest"不包含“GetRequestStream"的定义 [英] 'System.Net.HttpWebRequest' does not contain a definition for 'GetRequestStream'

问题描述

我是 C# 和 Windows 手机的新手，正在尝试制作一个执行 JSON 请求的小应用程序.我正在遵循这篇文章中的示例 https://stackoverflow.com/a/4988809/702638

I am new to both C# and Windows phone and am trying to make a small app that performs a JSON request. I am following the example in this post https://stackoverflow.com/a/4988809/702638

我当前的代码是这样的:

My current code is this:

public string login()
{
    var httpWebRequest = (HttpWebRequest)WebRequest.Create(MY_URL);
    httpWebRequest.ContentType = "text/plain"; 
    httpWebRequest.Method      = "POST";

    using (var streamWriter = new StreamWriter(httpWebRequest.GetRequestStream()))
    {
       string text = MY_JSON_STRING;
       streamWriter.Write(text);
    }
}

但出于某种原因，Visual Studio 正在标记 GetRequestStream() 并显示一条错误消息:

but for some reason Visual Studio is flagging GetRequestStream() with an error message:

错误 CS1061:System.Net.HttpWebRequest"不包含'GetRequestStream' 的定义并且没有扩展方法'GetRequestStream' 接受类型的第一个参数可以找到System.Net.HttpWebRequest"(您是否缺少使用指令或程序集引用?)

error CS1061: 'System.Net.HttpWebRequest' does not contain a definition for 'GetRequestStream' and no extension method 'GetRequestStream' accepting a first argument of type 'System.Net.HttpWebRequest' could be found (are you missing a using directive or an assembly reference?)

关于为什么会发生这种情况的任何想法?我已经导入了 System.Net 包.

Any thoughts on why this would be happening? I have already imported the System.Net package.

推荐答案

HttpWebRequest 在 WP8 中没有 GetRequestStream 或 GetRequestStreamAsync.最好的办法是创建一个任务并等待它，如下所示:

HttpWebRequest doesn't have a GetRequestStream or GetRequestStreamAsync in WP8. Your best bet is to create a Task and await on it, like so:

using (var stream = await Task.Factory.FromAsync<Stream>(request.BeginGetRequestStream, request.EndGetRequestStream, null))
{
    // ...
}

正如您所提到的，您是 C# 新手，您需要将登录方法设为异步才能使用 await 关键字:

as you've mentioned that you're new to C#, you would need to have your login method be async to use the await keyword:

public async Task<string> LoginAsync()
{
    // ...
}

登录的调用者在调用时需要使用 await 关键字:

Callers to login would need to use the await keyword when calling:

string result = await foo.LoginAsync();

这里有关于这个主题的很好的入门:http://msdn.microsoft.com/en-us/library/vstudio/hh191443.aspx

Here's a good primer on the subject: http://msdn.microsoft.com/en-us/library/vstudio/hh191443.aspx

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