IFormatProvider-Schnittstelle
.NET Framework 2.0
Stellt einen Mechanismus für das Abrufen eines Objekts zur Steuerung der Formatierung bereit.
Namespace: System
Assembly: mscorlib (in mscorlib.dll)
Assembly: mscorlib (in mscorlib.dll)
Einige Methoden der Common Language Runtime konvertieren einen Wert in eine Zeichenfolgenentsprechung und aus dieser und verwenden einen Zeichenfolgenparameter aus einem oder mehreren Buchstaben, den so genannten Formatbezeichnern, die angeben, wie der Wert konvertiert werden soll. Wenn die Bedeutung des Formatbezeichners von der Kultur abhängig ist, werden die in der Zeichenfolgenentsprechung tatsächlich verwendeten Zeichen von einem Formatierungsobjekt geliefert.
Ein Klassen- oder Werttyp implementiert die GetFormat-Methode dieser Schnittstelle zum Abrufen eines Objekts, das Formatinformationen oder die -verarbeitung für den entsprechenden Typ bereitstellt.
IFormatProvider wird z. B. von NumberFormatInfo und DateTimeFormatInfo implementiert. NumberFormatInfo stellt kulturabhängige Informationen zur Formatierung von Zahlen in den Basisdatentypen bereit, und DateTimeFormatInfo gibt kulturabhängige Informationen zur Formatierung von Datums- und Zeitwerten an.
Im folgenden Codebeispiel wird die Verwendung einer Klasse veranschaulicht, die die IFormatProvider-Schnittstelle und die GetFormat-Methode implementiert. Die AnyRadix-Klasse unterstützt den Formatierungscode "Ra" und konvertiert einen Int64-Wert in eine Zeichenfolge mit einer angegebenen beliebigen Basis zwischen 2 und 36. GetFormat gibt einen Verweis auf sich selbst zurück, wenn der Type-Parameter auf eine Klasse verweist, die ICustomFormatter implementiert. Andernfalls gibt GetFormatNULL (Nothing in Visual Basic) zurück.
// Sample for the IFormatProvider interface and // the IFormatProvider.GetFormat( Type ) method. using System; // This class implements the "Ra" formatting code. An instance of this // class should be passed to methods requiring an IFormatProvider. public class AnyRadix : ICustomFormatter, IFormatProvider { // The value to be formatted is returned as a signed string // of digits from the rDigits array. const string radixCode = "Ra"; private static char[] rDigits = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z' }; // This method returns an object that implements ICustomFormatter // to do the formatting. public object GetFormat( Type argType ) { // Here, the same object (this) is returned, but it would // be possible to return an object of a different type. if ( argType == typeof( ICustomFormatter ) ) return this; else return null; } // This method does the formatting only if it recognizes the // format codes. public string Format( string formatString, object argToBeFormatted, IFormatProvider provider ) { // If no format string is provided or the format string cannot // be handled, use IFormattable or standard string processing. if( formatString == null || ! formatString.Trim( ).StartsWith( radixCode ) ) { if( argToBeFormatted is IFormattable ) return ( (IFormattable)argToBeFormatted ). ToString( formatString, provider ); else return argToBeFormatted.ToString( ); } // The formatting is handled here. int digitIndex = 0; long radix; long longToBeFormatted; long longPositive; char[ ] outDigits = new char[ 63 ]; // Extract the radix from the format string. formatString = formatString.Replace( radixCode, "" ); try { radix = Convert.ToInt64( formatString ); } catch( Exception ex ) { throw new ArgumentException( String.Format( "The radix \"{0}\" is invalid.", formatString ), ex ); } // Verify that the radix is in the proper range. if( radix <2 || radix > 36 ) throw new ArgumentException( String.Format( "The radix \"{0}\" is not in the range 2..36.", formatString ) ); // Verify that the argument can be converted to a long integer. try { longToBeFormatted = (long)argToBeFormatted; } catch( Exception ex ) { throw new ArgumentException( String.Format( "The argument \"{0}\" cannot be " + "converted to an integer value.", argToBeFormatted ), ex ); } // Extract the magnitude for conversion. longPositive = Math.Abs( longToBeFormatted ); // Convert the magnitude to a digit string. for( digitIndex = 0; digitIndex <= 64; digitIndex++ ) { if( longPositive == 0 ) break; outDigits[ outDigits.Length - digitIndex - 1 ] = rDigits[ longPositive % radix ]; longPositive /= radix; } // Add a minus sign if the argument is negative. if( longToBeFormatted < 0 ) outDigits[ outDigits.Length - digitIndex++ - 1 ] = '-'; return new string( outDigits, outDigits.Length - digitIndex, digitIndex ); } } class IFormatProviderDemo { static void ConvertToAnyRadix( object argToConvert, string formatStr ) { AnyRadix provider = new AnyRadix( ); string messageStr = String.Format( "{{0:{0}}}", formatStr ); // Write the first part of the output line. Console.Write( "{0,18} {1,-6}", argToConvert, formatStr ); // Convert the specified argument using the specified format. try { Console.WriteLine( String.Format( provider, messageStr, argToConvert ) ); } catch( Exception ex ) { // Display the exception without the stack trace. int lineEnd = ex.ToString( ).IndexOf( '\n' ); Console.WriteLine( "{0}\n", ex.ToString( ).Substring( 0, lineEnd ) ); } } static void Main( ) { long twoToThe32 = 4294967296; long fifteenNines = 999999999999999; Console.WriteLine( "This example of the IFormatProvider interface \n" + "and the IFormatProvider.GetFormat( Type ) method " + "\ngenerates the following output.\n" ); Console.WriteLine( "{0,18} Format Result", "Number" ); Console.WriteLine( "{0,18} ------ ------", "------" ); // These are valid conversions. ConvertToAnyRadix( twoToThe32, "Ra2" ); ConvertToAnyRadix( twoToThe32, "Ra5" ); ConvertToAnyRadix( twoToThe32, "Ra16" ); ConvertToAnyRadix( twoToThe32, "Ra23" ); ConvertToAnyRadix( twoToThe32, "Ra36" ); ConvertToAnyRadix( fifteenNines, "Ra2" ); ConvertToAnyRadix( fifteenNines, "Ra3" ); ConvertToAnyRadix( fifteenNines, "Ra8" ); ConvertToAnyRadix( fifteenNines, "Ra11" ); ConvertToAnyRadix( fifteenNines, "Ra16" ); ConvertToAnyRadix( fifteenNines, "Ra23" ); ConvertToAnyRadix( fifteenNines, "Ra36" ); ConvertToAnyRadix( fifteenNines, "E16" ); ConvertToAnyRadix( fifteenNines, "" ); // These are error conditions. ConvertToAnyRadix( fifteenNines, "Ra37" ); ConvertToAnyRadix( "ABCDEFGHIJKLM", "Ra16" ); } } /* This example of the IFormatProvider interface and the IFormatProvider.GetFormat( Type ) method generates the following output. Number Format Result ------ ------ ------ 4294967296 Ra2 100000000000000000000000000000000 4294967296 Ra5 32244002423141 4294967296 Ra16 100000000 4294967296 Ra23 1606K7IC 4294967296 Ra36 1Z141Z4 999999999999999 Ra2 11100011010111111010100100110001100111111111111111 999999999999999 Ra3 11212010201001210101011021212000 999999999999999 Ra8 34327724461477777 999999999999999 Ra11 26A6A3689065639 999999999999999 Ra16 38D7EA4C67FFF 999999999999999 Ra23 1134DIFHLMM4 999999999999999 Ra36 9UGXNORJLR 999999999999999 E16 9.9999999999999900E+014 999999999999999 999999999999999 999999999999999 Ra37 System.ArgumentException: The radix "37" is not in th e range 2..36. ABCDEFGHIJKLM Ra16 System.ArgumentException: The argument "ABCDEFGHIJKLM " cannot be converted to an integer value. ---> System.InvalidCastException: Sp ecified cast is not valid. */
// Sample for the IFormatProvider interface and
// the IFormatProvider.GetFormat( Type ) method.
import System.*;
// This class implements the "Ra" formatting code. An instance of this
// class should be passed to methods requiring an IFormatProvider.
public class AnyRadix implements ICustomFormatter,IFormatProvider
{
// The value to be formatted is returned as a signed string
// of digits from the rDigits array.
private String radixCode = "Ra";
private static char rDigits[] = {
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',
'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',
'U', 'V', 'W', 'X', 'Y', 'Z' };
// This method returns an object that implements ICustomFormatter
// to do the formatting.
public Object GetFormat(Type argType)
{
// Here, the same object (this) is returned, but it would
// be possible to return an object of a different type.
if ( argType.Equals(ICustomFormatter.class.ToType()) ) {
return this ;
}
else {
return null ;
}
} //GetFormat
// This method does the formatting only if it recognizes the
// format codes.
public String Format(String formatString, Object argToBeFormatted,
IFormatProvider provider)
{
// If no format string is provided or the format string cannot
// be handled, use IFormattable or standard string processing.
if(formatString == null||!(formatString.Trim().StartsWith(radixCode))) {
if ( argToBeFormatted instanceof IFormattable ) {
return((IFormattable)(argToBeFormatted)).
ToString(formatString,provider);
}
else {
return argToBeFormatted.ToString();
}
}
// The formatting is handled here.
int digitIndex = 0;
long radix;
long longToBeFormatted;
long longPositive;
char outDigits[] = new char[63];
// Extract the radix from the format string.
formatString = formatString.Replace(radixCode, "");
try {
radix = Convert.ToInt64(formatString);
}
catch(System.Exception ex) {
throw new ArgumentException(String.Format(
"The radix \"{0}\" is invalid.", formatString), ex);
}
// Verify that the radix is in the proper range.
if ( radix < 2 || radix > 36 ) {
throw new ArgumentException(String.Format(
"The radix \"{0}\" is not in the range 2..36.", formatString));
}
// Verify that the argument can be converted to a long integer.
try {
longToBeFormatted =(long)System.Convert.ToUInt64(argToBeFormatted);
}
catch(System.Exception ex) {
throw new ArgumentException(String.Format(
"The argument \"{0}\" cannot be "
+ "converted to an integer value.", argToBeFormatted), ex);
}
// Extract the magnitude for conversion.
longPositive = System.Math.Abs(longToBeFormatted);
// Convert the magnitude to a digit string.
for(digitIndex = 0;digitIndex <= 64;digitIndex++) {
if ( longPositive == 0 ) {
break ;
}
outDigits[outDigits.length - digitIndex - 1] =
rDigits[(int)(longPositive % radix)];
longPositive /= radix;
}
// Add a minus sign if the argument is negative.
if ( longToBeFormatted < 0 ) {
outDigits [outDigits.length - digitIndex ++ - 1] = '-';
}
return new String(outDigits, outDigits.length - digitIndex, digitIndex);
} //Format
} //AnyRadix
class IFormatProviderDemo
{
static void ConvertToAnyRadix(Object argToConvert, String formatStr)
{
AnyRadix provider = new AnyRadix();
String messageStr = String.Format("{{0:{0}}}", formatStr);
// Write the first part of the output line.
Console.Write("{0,18} {1,-6}", argToConvert, formatStr);
// Convert the specified argument using the specified format.
try {
Console.WriteLine(String.Format((IFormatProvider)provider,
messageStr,new Object[]{ argToConvert}));
}
catch(System.Exception ex) {
// Display the exception without the stack trace.
int lineEnd = ex.ToString().IndexOf('\n');
Console.WriteLine("{0}\n", ex.ToString().Substring(0, lineEnd));
}
} //ConvertToAnyRadix
public static void main(String[] args)
{
long twoToThe32 = 4294967296L;
long fifteenNines = 999999999999999L;
Console.WriteLine(("This example of the IFormatProvider interface \n"
+ "and the IFormatProvider.GetFormat( Type ) method "
+ "\ngenerates the following output.\n"));
Console.WriteLine("{0,18} Format Result", "Number");
Console.WriteLine("{0,18} ------ ------", "------");
// These are valid conversions.
ConvertToAnyRadix(((System.UInt64 )(twoToThe32)), "Ra2");
ConvertToAnyRadix(((System.UInt64)(twoToThe32)), "Ra5");
ConvertToAnyRadix(((System.UInt64)(twoToThe32)), "Ra16");
ConvertToAnyRadix(((System.UInt64)(twoToThe32)), "Ra23");
ConvertToAnyRadix(((System.UInt64)(twoToThe32)), "Ra36");
ConvertToAnyRadix(((System.UInt64)(fifteenNines)), "Ra2");
ConvertToAnyRadix(((System.UInt64)(fifteenNines)), "Ra3");
ConvertToAnyRadix(((System.UInt64)(fifteenNines)), "Ra8");
ConvertToAnyRadix(((System.UInt64)(fifteenNines)), "Ra11");
ConvertToAnyRadix(((System.UInt64)(fifteenNines)), "Ra16");
ConvertToAnyRadix(((System.UInt64)(fifteenNines)), "Ra23");
ConvertToAnyRadix(((System.UInt64)(fifteenNines)), "Ra36");
ConvertToAnyRadix(((System.UInt64)(fifteenNines)), "E16");
ConvertToAnyRadix(((System.UInt64)(fifteenNines)), "");
// These are error conditions.
ConvertToAnyRadix(((System.UInt64)(fifteenNines)), "Ra37");
ConvertToAnyRadix("ABCDEFGHIJKLM", "Ra16");
} //main
} //IFormatProviderDemo
/*
This example of the IFormatProvider interface
and the IFormatProvider.GetFormat( Type ) method
generates the following output.
Number Format Result
------ ------ ------
4294967296 Ra2 100000000000000000000000000000000
4294967296 Ra5 32244002423141
4294967296 Ra16 100000000
4294967296 Ra23 1606K7IC
4294967296 Ra36 1Z141Z4
999999999999999 Ra2 11100011010111111010100100110001100111111111111111
999999999999999 Ra3 11212010201001210101011021212000
999999999999999 Ra8 34327724461477777
999999999999999 Ra11 26A6A3689065639
999999999999999 Ra16 38D7EA4C67FFF
999999999999999 Ra23 1134DIFHLMM4
999999999999999 Ra36 9UGXNORJLR
999999999999999 E16 9.9999999999999900E+014
999999999999999 999999999999999
999999999999999 Ra37 System.ArgumentException: The radix "37" is not in th
e range 2..36.
ABCDEFGHIJKLM Ra16 System.ArgumentException: The argument "ABCDEFGHIJKLM"
cannot be converted to an integer value. ---> System.FormatException: Input str
ing was not in a correct format.
*/
Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile für Pocket PC, Windows Mobile für Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
.NET Framework unterstützt nicht alle Versionen sämtlicher Plattformen. Eine Liste der unterstützten Versionen finden Sie unter Systemanforderungen.
