Сжатие файлов

Используйте класс GZipStream для сжатия и распаковки данных. Следующий пример кода создает файл (test.txt) в текущем каталоге, заполняет его текстом и выводит содержимое файла на консоль. Затем в коде используется класс GZipStream для создания сжатой версии файла (test.txt.gz) и сравнивается размер двух файлов. В заключение в коде выполняется считывание данных из сжатого файла, его распаковка и запись нового файла (test.txt.gz.txt) в текущий каталог. Затем выводится содержимое распакованного файла.

Также можно использовать класс DeflateStream для сжатия и распаковки данных.

Пример

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Console.WriteLine("Contents of {0}", path);

Console.WriteLine(File.ReadAllText(path));

CompressFile(path);

Console.WriteLine();

UncompressFile(path + ".gz");

Console.WriteLine();

Console.WriteLine("Contents of {0}", path + ".gz.txt");

Console.WriteLine(File.ReadAllText(path + ".gz.txt"));

}

public static void CompressFile(string path)

{

FileStream sourceFile = File.OpenRead(path);

FileStream destinationFile = File.Create(path + ".gz");

byte[] buffer = new byte[sourceFile.Length];

sourceFile.Read(buffer, 0, buffer.Length);

using (GZipStream output = new GZipStream(destinationFile,

CompressionMode.Compress))

{

Console.WriteLine("Compressing {0} to {1}.", sourceFile.Name,

destinationFile.Name, false);

output.Write(buffer, 0, buffer.Length);

}

// Close the files.

sourceFile.Close();

destinationFile.Close();

}

public static void UncompressFile(string path)

{

FileStream sourceFile = File.OpenRead(path);

FileStream destinationFile = File.Create(path + ".txt");

// Because the uncompressed size of the file is unknown,

// we are using an arbitrary buffer size.

byte[] buffer = new byte[4096];

int n;

using (GZipStream input = new GZipStream(sourceFile,

CompressionMode.Decompress, false))

{

Console.WriteLine("Decompressing {0} to {1}.", sourceFile.Name,

destinationFile.Name);

n = input.Read(buffer, 0, buffer.Length);

destinationFile.Write(buffer, 0, n);

}

// Close the files.

sourceFile.Close();

destinationFile.Close();

}

}

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Composing Streams

A backing store is a storage medium, such as a disk or memory. Each different backing store implements its own stream as an implementation of the Stream class. Each stream type reads and writes bytes from and to its given backing store. Streams that connect to backing stores are called base streams. Base streams have constructors that have the parameters necessary to connect the stream to the backing store. For example, FileStream has constructors that specify a path parameter, which specifies how the file will be shared by processes, and so on.

The design of the System.IO classes provides simplified stream composing. Base streams can be attached to one or more pass-through streams that provide the functionality you want. A reader or writer can be attached to the end of the chain so that the preferred types can be read or written easily.

The following code example creates a FileStream around the existing MyFile.txt in order to buffer MyFile.txt. (Note that FileStreams are buffered by default.) Next, a StreamReader is created to read characters from the FileStream, which is passed to the StreamReader as its constructor argument. ReadLine reads until Peek finds no more characters.