[Azure][WebSites] 在WebSite上使用HttpModule取得Response Length

其實絕大多數一般的網站都可以直接搬上Azure Website，不過最近剛好有客戶需要，因此還是寫起來。

• 首先我們需要一個HttpModule以及一個Custom Response Filter
• 建立一個HttpModule，在Init()中加入以下程式碼

  context.PostRequestHandlerExecute += delegate(object sender, EventArgs e)
  {
     HttpContext httpContext = ((HttpApplication)sender).Context;
     HttpResponse response = httpContext.Response;
     response.Filter = new IWantMyResponseLengthStream(response.Filter);
  }

  
  



• 
  
  接著我們需要撰寫一個IWantMyResponseLengthStream類別，繼承自MemoryStream
  
  
  

      public class IWantMyResponseLengthStream: MemoryStream
      {
          private readonly Stream responseStream;
          private long responseLen = 0;
          public override long Length
          {
              get
              {
                  return responseLen ;
              }
          }
          public IWantMyResponseLengthStream(Stream responseStream)
          {
              this.responseStream = responseStream;
          }
  
          public override void Write(byte[] buffer, int offset, int count)
          {
              this.responseLen += count;
              this.responseStream.Write(buffer, offset, count);
          }
  
          public override void Flush()
          {
              //this.Length就是回應的訊息大小了
              //var requestURL = HttpContext.Current.Request.Url.ToString();
              //var remoteIP = HttpContext.Current.Request.UserHostAddress;
              base.Flush();
          }
      }

  
  



• 
  
  接著確認我們的Azure Website服務的pipeline模式是Classic還是Integrated；在WebSite->Configure->Managed Pipeline Mode
  
  



• 
  
  根據不同的Pipeline Mode，修改web.config
  
  



• 
  
  然後佈署到Azure WebSite上就可以了。