FromBase64Transform 类

定义

public ref class FromBase64Transform : IDisposable, System::Security::Cryptography::ICryptoTransform

public ref class FromBase64Transform : System::Security::Cryptography::ICryptoTransform

public class FromBase64Transform : IDisposable, System.Security.Cryptography.ICryptoTransform

public class FromBase64Transform : System.Security.Cryptography.ICryptoTransform

[System.Runtime.InteropServices.ComVisible(true)]
public class FromBase64Transform : System.Security.Cryptography.ICryptoTransform

type FromBase64Transform = class
    interface IDisposable
    interface ICryptoTransform

type FromBase64Transform = class
    interface ICryptoTransform
    interface IDisposable

[<System.Runtime.InteropServices.ComVisible(true)>]
type FromBase64Transform = class
    interface ICryptoTransform
    interface IDisposable

Public Class FromBase64Transform
Implements ICryptoTransform, IDisposable

Public Class FromBase64Transform
Implements ICryptoTransform

继承

Object

FromBase64Transform

属性

ComVisibleAttribute

实现

IDisposable ICryptoTransform

示例

以下示例将 base 64 编码的文件解码为输出文本文件。

using System;
using System.IO;
using System.Security.Cryptography;

class Members
{
    [STAThread]
    static void Main(string[] args)
    {
        string appPath = (System.IO.Directory.GetCurrentDirectory() );
        appPath = appPath + "..\\\\..\\\\..\\";
        // Insert your file names into this method call.
        EncodeFromFile(appPath + "program.cs", appPath + "code.enc");
        DecodeFromFile(appPath + "code.enc", appPath + "roundtrip.txt");
    }

    // Read in the specified source file and write out an encoded target file.
    private static void EncodeFromFile(string sourceFile, string targetFile) 
    {
        // Verify members.cs exists at the specified directory.
        if (!File.Exists(sourceFile))
        {
            Console.Write("Unable to locate source file located at ");
            Console.WriteLine(sourceFile + ".");
            Console.Write("Please correct the path and run the ");
            Console.WriteLine("sample again.");
            return;
        }

        // Retrieve the input and output file streams.
        using (FileStream inputFileStream =
            new FileStream(sourceFile, FileMode.Open, FileAccess.Read))
        {
            using (FileStream outputFileStream =
                new FileStream(targetFile, FileMode.Create, FileAccess.Write))
            {

                // Create a new ToBase64Transform object to convert to base 64.
                ToBase64Transform base64Transform = new ToBase64Transform();

                // Create a new byte array with the size of the output block size.
                byte[] outputBytes = new byte[base64Transform.OutputBlockSize];

                // Retrieve the file contents into a byte array.
                byte[] inputBytes = new byte[inputFileStream.Length];
                inputFileStream.Read(inputBytes, 0, inputBytes.Length);

                // Verify that multiple blocks can not be transformed.
                if (!base64Transform.CanTransformMultipleBlocks)
                {
                    // Initialize the offset size.
                    int inputOffset = 0;

                    // Iterate through inputBytes transforming by blockSize.
                    int inputBlockSize = base64Transform.InputBlockSize;

                    while (inputBytes.Length - inputOffset > inputBlockSize)
                    {
                        base64Transform.TransformBlock(
                            inputBytes,
                            inputOffset,
                            inputBytes.Length - inputOffset,
                            outputBytes,
                            0);

                        inputOffset += base64Transform.InputBlockSize;
                        outputFileStream.Write(
                            outputBytes,
                            0,
                            base64Transform.OutputBlockSize);
                    }

                    // Transform the final block of data.
                    outputBytes = base64Transform.TransformFinalBlock(
                        inputBytes,
                        inputOffset,
                        inputBytes.Length - inputOffset);

                    outputFileStream.Write(outputBytes, 0, outputBytes.Length);
                    Console.WriteLine("Created encoded file at " + targetFile);
                }

                // Determine if the current transform can be reused.
                if (!base64Transform.CanReuseTransform)
                {
                    // Free any used resources.
                    base64Transform.Clear();
                }
            }
        }
    }

        public static void DecodeFromFile(string inFileName, string outFileName)
        {
            using (FromBase64Transform myTransform = new FromBase64Transform(FromBase64TransformMode.IgnoreWhiteSpaces))
            {

                byte[] myOutputBytes = new byte[myTransform.OutputBlockSize];

                // Open the input and output files.
                using (FileStream myInputFile = new FileStream(inFileName, FileMode.Open, FileAccess.Read))
                {
                    using (FileStream myOutputFile = new FileStream(outFileName, FileMode.Create, FileAccess.Write))
                    {

                        // Retrieve the file contents into a byte array. 
                        byte[] myInputBytes = new byte[myInputFile.Length];
                        myInputFile.Read(myInputBytes, 0, myInputBytes.Length);

                        // Transform the data in chunks the size of InputBlockSize. 
                        int i = 0;
                        while (myInputBytes.Length - i > 4/*myTransform.InputBlockSize*/)
                        {
                            int bytesWritten = myTransform.TransformBlock(myInputBytes, i, 4/*myTransform.InputBlockSize*/, myOutputBytes, 0);
                            i += 4/*myTransform.InputBlockSize*/;
                            myOutputFile.Write(myOutputBytes, 0, bytesWritten);
                        }

                        // Transform the final block of data.
                        myOutputBytes = myTransform.TransformFinalBlock(myInputBytes, i, myInputBytes.Length - i);
                        myOutputFile.Write(myOutputBytes, 0, myOutputBytes.Length);

                        // Free up any used resources.
                        myTransform.Clear();
                    }
                }
            }
        }
}

Imports System.IO
Imports System.Security.Cryptography

Friend Class Members
    <STAThread()> _
    Shared Sub Main(ByVal args() As String)
        Dim appPath As String = (System.IO.Directory.GetCurrentDirectory())
        appPath = appPath & "..\\..\\..\"
        ' Insert your file names into this method call.
        EncodeFromFile(appPath & "program.vb", appPath & "code.enc")
        DecodeFromFile(appPath & "code.enc", appPath & "roundtrip.txt")

    End Sub

    ' Read in the specified source file and write out an encoded target file.
    Private Shared Sub EncodeFromFile(ByVal sourceFile As String, ByVal targetFile As String)
        ' Verify members.cs exists at the specified directory.
        If Not File.Exists(sourceFile) Then
            Console.Write("Unable to locate source file located at ")
            Console.WriteLine(sourceFile & ".")
            Console.Write("Please correct the path and run the ")
            Console.WriteLine("sample again.")
            Return
        End If

        ' Retrieve the input and output file streams.
        Using inputFileStream As New FileStream(sourceFile, FileMode.Open, FileAccess.Read)
            Using outputFileStream As New FileStream(targetFile, FileMode.Create, FileAccess.Write)

                ' Create a new ToBase64Transform object to convert to base 64.
                Dim base64Transform As New ToBase64Transform()

                ' Create a new byte array with the size of the output block size.
                Dim outputBytes(base64Transform.OutputBlockSize - 1) As Byte

                ' Retrieve the file contents into a byte array.
                Dim inputBytes(inputFileStream.Length - 1) As Byte
                inputFileStream.Read(inputBytes, 0, inputBytes.Length)

                ' Verify that multiple blocks can not be transformed.
                If Not base64Transform.CanTransformMultipleBlocks Then
                    ' Initializie the offset size.
                    Dim inputOffset As Integer = 0

                    ' Iterate through inputBytes transforming by blockSize.
                    Dim inputBlockSize As Integer = base64Transform.InputBlockSize

                    Do While inputBytes.Length - inputOffset > inputBlockSize
                        base64Transform.TransformBlock(inputBytes, inputOffset, inputBytes.Length - inputOffset, outputBytes, 0)

                        inputOffset += base64Transform.InputBlockSize
                        outputFileStream.Write(outputBytes, 0, base64Transform.OutputBlockSize)
                    Loop

                    ' Transform the final block of data.
                    outputBytes = base64Transform.TransformFinalBlock(inputBytes, inputOffset, inputBytes.Length - inputOffset)

                    outputFileStream.Write(outputBytes, 0, outputBytes.Length)
                    Console.WriteLine("Created encoded file at " & targetFile)
                End If

                ' Determine if the current transform can be reused.
                If Not base64Transform.CanReuseTransform Then
                    ' Free up any used resources.
                    base64Transform.Clear()
                End If
            End Using
        End Using

    End Sub

    Public Shared Sub DecodeFromFile(ByVal inFileName As String, ByVal outFileName As String)
        Using myTransform As New FromBase64Transform(FromBase64TransformMode.IgnoreWhiteSpaces)

            Dim myOutputBytes(myTransform.OutputBlockSize - 1) As Byte

            'Open the input and output files.
            Using myInputFile As New FileStream(inFileName, FileMode.Open, FileAccess.Read)
                Using myOutputFile As New FileStream(outFileName, FileMode.Create, FileAccess.Write)

                    'Retrieve the file contents into a byte array. 
                    Dim myInputBytes(myInputFile.Length - 1) As Byte
                    myInputFile.Read(myInputBytes, 0, myInputBytes.Length)

                    'Transform the data in chunks the size of InputBlockSize. 
                    Dim i As Integer = 0
                    Do While myInputBytes.Length - i > 4 'myTransform.InputBlockSize
                        Dim bytesWritten As Int32 = myTransform.TransformBlock(myInputBytes, i, 4, myOutputBytes, 0) 'myTransform.InputBlockSize
                        i += 4 'myTransform.InputBlockSize
                        myOutputFile.Write(myOutputBytes, 0, bytesWritten)
                    Loop

                    'Transform the final block of data.
                    myOutputBytes = myTransform.TransformFinalBlock(myInputBytes, i, myInputBytes.Length - i)
                    myOutputFile.Write(myOutputBytes, 0, myOutputBytes.Length)

                    'Free up any used resources.
                    myTransform.Clear()
                End Using
            End Using
        End Using

    End Sub
End Class

注解

Base 64 内容传输编码以人类不可读的形式表示任意位序列。

另请参阅

• 加密服务