HttpWebRequest错误：503服务器不可用

Question

我正在使用HttpWebRequest，并且在执行GetResponse（）时出现错误。

我使用此代码：

private void button1_Click(object sender, EventArgs e) 
    { 
     Uri myUri = new Uri("http://www.google.com/sorry/?continue=http://www.google.com/search%3Fq%3Dyamaha"); 
     // Create a 'HttpWebRequest' object for the specified url. 
     HttpWebRequest myHttpWebRequest = (HttpWebRequest)WebRequest.Create(myUri); 
     // Set the user agent as if we were a web browser 
     myHttpWebRequest.UserAgent = @"Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.0.4) Gecko/20060508 Firefox/1.5.0.4"; 

     HttpWebResponse myHttpWebResponse = (HttpWebResponse)myHttpWebRequest.GetResponse(); 
     var stream = myHttpWebResponse.GetResponseStream(); 
     var reader = new StreamReader(stream); 
     var html = reader.ReadToEnd(); 
     // Release resources of response object. 
     myHttpWebResponse.Close(); 

     textBox1.Text = html; 
    } 

Answer 1

服务器确实返回503 HTTP状态代码。但是，它也会返回一个响应主体以及503错误条件（如果您打开该URL，则在浏览器中看到的内容）。

您可以访问异常的Response属性中的响应（如果有503响应，则引发的异常是WebException，它具有Response属性）。你需要抓住这个异常，并具体妥善处理

，你的代码看起来是这样的：

string html; 

try 
{ 
    var myUri = new Uri("http://www.google.com/sorry/?continue=http://www.google.com/search%3Fq%3Dyamaha"); 
    // Create a 'HttpWebRequest' object for the specified url. 
    var myHttpWebRequest = (HttpWebRequest)WebRequest.Create(myUri); 
    // Set the user agent as if we were a web browser 
    myHttpWebRequest.UserAgent = @"Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.0.4) Gecko/20060508 Firefox/1.5.0.4"; 

    var myHttpWebResponse = (HttpWebResponse)myHttpWebRequest.GetResponse(); 
    var stream = myHttpWebResponse.GetResponseStream(); 
    var reader = new StreamReader(stream); 
    html = reader.ReadToEnd(); 
    // Release resources of response object. 
    myHttpWebResponse.Close(); 
} 
catch (WebException ex) 
{ 
    using(var sr = new StreamReader(ex.Response.GetResponseStream())) 
     html = sr.ReadToEnd(); 
} 

textBox1.Text = html;