GZipStream被切斷XML

Question

的最後一部分，我創建了一個叫做AddGZip擴展方法，看起來像以下：

public static void AddGZip(this HttpResponse response) 
{ 
    response.Filter = new GZipStream(response.Filter, CompressionMode.Compress); 
    response.AppendHeader("Content-Encoding", "gzip"); 
} 

這是代碼的一個非常削減版本：

var response = HttpContext.Current.Response; 
var request = HttpContext.Current.Request; 
var result = File.ReadAllText(path); 
if (request.SupportsGZip) 
{ 
    response.AddGZip(); 
} 
response.Write(result); 
response.Flush(); 

當您在支持GZip的Web瀏覽器中查看響應時，您會看到如下錯誤：

"XML Parsing Error: unclosed token Location: http://webserver1/1234.xml Line Number 78, Column 1:"

Wh我查看源代碼，它基本上錯過了XML文件末尾的最後一個>。所以1或2個字節。

如果我註釋掉AddGZip線，它工作正常。但是我真的想要支持GZip，因爲XML可能非常大。

有人對我有什麼建議嗎？我試過檢查很多博客，但沒有解決方案似乎在這種類型的錯誤。

Dave

Answer 1

有一個問題（或者可能是一個很聰明的功能，我還沒有看到任何地方合理）與DeflateStream（GZipStream基礎上DeflateStream和繼承問題*），其中沖洗可能會丟失數據。

Response.Flush()將沖洗過濾器。該解決方案是使用的包裝是知道壓縮和基礎下沉兩者，並且僅僅刷新了後者：

public enum CompressionType 
{ 
    Deflate, 
    GZip 
} 
/// <summary> 
/// Provides GZip or Deflate compression, with further handling for the fact that 
/// .NETs GZip and Deflate filters don't play nicely with chunked encoding (when 
/// Response.Flush() is called or buffering is off. 
/// </summary> 
public class WebCompressionFilter : Stream 
{ 
    private Stream _compSink; 
    private Stream _finalSink; 
    public WebCompressionFilter(Stream stm, CompressionType comp) 
    { 
     switch(comp) 
     { 
      case CompressionType.Deflate: 
       _compSink = new DeflateStream((_finalSink = stm), CompressionMode.Compress); 
       break; 
      case CompressionType.GZip: 
       _compSink = new GZipStream((_finalSink = stm), CompressionMode.Compress); 
       break; 
     } 
    } 
    public override bool CanRead 
    { 
     get 
     { 
      return false; 
     } 
    } 
    public override bool CanSeek 
    { 
     get 
     { 
      return false; 
     } 
    } 
    public override bool CanWrite 
    { 
     get 
     { 
      return true; 
     } 
    } 
    public override long Length 
    { 
     get 
     { 
      throw new NotSupportedException(); 
     } 
    } 
    public override long Position 
    { 
     get 
     { 
      throw new NotSupportedException(); 
     } 
     set 
     { 
      throw new NotSupportedException(); 
     } 
    } 
    public override void Flush() 
    { 
     //We do not flush the compression stream. At best this does nothing, at worse it 
     //loses a few bytes. We do however flush the underlying stream to send bytes down the 
     //wire. 
     _finalSink.Flush(); 
    } 
    public override long Seek(long offset, SeekOrigin origin) 
    { 
     throw new NotSupportedException(); 
    } 
    public override void SetLength(long value) 
    { 
     throw new NotSupportedException(); 
    } 
    public override int Read(byte[] buffer, int offset, int count) 
    { 
     throw new NotSupportedException(); 
    } 
    public override void Write(byte[] buffer, int offset, int count) 
    { 
     _compSink.Write(buffer, offset, count); 
    } 
    public override void WriteByte(byte value) 
    { 
     _compSink.WriteByte(value); 
    } 
    public override void Close() 
    { 
     _compSink.Close(); 
     _finalSink.Close(); 
     base.Close(); 
    } 
    protected override void Dispose(bool disposing) 
    { 
     if(disposing) 
     { 
      _compSink.Dispose(); 
      _finalSink.Dispose(); 
     } 
     base.Dispose(disposing); 
    } 
} 

另外值得一提的是，該支持gzip編碼大多數用戶代理還支持deflate-編碼。雖然deflate的大小改進可以忽略不計（幾字節），但某些體系結構上的某些庫會更好地處理deflate（這適用於壓縮和解壓縮），所以始終值得使用HTTP壓縮來優化gzip的壓縮。

Answer 2

您是否嘗試過通過IIS添加gzip？有關於它的question，所以看看它是什麼。基本上，IIS會進行所有壓縮，因此您不必這樣做。