.net中使用GZipStream进行Gzip压缩的问题

如下两个方法~ 一个压缩，一个解压缩。 都是直接调用 System.IO.Compression.GZipStream 类。

压缩正常，可是解压缩的方法确莫名奇妙的出错。

 1public void Compress(System.IO.Stream orgStream, System.IO.Stream cmpStream)
 2        {
 3            System.IO.Compression.GZipStream zipStream = new System.IO.Compression.GZipStream(cmpStream, System.IO.Compression.CompressionMode.Compress);
 4
 5            byte[] buffer = new byte[100];
 6            int offset = 0;
 7            while (true)
 8            {
 9                int bytesRead = orgStream.Read(buffer, offset, 100);
10                if (bytesRead == 0)
11                {
12                    break;
13                }
14                zipStream.Write(buffer, 0, bytesRead);
15            }
16        }

 

 

 1        public void DeCompress(System.IO.Stream cmpStream, System.IO.Stream orgStream)
 2        {
 3            System.IO.Compression.GZipStream zipStream = new System.IO.Compression.GZipStream(cmpStream, System.IO.Compression.CompressionMode.Decompress);
 4            byte[] buffer = new byte[100];
 5            int offset = 0;
 6            while (true)
 7            {   //cmpStream明明有数据，但是这里个bytesRead第一次循环有时会为0，造成解压缩失败，有时又可以。怎么回事？？？？？
 8                int bytesRead = zipStream.Read(buffer, offset, 100);
 9                if (bytesRead == 0)
10                {
11                    break;
12                }
13                orgStream.Write(buffer, 0, bytesRead);
14            }
15        }

 

不知道是不是System.IO.Compression.GZipStream的使用方法不对，求助园子里的朋友.

====================================================

补充一下修改后的完整代码，这个问题还是没解决，怀疑是GzipStream本身有Bug，发布出来希望有同样遇到问题的朋友能提点一下~

 

 1 //压缩
 2         public void Compress(System.IO.Stream orgStream, System.IO.Stream cmpStream)
 3         {
 4             System.IO.Compression.GZipStream zipStream = new System.IO.Compression.GZipStream(cmpStream, System.IO.Compression.CompressionMode.Compress);
 5             BinaryWriter writer = new BinaryWriter(zipStream);
 6             BinaryReader reader = new BinaryReader(orgStream);
 7             while (true)
 8             {
 9                 byte[] buffer = reader.ReadBytes(100);
10                 if (buffer == null || buffer.Length < 1)
11                     break;
12                 writer.Write(buffer);
13             }
14         }
15 //解压缩
16         public void DeCompress(System.IO.Stream cmpStream, System.IO.Stream orgStream)
17         {
18             System.IO.Compression.GZipStream zipStream = new System.IO.Compression.GZipStream(cmpStream, System.IO.Compression.CompressionMode.Decompress);
19             BinaryReader reader = new BinaryReader(zipStream);
20             BinaryWriter writer = new BinaryWriter(orgStream);
21             while (true)
22             {
23                 byte[] buffer = reader.ReadBytes(100);
24                 if (buffer == null || buffer.Length < 1)
25                     break;
26                 writer.Write(buffer);
27             }
28         }
29 //执行压缩
30         private void button1_Click(object sender, EventArgs e)
31         {
32             System.IO.FileStream targetstream = new System.IO.FileStream(this.txt_SelFile.Text, System.IO.FileMode.Open);
33             System.IO.FileStream saveStream = new System.IO.FileStream(this.txt_SaveTo.Text, System.IO.FileMode.Create, System.IO.FileAccess.Write, System.IO.FileShare.Read);
34             CompressionHelper.Compress(CompressionHelper.CompressionMode.GZip,targetstream, saveStream);
35             targetstream.Close();
36             saveStream.Close();
37         }
38 //执行解压缩
39         private void button2_Click(object sender, EventArgs e)
40         {
41             System.IO.FileStream targetstream = new System.IO.FileStream(this.txt_SelFile.Text, System.IO.FileMode.Open);
42             System.IO.FileStream saveStream = new System.IO.FileStream(this.txt_SaveTo.Text,System.IO.FileMode.Create, System.IO.FileAccess.ReadWrite, System.IO.FileShare.Read);
43             CompressionHelper.DeCompress(CompressionHelper.CompressionMode.GZip , targetstream, saveStream);
44             targetstream.Close();
45             saveStream.Close();
46         }

 

 

 1public static class CompressionHelper
 2    {
 3        public enum CompressionMode
 4        { 
 5            GZip = 0 ,
 6            Deflate = 1
 7        }
 8        public static void Compress(CompressionMode compression, Stream orgStream, Stream cmpStream)
 9        {
10            switch( compression )
11            {
12                case CompressionMode.GZip:
13                    (new GZipCompression()).Compress(orgStream, cmpStream); break;
14                case CompressionMode.Deflate:
15                    (new DeflateCompression()).Compress(orgStream, cmpStream); break;
16            }
17        }
18        public static void DeCompress(CompressionMode compression, Stream cmpStream, Stream orgStream)
19        {
20            switch( compression )
21            {
22                case CompressionMode.GZip:
23                    (new GZipCompression()).DeCompress(cmpStream, orgStream);break;
24                case CompressionMode.Deflate:
25                    (new DeflateCompression()).DeCompress(cmpStream, orgStream);break;
26            }
27        }
28    }

完整的代码附件：/Files/qin0773/Gzip.zip

====================================================================

参考了 http://www.cnblogs.com/dajianshi/archive/2008/03/18/1111180.html 的文章的巴山在回复中提到

“发现GZipStream的Close方法，会调用Dispose方法，直到调FastEncoder.Finish方法，而这方法，里面就一个有微软调试语句说：“only call this when we have no more data to compress!”，对了，就是因为这个方法，给压缩流提供了结束标志，所以在读数据前，必须告诉GZipStream我数据压完了”

然后仔细检查Compress方法 传入基础流，然后包装成zipStream，调用后在Compress的外部对基础流调用了Close，但是没有对包装的GzipStream调用Close方法。赶忙加上。问题解决！修改后的代码如下：

 

 1        public void Compress(System.IO.Stream orgStream, System.IO.Stream cmpStream)
 2        {
 3            System.IO.Compression.GZipStream zipStream = new System.IO.Compression.GZipStream(cmpStream, System.IO.Compression.CompressionMode.Compress);
 4            BinaryWriter writer = new BinaryWriter(zipStream);
 5            BinaryReader reader = new BinaryReader(orgStream);
 6            while (true)
 7            {
 8                byte[] buffer = reader.ReadBytes(1024);
 9                if (buffer == null || buffer.Length < 1)
10                    break;
11                writer.Write(buffer);
12            }
13            writer.Close();
14        }

 

 1        public void DeCompress(System.IO.Stream cmpStream, System.IO.Stream orgStream)
 2        {
 3            System.IO.Compression.GZipStream zipStream = new System.IO.Compression.GZipStream(cmpStream, System.IO.Compression.CompressionMode.Decompress);
 4            BinaryReader reader = new BinaryReader(zipStream);
 5            BinaryWriter writer = new BinaryWriter(orgStream);
 6            while (true)
 7            {
 8                byte[] buffer = reader.ReadBytes(1024);
 9                if (buffer == null || buffer.Length < 1)
10                    break;
11                writer.Write(buffer);
12            }
13            writer.Close();
14        }

 

问题是解决了～ 可是对这个Close方法任有点梗怀。也不应在流关闭后再调用它的Read方法（这里请参见http://www.cnblogs.com/dajianshi/archive/2008/03/18/1111180.html ）应该由一个更好的方法显式的调用来声明压缩完成。