استفاده از DeflateStream ؟

[Ahmadali_B]

چگونه میتوان با استفاده از DeflateStream یک فایل را Compress و ِ Decompress کرد؟ (لطفا نمونه کد #C)

[khaste_007]

با سلام
کد زیر را بررسی کنید :

using System;
using System.IO;
using System.IO.Compression;

public class DeflateTest
{
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 DeflateCompressDecompress(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.
DeflateStream compressedzipStream = new DeflateStream(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;
DeflateStream zipStream = new DeflateStream(ms, CompressionMode.Decompress);
Console.WriteLine("Decompression");
byte[] decompressedBuffer = new byte[buffer.Length + 100];
// Use the ReadAllBytesFromStream to read the stream.
int totalCount = DeflateTest.ReadAllBytesFromStream(zipStream, decompressedBuffer);
Console.WriteLine("Decompressed {0} bytes", totalCount);

if( !DeflateTest.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: DeflateTest <inputfilename>";
//If no file name is specified, write usage text.
if (args.Length == 0)
{
Console.WriteLine(usageText);
}
else
{
if (File.Exists(args[0]))
DeflateCompressDecompress(args[0]);
}
}
}
برای مطالعه بیشتر می توانید لینک زیر را مشاهده کنید:
http://msdn.microsoft.com/en-us/library/system.io.compression.deflatestream.aspx