关于2.0里面的解压缩
我目前在做的项目要加入压缩和解压缩
我在MSDN里看到的关于解压缩的内容有一处不明白为什么,请同志们给我个提示
不够再追加
using System;
using System.IO;
using System.IO.Compression;
public class GZipTest
{
public static int ReadAllBytesFromStream(Stream stream, byte[] buffer)
{
// Use this method is used to read all bytes from a stream.
int offset = 0;
int totalCount = 0;
while (true)
{
int bytesRead = stream.Read(buffer, offset, 100);
if ( bytesRead == 0)
{
break;
}
offset += bytesRead;
totalCount += bytesRead;
}
return totalCount;
}
public static bool CompareData(byte[] buf1, int len1, byte[] buf2, int len2)
{
// Use this method to compare data from two different buffers.
if (len1 != len2)
{
Console.WriteLine( "Number of bytes in two buffer are different {0}:{1} ", len1, len2);
return false;
}
for ( int i= 0; i < len1; i++)
{
if ( buf1[i] != buf2[i])
{
Console.WriteLine( "byte {0} is different {1}|{2} ", i, buf1[i], buf2[i]);
return false;
}
}
Console.WriteLine( "All bytes compare. ");
return true;
}
public static void GZipCompressDecompress(string filename)
{
Console.WriteLine( "Test compression and decompression on file {0} ", filename);
FileStream infile;
try
{
// Open the file as a FileStream object.
infile = new FileStream(filename, FileMode.Open, FileAccess.Read, FileShare.Read);
byte[] buffer = new byte[infile.Length];
// Read the file to ensure it is readable.
int count = infile.Read(buffer, 0, buffer.Length);
if ( count != buffer.Length)
{
infile.Close();
Console.WriteLine( "Test Failed: Unable to read data from file ");
return;
}
infile.Close();
MemoryStream ms = new MemoryStream();
// Use the newly created memory stream for the compressed data.
GZipStream compressedzipStream = new GZipStream(ms , CompressionMode.Compress, true);
Console.WriteLine( "Compression ");
compressedzipStream.Write(buffer, 0, buffer.Length);
// Close the stream.
compressedzipStream.Close();
Console.WriteLine( "Original size: {0}, Compressed size: {1} ", buffer.Length, ms.Length);
// Reset the memory stream position to begin decompression.
ms.Position = 0;
GZipStream zipStream = new GZipStream(ms, CompressionMode.Decompress);
Console.WriteLine( "Decompression ");
byte[] decompressedBuffer = new byte[buffer.Length + 100];
// Use the ReadAllBytesFromStream to read the stream.
int totalCount = GZipTest.ReadAllBytesFromStream(zipStream, decompressedBuffer);
Console.WriteLine( "Decompressed {0} bytes ", totalCount);
if( !GZipTest.CompareData(buffer, buffer.Length, decompressedBuffer, totalCount) )
{
Console.WriteLine( "Error. The two buffers did not compare. ");
}
zipStream.Close();
} // end try
catch (InvalidDataException)
{
Console.WriteLine( "Error: The file being read contains invalid data. ");
}
catch (FileNotFoundException)
{
Console.WriteLine( "Error:The file specified was not found. ");
}
catch (ArgumentException)
{
Console.WriteLine( "Error: path is a zero-length string, contains only white space, or contains one or more invalid characters ");
}
catch (PathTooLongException)
{
Console.WriteLine( "Error: The specified path, file name, or both exceed the system-defined maximum length. For example, on Windows-based platforms, paths must be less than 248 characters, and file names must be less than 260 characters. ");
}
catch (DirectoryNotFoundException)
{
Console.WriteLine( "Error: The specified path is invalid, such as being on an unmapped drive. ");
}
catch (IOException)
{
Console.WriteLine( "Error: An I/O error occurred while opening the file. ");
}
catch (UnauthorizedAccessException)
{
Console.WriteLine( "Error: path specified a file that is read-only, the path is a directory, or caller does not have the required permissions. ");
}
catch (IndexOutOfRangeException)
{
Console.WriteLine( "Error: You must provide parameters for MyGZIP. ");
}
}
public static void Main(string[] args)
{
string usageText = "Usage: MYGZIP <inputfilename> ";
//If no file name is specified, write usage text.
if (args.Length == 0)
{
Console.WriteLine(usageText);
}
else
{
if (File.Exists(args[0]))
GZipCompressDecompress(args[0]);
}
}
}
这里的关于byte[] decompressedBuffer = new byte[buffer.Length + 100];
这一句为什么要 用这个buffer.Length + 100？
[解决办法]
忘了，对MemoryStream不能这么处理
之前我写的是关于文件流的。
你试一下这个。
public byte[] DataDecompressToBytes(byte[] byteDestination)
{
byte[] byteResult;
MemoryStream memoryStream = new MemoryStream(byteDestination);
System.IO.Compression.DeflateStream decompressionStream = new System.IO.Compression.DeflateStream(memoryStream, CompressionMode.Decompress);
try
{
BinaryFormatter serializer = new BinaryFormatter();
object obj = serializer.Deserialize(decompressionStream);
byteResult = (byte[])obj;
decompressionStream.Close();
memoryStream.Close();
}
catch (Exception e)
{
decompressionStream.Close();
memoryStream.Close();
MessageBox.Show(e.Message);
return null;
}
return byteResult;
}
