擺脫CA2202

Question

如何擺脫CA2202警告（CA2202：Microsoft.Usage：Object'compressedStream'可以在方法'Compression.InternalDecompress（byte []）'中多次拋棄。爲避免生成System.ObjectDisposedException你不應該調用從下面的代碼處置的對象上一次以上）：

 using (var compressedStream = new MemoryStream(inputData)) 
     using (var zipStream = new GZipStream(compressedStream, CompressionMode.Decompress)) 
     using (var resultStream = new MemoryStream()) 
     { 
      zipStream.CopyTo(resultStream); 
      return resultStream.ToArray(); 
     } 

我試圖擺脫的「使用」的聲明，並使用try /終於模式取代它，但後來我的獲取CA2000（CA2000：Microsoft.Reliability：在'Compression.InternalDecompress（byte []）'方法中，在對所有引用超出範圍之前調用System.IDisposable.Dispose對象的'stream'）。我曾嘗試更換這樣上面的代碼：

 MemoryStream decompressedData = null; 
     MemoryStream stream = null; 
     GZipStream decompressor = null; 
     try 
     { 
      decompressedData = new MemoryStream(); 
      stream = new MemoryStream(inputData); 
      decompressor = new GZipStream(stream, CompressionMode.Decompress, false); 
      stream = null; 

      int bytesRead = 1; 
      int chunkSize = 4096; 
      byte[] chunk = new byte[chunkSize]; 

      while ((bytesRead = decompressor.Read(chunk, 0, chunkSize)) > 0) 
      { 
       decompressedData.Write(chunk, 0, bytesRead); 
      } 

      decompressor = null; 

      return decompressedData.ToArray(); 
     } 
     finally 
     { 
      if (stream != null) 
      { 
       stream.Dispose(); 
      } 

      if (decompressor != null) 
      { 
       decompressor.Dispose(); 
      } 

      if (decompressedData != null) 
      { 
       decompressedData.Dispose(); 
      } 
     } 

Answer 1

這是我使用：

public class Compression 
{ 
    public Compression() 
    { 

    } 

    public byte[] Compress(byte[] buffer) 
    { 
     byte[] gzBuffer; 

     using (MemoryStream ms = new MemoryStream()) 
     { 
      using (GZipStream zip = new GZipStream(ms, CompressionMode.Compress, true)) 
      { 
       zip.Write(buffer, 0, buffer.Length); 
       zip.Close(); 
      } 
      ms.Position = 0; 

      MemoryStream outStream = new MemoryStream(); 

      byte[] compressed = new byte[ms.Length]; 
      ms.Read(compressed, 0, compressed.Length); 

      gzBuffer = new byte[compressed.Length + 4]; 
      Buffer.BlockCopy(compressed, 0, gzBuffer, 4, compressed.Length); 
      Buffer.BlockCopy(BitConverter.GetBytes(buffer.Length), 0, gzBuffer, 0, 4); 
     } 

     return gzBuffer; 
    } 

    public byte[] Decompress(byte[] gzBuffer) 
    { 
     byte[] buffer; 

     using (MemoryStream ms = new MemoryStream()) 
     { 
      int msgLength = BitConverter.ToInt32(gzBuffer, 0); 
      ms.Write(gzBuffer, 4, gzBuffer.Length - 4); 

      buffer = new byte[msgLength]; 

      ms.Position = 0; 
      using (GZipStream zip = new GZipStream(ms, CompressionMode.Decompress)) 
      { 
       zip.Read(buffer, 0, buffer.Length); 
      } 
     } 

     return buffer; 
    } 
} 

或者你可以添加一個編譯語句類

#pragma warning disable 2202 

namespace Your.Namespace 
{ 
... 
} 

#pragma warning restore 2202 

Answer 2

這是我結束了什麼 - 擺脫了CA2000和CA2202：

private static MemoryStream GetMemoryStream() 
    { 
     return new MemoryStream(); 
    } 

    private static byte[] InternalDecompress(byte[] inputData) 
    { 
     Debug.Assert(inputData != null, "inputData cannot be null"); 

     MemoryStream decompressedData = GetMemoryStream(); 
     MemoryStream inputDataMemoryStream = GetMemoryStream(); 

     GZipStream decompressor = null; 

     try 
     { 
      inputDataMemoryStream.Write(inputData, 0, inputData.Length); 
      inputDataMemoryStream.Position = 0; 

      decompressor = new GZipStream(inputDataMemoryStream, CompressionMode.Decompress, false); 

      int bytesRead; 
      int chunkSize = 4096; 
      byte[] chunk = new byte[chunkSize]; 

      while ((bytesRead = decompressor.Read(chunk, 0, chunkSize)) > 0) 
      { 
       decompressedData.Write(chunk, 0, bytesRead); 
      } 
     } 
     finally 
     { 
      if (decompressor != null) 
      { 
       decompressor.Dispose(); 
      } 
     } 

     return decompressedData.ToArray(); 
    } 

Answer 3

這是我的嘗試。它的工作原理，它避免了CA2202

/// <summary> 
    /// Compresses byte array to new byte array. 
    /// </summary> 
    public byte[] Compress(byte[] raw) 
    { 
     MemoryStream outStream = null; 
     GZipStream tinyStream = null; 
     byte[] retValue = null; 
     try 
     { 
      outStream = new MemoryStream(); 
      tinyStream = new GZipStream(outStream, CompressionMode.Compress); 
      using (var mStream = new MemoryStream(raw)) 
       mStream.CopyTo(tinyStream); 
     } 
     finally 
     { 
      if (tinyStream != null) 
      { 
       tinyStream.Dispose(); 
       retValue = outStream.ToArray(); 
      } 
      else if (outStream != null) 
      { 
       retValue = outStream.ToArray(); 
       outStream.Dispose(); 
      } 
     } 
     return retValue; 
    } 

[CA2202，如何解決這種情況下]的