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GZipStream Classe

Fornece métodos e propriedades usadas para compactar e descompactar fluxos.

Namespace:  System.IO.Compression
Assembly:  System (em System. dll)

public class GZipStream : Stream

Esta classe representa o Formatarar de dados GZIP, que usa um algoritmo padrão da indústria para a compactação de arquivos sem perdas e descompactação.O Formatarar inclui uma redundância cíclica Marcar valor para detectar dano dados.The gzip data format uses the same algorithm as the DeflateStream class, but can be extended to use other compression formats.O Formatarar pode ser prontamente implementado de maneira não coberta pelo patentes.The format for gzip is available from the RFC 1952, "GZIP file format specification 4.3." Essa classe não pode ser usada para compactar arquivos mais que 4 GB.

Compressed GZipStream objects written to a file with an extension of .gz can be decompressed using many common compression tools; however, this class does not inherently provide functionality for adding files to or extracting files from .zip archives.For an example of compressing and decompressing files in the gzip data format, see Compression Aplicativo Exemplo.

The compression functionality in DeflateStream and GZipStream is exposed as a stream.Dados ler em um byte - por - base byte, portanto, não é possível executar Múltiplo passa para determinar o melhor método para compactar arquivos inteiros ou blocos grandes de dados.The DeflateStream and GZipStream classes are best used on uncompressed sources of data.Se os dados de origem já estiver compactados, usar essas classes realmente pode aumentar o tamanho do fluxo.

OBSERVAÇÕES PARA Inheritors:

When you inherit from GZipStream, you must override the following members: CanSeek, CanWrite, and CanRead.

The following code example shows how to use the GZipStream class to compress and decompress a file.

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]);
		}
	}
}
	


import System.*;
import System.IO.*;
import System.IO.Compression.*;

public class GZipTest
{
    public static int ReadAllBytesFromStream(Stream stream, ubyte 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;
    } //ReadAllBytesFromStream

    public static boolean CompareData(ubyte buf1[], int len1, 
        ubyte 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}", System.Convert.ToString(len1), 
                System.Convert.ToString(len2));
            return false;
        }
        for (int i = 0; i < len1; i++) {
            if (!(buf1.get_Item(i).Equals(buf2.get_Item(i)))) {
                Console.WriteLine("byte {0} is different {1}|{2}", 
                    System.Convert.ToString(i), 
                    System.Convert.ToString(buf1.get_Item(i)), 
                    System.Convert.ToString(buf2.get_Item(i)));
                return false;
            }
        }
        Console.WriteLine("All bytes compare.");
        return true;
    } //CompareData

    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);
            ubyte buffer[] = new ubyte[(ubyte)inFile.get_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}", 
                System.Convert.ToString(buffer.length), 
                System.Convert.ToString(ms.get_Length()));

            // Reset the memory stream position to begin decompression.
            ms.set_Position(0);
            GZipStream zipStream = 
                new GZipStream(ms, CompressionMode.Decompress);
            Console.WriteLine("Decompression");
            ubyte decompressedBuffer[] = new ubyte[buffer.length + 100];

            // Use the ReadAllBytesFromStream to read the stream.
            int totalCount = GZipTest.ReadAllBytesFromStream(zipStream, 
                decompressedBuffer);
            Console.WriteLine("Decompressed {0} bytes", 
                System.Convert.ToString(totalCount));
            if (!(GZipTest.CompareData(buffer, buffer.length, 
                decompressedBuffer, totalCount))) {
                Console.WriteLine("Error. The two buffers did not compare.");
            }
            zipStream.Close();
        } 
        catch (InvalidDataException exp) {
            Console.WriteLine("Error: The file being read contains"
                + " invalid data.");
        }
        catch (FileNotFoundException exp) {
            Console.WriteLine("Error:The file specified was not found.");
        }
        catch (ArgumentException exp) {
            Console.WriteLine("Error: path is a zero-length string, contains "
                + "only white space, or contains one or more invalid characters");
        }
        catch (PathTooLongException exp) {
            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 exp) {
            Console.WriteLine("Error: The specified path is invalid, such"
                + " as being on an unmapped drive.");
        }
        catch (IOException exp) {
            Console.WriteLine("Error: An I/O error occurred while "
                + "opening the file.");
        }
        catch (UnauthorizedAccessException exp) {
            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 exp) {
            Console.WriteLine("Error: You must provide parameters for MyGZIP.");
        }
    } //GZipCompressDecompress

    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]);
            }
        }
    } //main
} //GZipTest


System.Object
  System.MarshalByRefObject
    System.IO.Stream
      System.IO.Compression.GZipStream

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