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Java 1.8+ Library with tons of utility classes required in all projects
/*
* Copyright (C) 2014-2022 Philip Helger (www.helger.com)
* philip[at]helger[dot]com
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.helger.commons.charset;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UncheckedIOException;
import java.nio.charset.Charset;
import java.nio.charset.IllegalCharsetNameException;
import java.nio.charset.UnsupportedCharsetException;
import java.util.SortedMap;
import javax.annotation.Nonnegative;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import javax.annotation.WillNotClose;
import javax.annotation.concurrent.Immutable;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.helger.commons.ValueEnforcer;
import com.helger.commons.annotation.CodingStyleguideUnaware;
import com.helger.commons.annotation.Nonempty;
import com.helger.commons.annotation.PresentForCodeCoverage;
import com.helger.commons.annotation.ReturnsMutableCopy;
import com.helger.commons.collection.ArrayHelper;
import com.helger.commons.collection.impl.CommonsLinkedHashMap;
import com.helger.commons.collection.impl.ICommonsOrderedMap;
import com.helger.commons.io.IHasInputStream;
import com.helger.commons.io.stream.NonBlockingPushbackInputStream;
import com.helger.commons.io.stream.StreamHelper;
import com.helger.commons.string.StringHelper;
/**
* Whole lotta charset management routines.
*
* @author Philip Helger
*/
@Immutable
public final class CharsetHelper
{
private static final Logger LOGGER = LoggerFactory.getLogger (CharsetHelper.class);
@CodingStyleguideUnaware
private static final SortedMap ALL_CHARSETS;
static
{
// Returns an immutable object
ALL_CHARSETS = Charset.availableCharsets ();
}
@PresentForCodeCoverage
private static final CharsetHelper INSTANCE = new CharsetHelper ();
private CharsetHelper ()
{}
/**
* Resolve the charset by the specified name. The difference to
* {@link Charset#forName(String)} is, that this method has no checked
* exceptions but only unchecked exceptions.
*
* @param sCharsetName
* The charset to be resolved. May neither be null nor
* empty.
* @return The Charset object
* @throws IllegalArgumentException
* If the charset could not be resolved.
*/
@Nonnull
public static Charset getCharsetFromName (@Nonnull @Nonempty final String sCharsetName)
{
ValueEnforcer.notNull (sCharsetName, "CharsetName");
try
{
return Charset.forName (sCharsetName);
}
catch (final IllegalCharsetNameException ex)
{
// Not supported in any version
throw new IllegalArgumentException ("Charset '" + sCharsetName + "' unsupported in Java", ex);
}
catch (final UnsupportedCharsetException ex)
{
// Unsupported on this platform
throw new IllegalArgumentException ("Charset '" + sCharsetName + "' unsupported on this platform", ex);
}
}
/**
* Resolve the charset by the specified name. The difference to
* {@link Charset#forName(String)} is, that this method throws no exceptions.
*
* @param sCharsetName
* The charset to be resolved. May be null or empty.
* @return The Charset object or null if no such charset was
* found.
*/
@Nullable
public static Charset getCharsetFromNameOrNull (@Nullable final String sCharsetName)
{
return getCharsetFromNameOrDefault (sCharsetName, null);
}
/**
* Resolve the charset by the specified name. The difference to
* {@link Charset#forName(String)} is, that this method throws no exceptions.
*
* @param sCharsetName
* The charset to be resolved. May be null or empty.
* @param aDefault
* the default charset to be returned if none is provided. May be
* null.
* @return The Charset object or the provided default if no such charset was
* found.
*/
@Nullable
public static Charset getCharsetFromNameOrDefault (@Nullable final String sCharsetName, @Nullable final Charset aDefault)
{
if (StringHelper.hasText (sCharsetName))
try
{
return getCharsetFromName (sCharsetName);
}
catch (final IllegalArgumentException ex)
{
// Fall through
}
return aDefault;
}
/**
* @return An immutable collection of all available charsets from the standard
* charset provider.
*/
@Nonnull
@ReturnsMutableCopy
public static ICommonsOrderedMap getAllCharsets ()
{
return new CommonsLinkedHashMap <> (ALL_CHARSETS);
}
@Nullable
public static String getAsStringInOtherCharset (@Nullable final String sText,
@Nonnull final Charset aCurrentCharset,
@Nonnull final Charset aNewCharset)
{
ValueEnforcer.notNull (aCurrentCharset, "CurrentCharset");
ValueEnforcer.notNull (aNewCharset, "NewCharset");
if (sText == null || aCurrentCharset.equals (aNewCharset))
return sText;
return new String (sText.getBytes (aCurrentCharset), aNewCharset);
}
/**
* Get the number of bytes necessary to represent the passed string as an
* UTF-8 string.
*
* @param s
* The string to count the length. May be null or empty.
* @return A non-negative value.
*/
@Nonnegative
public static int getUTF8ByteCount (@Nullable final String s)
{
return s == null ? 0 : getUTF8ByteCount (s.toCharArray ());
}
/**
* Get the number of bytes necessary to represent the passed char array as an
* UTF-8 string.
*
* @param aChars
* The characters to count the length. May be null or
* empty.
* @return A non-negative value.
*/
@Nonnegative
public static int getUTF8ByteCount (@Nullable final char [] aChars)
{
int nCount = 0;
if (aChars != null)
for (final char c : aChars)
nCount += getUTF8ByteCount (c);
return nCount;
}
@Nonnegative
public static int getUTF8ByteCount (final char c)
{
return getUTF8ByteCount ((int) c);
}
/**
* Get the number of bytes necessary to represent the passed character.
*
* @param c
* The character to be evaluated.
* @return A non-negative value.
*/
@Nonnegative
public static int getUTF8ByteCount (@Nonnegative final int c)
{
ValueEnforcer.isBetweenInclusive (c, "c", Character.MIN_VALUE, Character.MAX_VALUE);
// see JVM spec 4.4.7, p 111
// http://java.sun.com/docs/books/jvms/second_edition/html/ClassFile.doc.html
// #1297
if (c == 0)
return 2;
// Source: http://icu-project.org/apiref/icu4c/utf8_8h_source.html
if (c <= 0x7f)
return 1;
if (c <= 0x7ff)
return 2;
if (c <= 0xd7ff)
return 3;
// It's a surrogate...
return 0;
}
/**
* A wrapper that has an {@link InputStream}, an optional Unicode BOM as
* {@link EUnicodeBOM} and an optional {@link Charset}.
*
* @author Philip Helger
*/
public static final class InputStreamAndCharset implements IHasInputStream
{
private final InputStream m_aIS;
private final EUnicodeBOM m_eBOM;
private final Charset m_aCharset;
public InputStreamAndCharset (@Nonnull final InputStream aIS, @Nullable final EUnicodeBOM eBOM, @Nullable final Charset aCharset)
{
m_aIS = aIS;
m_eBOM = eBOM;
m_aCharset = aCharset;
}
@Nonnull
public InputStream getInputStream ()
{
return m_aIS;
}
public boolean isReadMultiple ()
{
return false;
}
@Nullable
public EUnicodeBOM getBOM ()
{
return m_eBOM;
}
public boolean hasBOM ()
{
return m_eBOM != null;
}
@Nullable
public Charset getCharset ()
{
return m_aCharset;
}
public boolean hasCharset ()
{
return m_aCharset != null;
}
@Nullable
public Charset getCharset (@Nullable final Charset aFallbackCharset)
{
return m_aCharset != null ? m_aCharset : aFallbackCharset;
}
}
/**
* If a BOM is present in the {@link InputStream} it is read and if possible
* the charset is automatically determined from the BOM.
*
* @param aIS
* The input stream to use. May not be null.
* @return Never null. Always use the input stream contained in
* the returned object and never the one passed in as a parameter,
* because the returned IS is a push-back InputStream that has a
* couple of bytes already buffered!
*/
@Nonnull
public static InputStreamAndCharset getInputStreamAndCharsetFromBOM (@Nonnull @WillNotClose final InputStream aIS)
{
ValueEnforcer.notNull (aIS, "InputStream");
// Check for BOM
final int nMaxBOMBytes = EUnicodeBOM.getMaximumByteCount ();
@WillNotClose
final NonBlockingPushbackInputStream aPIS = new NonBlockingPushbackInputStream (StreamHelper.getBuffered (aIS), nMaxBOMBytes);
try
{
// Try to read as many bytes as necessary to determine all supported BOMs
final byte [] aBOM = new byte [nMaxBOMBytes];
final int nReadBOMBytes = aPIS.read (aBOM);
EUnicodeBOM eBOM = null;
Charset aDeterminedCharset = null;
if (nReadBOMBytes > 0)
{
// Some byte BOMs were read - determine
eBOM = EUnicodeBOM.getFromBytesOrNull (ArrayHelper.getCopy (aBOM, 0, nReadBOMBytes));
if (eBOM == null)
{
// Unread the whole BOM
aPIS.unread (aBOM, 0, nReadBOMBytes);
// aDeterminedCharset stays null
}
else
{
if (LOGGER.isDebugEnabled ())
LOGGER.debug ("Found " + eBOM + " on " + aIS.getClass ().getName ());
// Unread the unnecessary parts of the BOM
final int nBOMBytes = eBOM.getByteCount ();
if (nBOMBytes < nReadBOMBytes)
aPIS.unread (aBOM, nBOMBytes, nReadBOMBytes - nBOMBytes);
// Use the Charset of the BOM - maybe null!
aDeterminedCharset = eBOM.getCharset ();
}
}
return new InputStreamAndCharset (aPIS, eBOM, aDeterminedCharset);
}
catch (final IOException ex)
{
LOGGER.error ("Failed to determine BOM", ex);
StreamHelper.close (aPIS);
throw new UncheckedIOException (ex);
}
}
@Nonnull
public static InputStreamReader getReaderByBOM (@Nonnull final InputStream aIS, @Nonnull final Charset aFallbackCharset)
{
ValueEnforcer.notNull (aIS, "InputStream");
ValueEnforcer.notNull (aFallbackCharset, "FallbackCharset");
// Determine BOM/Charset
final InputStreamAndCharset aISAndBOM = getInputStreamAndCharsetFromBOM (aIS);
// Create the reader with the current position of the InputStream and the
// correct charset
final Charset aEffectiveCharset = aISAndBOM.getCharset (aFallbackCharset);
return StreamHelper.createReader (aISAndBOM.getInputStream (), aEffectiveCharset);
}
}