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DeflateStream Constructor (Stream, CompressionMode)

Note: This constructor is new in the .NET Framework version 2.0.

Initializes a new instance of the DeflateStream class using the specified stream and CompressionMode value.

Namespace: System.IO.Compression
Assembly: System (in system.dll)

public DeflateStream (
	Stream stream,
	CompressionMode mode
)
public DeflateStream (
	Stream stream, 
	CompressionMode mode
)
public function DeflateStream (
	stream : Stream, 
	mode : CompressionMode
)

Parameters

stream

The stream to compress or decompress.

mode

One of the CompressionMode values that indicates the action to take.

Exception typeCondition

ArgumentNullException

stream is a null reference (Nothing in Visual Basic).

InvalidOperationException

stream access right is ReadOnly and mode value is Compress.

ArgumentException

mode is not a valid CompressionMode value.

-or-

CompressionMode is Compress and CanWrite is false.

-or-

CompressionMode is Decompress and CanWrite is false.

By default, DeflateStream owns the underlying stream, so closing the stream also closes the underlying stream. Note that the state of the underlying stream can affect the usability of the stream. Also, no explicit checks are performed, so no additional exceptions are thrown when the new instance is created.

If an instance of the DeflateStream class is created with the mode parameter equal to Compress, header information is inserted immediately. If no further action occurs, the stream appears as a valid, empty, compressed file.

Using the DeflateStream class to compress a file larger than 4 GB raises an exception.

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

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]);
		}
	}
}
	

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

public class DeflateTest
{
    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 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);
            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.
            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}", 
                System.Convert.ToString(buffer.length), 
                System.Convert.ToString(ms.get_Length()));

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

            // Use the ReadAllBytesFromStream to read the stream.
            int totalCount = DeflateTest.ReadAllBytesFromStream(zipStream, 
                decompressedBuffer);
            Console.WriteLine("Decompressed {0} bytes", 
                System.Convert.ToString(totalCount));

            if (!(DeflateTest.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.");
        }
    } //DeflateCompressDecompress

    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]);
            }
        }
    } //main
} //DeflateTest

Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.

.NET Framework

Supported in: 2.0
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