c# - HttpResponseMessage 到字符串

Question

我正在调用一个返回任务的方法，在调用方法中我需要读取字符串形式的响应。

这是我输入的代码:

static public async Task<HttpResponseMessage> Validate(string baseUri,HttpContent content) {
    HttpResponseMessage response = new HttpResponseMessage();   
    response = await client.PostAsync(baseUri,content);    
    return response;
}

public string test(){
    string postJson = "{Login = \"user\", Password =  \"pwd\"}";
    HttpContent stringContent = new StringContent(postJson, 
    UnicodeEncoding.UTF8, "application/json");
    HttpResponseMessage result=Validate(Uri,stringContent);
    var json = result.Content.ReadAsStringAsync().Result;
}

我期望是字符串，但抛出了这个错误:

Cannot implicitly convert type 
'System.Threading.Tasks.Task<System.Net.Http.HttpResponseMessage>' to 
'System.Net.Http.HttpResponseMessage'

Answer 1

您的问题在:

HttpResponseMessage result=Validate(Uri,stringContent);

Validate 正在返回任务，而不是 HttpResponseMessage。

将其更改为:

var result = Validate(Uri,stringContent).Result;

只是稍微清理一下代码并避免使用Result，如果你能负担得起改变它的话:

static public async Task<HttpResponseMessage> Validate(string baseUri, HttpContent content)
{  
   return await client.PostAsync(baseUri,content);
}

public async Task<string> test()
{
   var postJson = "{Login = \"user\", Password =  \"pwd\"}";
   var stringContent = new StringContent(postJson, UnicodeEncoding.UTF8, "application/json");
   var result = await Validate(Uri,stringContent);
   return await result.Content.ReadAsStringAsync();
}

与您的编码风格保持一致。至于为什么调用 .Result 是错误的，正如人们在评论中指出的那样，查看 this blog .