我正在尝试获取 HttpResponseMessage 的内容。它应该是：{"message":"Action '' does not exist!","success":false}，但我不知道如何从 HttpResponseMessage 中获取它。

HttpClient httpClient = new HttpClient();
HttpResponseMessage response = await httpClient.GetAsync("http://****?action=");
txtBlock.Text = Convert.ToString(response); //wrong!

在这种情况下 txtBlock 将具有价值：

StatusCode: 200, ReasonPhrase: 'OK', Version: 1.1, Content: System.Net.Http.StreamContent, Headers:
{
  Vary: Accept-Encoding
  Keep-Alive: timeout=15, max=100
  Connection: Keep-Alive
  Date: Wed, 10 Apr 2013 20:46:37 GMT
  Server: Apache/2.2.16
  Server: (Debian)
  X-Powered-By: PHP/5.3.3-7+squeeze14
  Content-Length: 55
  Content-Type: text/html
}