DeflateStream.Read Methode

public:
 override int Read(Span<System::Byte> buffer);

public override int Read(Span<byte> buffer);

override this.Read : Span<byte> -> int

Public Overrides Function Read (buffer As Span(Of Byte)) As Integer

Parameters

Retouren

Het totale aantal bytes dat in de buffer is gelezen. Dit kan kleiner zijn dan het aantal bytes dat is toegewezen in de buffer als dat aantal bytes momenteel niet beschikbaar is, of nul (0) als het einde van de stream is bereikt.

Opmerkingen

Gebruik de CanRead eigenschap om te bepalen of het huidige exemplaar leesopties ondersteunt. Gebruik de ReadAsync methode om asynchroon te lezen vanuit de huidige stroom.

Met deze methode worden maximaal buffer.Length bytes uit de huidige stream gelezen en opgeslagen in buffer. De huidige positie in de stroom Deflate wordt geavanceerd door het aantal gelezen bytes; Als er echter een uitzondering optreedt, blijft de huidige positie in de stroom Deflate ongewijzigd. Deze methode wordt geblokkeerd totdat ten minste één byte aan gegevens kan worden gelezen, in het geval dat er geen gegevens beschikbaar zijn. Read retourneert alleen 0 wanneer er geen gegevens meer in de stroom staan en niet meer wordt verwacht (zoals een gesloten socket of einde van het bestand). De methode is gratis om minder bytes te retourneren dan is aangevraagd, zelfs als het einde van de stream niet is bereikt.

Gebruiken BinaryReader voor het lezen van primitieve gegevenstypen.

public:
 override int Read(cli::array <System::Byte> ^ array, int offset, int count);

public override int Read(byte[] array, int offset, int count);

override this.Read : byte[] * int * int -> int

abstract member Read : byte[] * int * int -> int
override this.Read : byte[] * int * int -> int

Public Overrides Function Read (array As Byte(), offset As Integer, count As Integer) As Integer

Parameters

Retouren

Het aantal bytes dat is gelezen in de bytematrix.

Uitzonderingen

Opmerkingen

In het volgende voorbeeld ziet u hoe u bytes kunt comprimeren en decomprimeren met behulp van de Read en Write methoden.

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

public static class MemoryWriteReadExample
{
    private const string Message = "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.";
    private static readonly byte[] s_messageBytes = Encoding.ASCII.GetBytes(Message);

    public static void Run()
    {
        Console.WriteLine($"The original string length is {s_messageBytes.Length} bytes.");
        using var stream = new MemoryStream();
        CompressBytesToStream(stream);
        Console.WriteLine($"The compressed stream length is {stream.Length} bytes.");
        int decompressedLength = DecompressStreamToBytes(stream);
        Console.WriteLine($"The decompressed string length is {decompressedLength} bytes, same as the original length.");
        /*
         Output:
            The original string length is 445 bytes.
            The compressed stream length is 265 bytes.
            The decompressed string length is 445 bytes, same as the original length.
        */
    }

    private static void CompressBytesToStream(Stream stream)
    {
        using var compressor = new DeflateStream(stream, CompressionMode.Compress, leaveOpen: true);
        compressor.Write(s_messageBytes, 0, s_messageBytes.Length);
    }

    private static int DecompressStreamToBytes(Stream stream)
    {
        stream.Position = 0;
        int bufferSize = 512;
        byte[] buffer = new byte[bufferSize];
        using var deflateStream = new DeflateStream(stream, CompressionMode.Decompress);

        int totalRead = 0;
        while (totalRead < buffer.Length)
        {
            int bytesRead = deflateStream.Read(buffer.AsSpan(totalRead));
            if (bytesRead == 0) break;
            totalRead += bytesRead;
        }

        return totalRead;
    }
}

module MemoryWriteReadExample

open System.IO
open System.IO.Compression
open System.Text

let message =
    "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."

let s_messageBytes = Encoding.ASCII.GetBytes message

let compressBytesToStream stream =
    use compressor = new DeflateStream(stream, CompressionMode.Compress, true)
    compressor.Write(s_messageBytes, 0, s_messageBytes.Length)

let decompressStreamToBytes (stream: Stream) =
    stream.Position <- 0
    let bufferSize = 512
    let decompressedBytes = Array.zeroCreate bufferSize
    use decompressor = new DeflateStream(stream, CompressionMode.Decompress)
    decompressor.Read(decompressedBytes, 0, bufferSize)

[<EntryPoint>]
let main _ =
    printfn $"The original string length is {s_messageBytes.Length} bytes."
    use stream = new MemoryStream()
    compressBytesToStream stream
    printfn $"The compressed stream length is {stream.Length} bytes."
    let decompressedLength = decompressStreamToBytes stream
    printfn $"The decompressed string length is {decompressedLength} bytes, same as the original length."
    0

// Output:
//     The original string length is 445 bytes.
//     The compressed stream length is 265 bytes.
//     The decompressed string length is 445 bytes, same as the original length.

Imports System.IO
Imports System.IO.Compression
Imports System.Text

Module MemoryWriteReadExample
    Private Const Message As String = "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."
    Private ReadOnly s_messageBytes As Byte() = Encoding.ASCII.GetBytes(Message)

    Sub Main()
        Console.WriteLine($"The original string length is {s_messageBytes.Length} bytes.")

        Using stream = New MemoryStream()
            CompressBytesToStream(stream)
            Console.WriteLine($"The compressed stream length is {stream.Length} bytes.")
            Dim decompressedLength As Integer = DecompressStreamToBytes(stream)
            Console.WriteLine($"The decompressed string length is {decompressedLength} bytes, same as the original length.")
        End Using
        ' Output:
        '   The original string length is 445 bytes.
        '   The compressed stream length is 265 bytes.
        '   The decompressed string length is 445 bytes, same as the original length.
    End Sub

    Private Sub CompressBytesToStream(ByVal stream As Stream)
        Using compressor = New DeflateStream(stream, CompressionMode.Compress, leaveOpen:=True)
            compressor.Write(s_messageBytes, 0, s_messageBytes.Length)
        End Using
    End Sub

    Private Function DecompressStreamToBytes(ByVal stream As Stream) As Integer
        stream.Position = 0
        Dim bufferSize As Integer = 512
        Dim decompressedBytes As Byte() = New Byte(bufferSize - 1) {}
        Using decompressor = New DeflateStream(stream, CompressionMode.Decompress)
            Dim length As Integer = decompressor.Read(decompressedBytes, 0, bufferSize)
            Return length
        End Using
    End Function
End Module