XmlTextWriter.WriteBase64(Byte[], Int32, Int32) Metodo
Definizione
Importante
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Codifica i byte binari specificati come valori Base64 e scrive il testo risultante.
public:
override void WriteBase64(cli::array <System::Byte> ^ buffer, int index, int count);
public override void WriteBase64 (byte[] buffer, int index, int count);
override this.WriteBase64 : byte[] * int * int -> unit
Public Overrides Sub WriteBase64 (buffer As Byte(), index As Integer, count As Integer)
Parametri
- buffer
- Byte[]
Matrice di byte da codificare.
- index
- Int32
Posizione all'interno del buffer che indica l'inizio dei byte da scrivere.
- count
- Int32
Numero di byte da scrivere.
Eccezioni
buffer
è null
.
La lunghezza del buffer meno index
è minore di count
.
index
o count
è minore di zero.
L'elemento WriteState è Closed
.
Esempio
Nell'esempio seguente viene codificato un file di input usando WriteBase64
e viene generato un file XML temporaneo. Il file XML temporaneo viene decodificato usando il metodo e confrontato con il ReadBase64 file originale.
#using <System.Xml.dll>
using namespace System;
using namespace System::IO;
using namespace System::Xml;
using namespace System::Text;
ref class TestBase64
{
private:
static int bufferSize = 4096;
public:
// Use the WriteBase64 method to create an XML document. The object
// passed by the user is encoded and included in the document.
void EncodeXmlFile( String^ xmlFileName, FileStream^ fileOld )
{
array<Byte>^buffer = gcnew array<Byte>(bufferSize);
int readByte = 0;
XmlTextWriter^ xw = gcnew XmlTextWriter( xmlFileName,Encoding::UTF8 );
xw->WriteStartDocument();
xw->WriteStartElement( "root" );
// Create a Char writer.
BinaryReader^ br = gcnew BinaryReader( fileOld );
// Set the file pointer to the end.
try
{
do
{
readByte = br->Read( buffer, 0, bufferSize );
xw->WriteBase64( buffer, 0, readByte );
}
while ( bufferSize <= readByte );
}
catch ( Exception^ ex )
{
EndOfStreamException^ ex1 = gcnew EndOfStreamException;
if ( ex1->Equals( ex ) )
Console::WriteLine( "We are at end of file" );
else
Console::WriteLine( ex );
}
xw->WriteEndElement();
xw->WriteEndDocument();
xw->Flush();
xw->Close();
}
// Use the ReadBase64 method to decode the new XML document
// and generate the original object.
void DecodeOrignalObject( String^ xmlFileName, FileStream^ fileNew )
{
array<Byte>^buffer = gcnew array<Byte>(bufferSize);
int readByte = 0;
// Create a file to write the bmp back.
BinaryWriter^ bw = gcnew BinaryWriter( fileNew );
XmlTextReader^ tr = gcnew XmlTextReader( xmlFileName );
tr->MoveToContent();
Console::WriteLine( tr->Name );
do
{
readByte = tr->ReadBase64( buffer, 0, bufferSize );
bw->Write( buffer, 0, readByte );
}
while ( readByte >= bufferSize );
bw->Flush();
}
// Compare the two files.
bool CompareResult( FileStream^ fileOld, FileStream^ fileNew )
{
int readByteOld = 0;
int readByteNew = 0;
int count;
int readByte = 0;
array<Byte>^bufferOld = gcnew array<Byte>(bufferSize);
array<Byte>^bufferNew = gcnew array<Byte>(bufferSize);
BinaryReader^ binaryReaderOld = gcnew BinaryReader( fileOld );
BinaryReader^ binaryReaderNew = gcnew BinaryReader( fileNew );
binaryReaderOld->BaseStream->Seek( 0, SeekOrigin::Begin );
binaryReaderNew->BaseStream->Seek( 0, SeekOrigin::Begin );
do
{
readByteOld = binaryReaderOld->Read( bufferOld, 0, bufferSize );
readByteNew = binaryReaderNew->Read( bufferNew, 0, bufferSize );
if ( readByteOld != readByteNew )
return false;
for ( count = 0; count < bufferSize; ++count )
if ( bufferOld[ count ] != bufferNew[ count ] )
return false;
}
while ( count < readByte );
return true;
}
// Display the usage statement.
void Usage()
{
Console::WriteLine( "TestBase64 sourceFile, targetFile \n" );
Console::WriteLine( "For example: TestBase64 winlogon.bmp, target.bmp\n" );
}
};
int main()
{
array<String^>^args = Environment::GetCommandLineArgs();
TestBase64^ testBase64 = gcnew TestBase64;
// Check that the usage is correct.
if ( args->Length < 3 )
{
testBase64->Usage();
return 1;
}
FileStream^ fileOld = gcnew FileStream( args[ 1 ],FileMode::OpenOrCreate,FileAccess::Read,FileShare::Read );
testBase64->EncodeXmlFile( "temp.xml", fileOld );
FileStream^ fileNew = gcnew FileStream( args[ 2 ],FileMode::Create,FileAccess::ReadWrite,FileShare::ReadWrite );
testBase64->DecodeOrignalObject( "temp.xml", fileNew );
// Compare the two files.
if ( testBase64->CompareResult( fileOld, fileNew ) )
Console::WriteLine( "The recreated binary file {0} is the same as {1}", args[ 2 ], args[ 1 ] );
else
Console::WriteLine( "The recreated binary file {0} is not the same as {1}", args[ 2 ], args[ 1 ] );
fileOld->Flush();
fileNew->Flush();
fileOld->Close();
fileNew->Close();
return 0;
}
using System;
using System.IO;
using System.Xml;
using System.Text;
public static class TestBase64
{
private const int bufferSize = 4096;
public static void Main(string[] args)
{
// Check that the usage string is correct.
if (args.Length < 2)
{
TestBase64.Usage();
return;
}
var fileOld = new FileStream(args[0], FileMode.OpenOrCreate, FileAccess.Read, FileShare.Read);
TestBase64.EncodeXmlFile("temp.xml", fileOld);
var fileNew = new FileStream(args[1], FileMode.Create, FileAccess.ReadWrite, FileShare.ReadWrite);
TestBase64.DecodeOrignalObject("temp.xml", fileNew);
// Compare the two files.
if (TestBase64.CompareResult(fileOld, fileNew))
{
Console.WriteLine($"The recreated binary file {args[1]} is the same as {args[0]}");
}
else
{
Console.WriteLine($"The recreated binary file {args[1]} is not the same as {args[0]}");
}
fileOld.Flush();
fileNew.Flush();
fileOld.Close();
fileNew.Close();
}
// Use the WriteBase64 method to create an XML document. The object
// passed by the user is encoded and included in the document.
public static void EncodeXmlFile(string xmlFileName, FileStream fileOld)
{
var buffer = new byte[bufferSize];
int readByte = 0;
var xw = new XmlTextWriter(xmlFileName, Encoding.UTF8);
xw.WriteStartDocument();
xw.WriteStartElement("root");
// Create a Char writer.
var br = new BinaryReader(fileOld);
// Set the file pointer to the end.
try
{
do
{
readByte = br.Read(buffer, 0, bufferSize);
xw.WriteBase64(buffer, 0, readByte);
} while (bufferSize <= readByte);
}
catch (Exception ex)
{
var ex1 = new EndOfStreamException();
if (ex1.Equals(ex))
{
Console.WriteLine("We are at end of file");
}
else
{
Console.WriteLine(ex);
}
}
xw.WriteEndElement();
xw.WriteEndDocument();
xw.Flush();
xw.Close();
}
// Use the ReadBase64 method to decode the new XML document
// and generate the original object.
public static void DecodeOrignalObject(string xmlFileName, FileStream fileNew)
{
var buffer = new byte[bufferSize];
int readByte = 0;
// Create a file to write the bmp back.
var bw = new BinaryWriter(fileNew);
var tr = new XmlTextReader(xmlFileName);
tr.MoveToContent();
Console.WriteLine(tr.Name);
do
{
readByte=tr.ReadBase64(buffer, 0, bufferSize);
bw.Write(buffer, 0, readByte);
} while(readByte >= bufferSize);
bw.Flush();
}
// Compare the two files.
public static bool CompareResult(FileStream fileOld, FileStream fileNew) {
int readByteOld = 0;
int readByteNew = 0;
int count, readByte =0 ;
var bufferOld = new byte[bufferSize];
var bufferNew = new byte[bufferSize];
var binaryReaderOld = new BinaryReader(fileOld);
var binaryReaderNew = new BinaryReader(fileNew);
binaryReaderOld.BaseStream.Seek(0, SeekOrigin.Begin);
binaryReaderNew.BaseStream.Seek(0, SeekOrigin.Begin);
do
{
readByteOld = binaryReaderOld.Read(bufferOld, 0, bufferSize);
readByteNew = binaryReaderNew.Read(bufferNew, 0, bufferSize);
if (readByteOld != readByteNew)
{
return false;
}
for (count = 0; count < bufferSize; count++)
{
if (bufferOld[count] != bufferNew[count])
{
return false;
}
}
} while (count < readByte);
return true;
}
// Display the usage statement.
public static void Usage()
{
Console.WriteLine("TestBase64 sourceFile, targetFile \n");
Console.WriteLine("For example: TestBase64 winlogon.bmp, target.bmp\n");
}
}
Imports System.IO
Imports System.Xml
Imports System.Text
Public Module TestBase64
Private Const bufferSize As Integer = 4096
Public Sub Main()
Dim args As String() = System.Environment.GetCommandLineArgs()
' Check that the usage string is correct.
If args.Length < 3
TestBase64.Usage()
Return
End If
Dim fileOld As New FileStream(args(1), FileMode.OpenOrCreate, FileAccess.Read, FileShare.Read)
TestBase64.EncodeXmlFile("temp.xml", fileOld)
Dim fileNew As New FileStream(args(2), FileMode.Create, FileAccess.ReadWrite, FileShare.ReadWrite)
TestBase64.DecodeOrignalObject("temp.xml", fileNew)
' Compare the two files.
If TestBase64.CompareResult(fileOld, fileNew)
Console.WriteLine($"The recreated binary file {args(2)} is the same as {args(1)}")
Else
Console.WriteLine($"The recreated binary file {args(2)} is not the same as {args(1)}")
End If
fileOld.Flush()
fileNew.Flush()
fileOld.Close()
fileNew.Close()
End Sub
' Use the WriteBase64 method to create an XML document. The object
' passed by the user is encoded and included in the document.
Public Sub EncodeXmlFile(xmlFileName As String, fileOld As FileStream)
Dim buffer(bufferSize - 1) As Byte
Dim readByte As Integer = 0
Dim xw As New XmlTextWriter(xmlFileName, Encoding.UTF8)
xw.WriteStartDocument()
xw.WriteStartElement("root")
' Create a Char writer.
Dim br As New BinaryReader(fileOld)
' Set the file pointer to the end.
Try
Do
readByte = br.Read(buffer, 0, bufferSize)
xw.WriteBase64(buffer, 0, readByte)
Loop While (bufferSize <= readByte)
Catch ex As Exception
Dim ex1 As New EndOfStreamException()
If (ex1.Equals(ex))
Console.WriteLine("We are at end of file")
Else
Console.WriteLine(ex)
End If
End Try
xw.WriteEndElement()
xw.WriteEndDocument()
xw.Flush()
xw.Close()
End Sub
' Use the ReadBase64 method to decode the new XML document
' and generate the original object.
Public Sub DecodeOrignalObject(xmlFileName As String, fileNew As FileStream)
Dim buffer(bufferSize - 1) As Byte
Dim readByte As Integer = 0
' Create a file to write the bmp back.
Dim bw As New BinaryWriter(fileNew)
Dim tr As New XmlTextReader(xmlFileName)
tr.MoveToContent()
Console.WriteLine(tr.Name)
Do
readByte = tr.ReadBase64(buffer, 0, bufferSize)
bw.Write(buffer, 0, readByte)
Loop While (readByte >= bufferSize)
bw.Flush()
End Sub
' Compare the two files.
Public Function CompareResult(fileOld As FileStream, fileNew As FileStream) As Boolean
Dim readByteOld As Integer = 0
Dim readByteNew As Integer = 0
Dim count As Integer
Dim readByte as integer = 0
Dim bufferOld(bufferSize - 1) As Byte
Dim bufferNew(bufferSize - 1) As Byte
Dim binaryReaderOld As New BinaryReader(fileOld)
Dim binaryReaderNew As New BinaryReader(fileNew)
binaryReaderOld.BaseStream.Seek(0, SeekOrigin.Begin)
binaryReaderNew.BaseStream.Seek(0, SeekOrigin.Begin)
Do
readByteOld = binaryReaderOld.Read(bufferOld, 0, bufferSize)
readByteNew = binaryReaderNew.Read(bufferNew, 0, bufferSize)
If readByteOld <> readByteNew
Return False
End If
For count = 0 To bufferSize - 1
If bufferOld(count) <> bufferNew(count)
Return False
End If
Next
Loop While (count < readByte)
Return True
End Function
' Display the usage statement.
Public Sub Usage()
Console.WriteLine("TestBase64 sourceFile, targetFile")
Console.WriteLine("For example: TestBase64 winlogon.bmp, target.bmp")
End Sub
End Module
Commenti
Nota
A partire da .NET Framework 2.0, è consigliabile creare XmlWriter istanze usando il metodo e la XmlWriter.CreateXmlWriterSettings classe per sfruttare nuove funzionalità.