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Java 1.8+ Library with tons of utility classes required in all projects
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/*
* Copyright (C) 2014-2024 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.nio.charset.Charset;
import javax.annotation.Nonnegative;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import com.helger.commons.ValueEnforcer;
import com.helger.commons.annotation.Nonempty;
import com.helger.commons.annotation.ReturnsMutableCopy;
import com.helger.commons.collection.ArrayHelper;
import com.helger.commons.io.ByteArrayWrapper;
/**
* Defines the most common Byte Order Markers for Unicode encoded text files.
*
* Source: http://de.wikipedia.org/wiki/Byte_Order_Mark
* Important: BOMS with more bytes should come first to avoid wrong detections.
*
* Note: SCSU = A Standard Compression Scheme for Unicode:
* http://www.unicode.org/reports/tr6/
* Note: BOCU = Binary Ordered Compression for Unicode
*
* @author Philip Helger
*/
public enum EUnicodeBOM
{
// 4 bytes
/** UTF-32 Big Endian */
BOM_UTF_32_BIG_ENDIAN (new byte [] { 0x00, 0x00, (byte) 0xfe, (byte) 0xff }, "utf-32be"),
/** UTF-32 Little Endian */
BOM_UTF_32_LITTLE_ENDIAN (new byte [] { (byte) 0xff, (byte) 0xfe, 0x00, 0x00 }, "utf-32le"),
/** UTF-7 */
BOM_UTF_7 (new byte [] { 0x2b, 0x2f, 0x76, 0x38 }, "utf-7"),
/** UTF-7 */
BOM_UTF_7_ALT2 (new byte [] { 0x2b, 0x2f, 0x76, 0x39 }, "utf-7"),
/** UTF-7 */
BOM_UTF_7_ALT3 (new byte [] { 0x2b, 0x2f, 0x76, 0x2b }, "utf-7"),
/** UTF-7 */
BOM_UTF_7_ALT4 (new byte [] { 0x2b, 0x2f, 0x76, 0x2f }, "utf-7"),
/** UTF-EBCDIC */
BOM_UTF_EBCDIC (new byte [] { (byte) 0xdd, 0x73, 0x66, 0x73 }, null),
/** BOCU */
BOM_BOCU_1_ALT2 (new byte [] { (byte) 0xfb, (byte) 0xee, 0x28, (byte) 0xff }, null),
/** GB 18030 */
BOM_GB_18030 (new byte [] { (byte) 0x84, 0x31, (byte) 0x95, 0x33 }, "gb18030"),
// 3 bytes
/** UTF-8 */
BOM_UTF_8 (new byte [] { (byte) 0xef, (byte) 0xbb, (byte) 0xbf }, "utf-8"),
/** UTF-1 */
BOM_UTF_1 (new byte [] { (byte) 0xf7, 0x64, 0x4c }, "utf-1"),
/** BOCU */
BOM_BOCU_1 (new byte [] { (byte) 0xfb, (byte) 0xee, 0x28 }, null),
/** SCSU - Single-byte mode Quote Unicode */
BOM_SCSU (new byte [] { 0x0e, (byte) 0xfe, (byte) 0xff }, null),
/** SCSU - Single-byte mode Change to Unicode */
BOM_SCSU_TO_UCS (new byte [] { 0x0f, (byte) 0xfe, (byte) 0xff }, null),
/** SCSU - Single-byte mode Define dynamic window 0 to 0xFE80 */
BOM_SCSU_W0_TO_FE80 (new byte [] { 0x18, (byte) 0xa5, (byte) 0xff }, null),
/** SCSU - Single-byte mode Define dynamic window 1 to 0xFE80 */
BOM_SCSU_W1_TO_FE80 (new byte [] { 0x19, (byte) 0xa5, (byte) 0xff }, null),
/** SCSU - Single-byte mode Define dynamic window 2 to 0xFE80 */
BOM_SCSU_W2_TO_FE80 (new byte [] { 0x1a, (byte) 0xa5, (byte) 0xff }, null),
/** SCSU - Single-byte mode Define dynamic window 3 to 0xFE80 */
BOM_SCSU_W3_TO_FE80 (new byte [] { 0x1b, (byte) 0xa5, (byte) 0xff }, null),
/** SCSU - Single-byte mode Define dynamic window 4 to 0xFE80 */
BOM_SCSU_W4_TO_FE80 (new byte [] { 0x1c, (byte) 0xa5, (byte) 0xff }, null),
/** SCSU - Single-byte mode Define dynamic window 5 to 0xFE80 */
BOM_SCSU_W5_TO_FE80 (new byte [] { 0x1d, (byte) 0xa5, (byte) 0xff }, null),
/** SCSU - Single-byte mode Define dynamic window 6 to 0xFE80 */
BOM_SCSU_W6_TO_FE80 (new byte [] { 0x1e, (byte) 0xa5, (byte) 0xff }, null),
/** SCSU - Single-byte mode Define dynamic window 7 to 0xFE80 */
BOM_SCSU_W7_TO_FE80 (new byte [] { 0x1f, (byte) 0xa5, (byte) 0xff }, null),
// 2 bytes
/** UTF-16 Big Endian */
BOM_UTF_16_BIG_ENDIAN (new byte [] { (byte) 0xfe, (byte) 0xff }, "utf-16be"),
/** UTF-16 Little Endian */
BOM_UTF_16_LITTLE_ENDIAN (new byte [] { (byte) 0xff, (byte) 0xfe }, "utf-16le");
private static final int MAXIMUM_BOM_BYTE_COUNT = 4;
private final ByteArrayWrapper m_aBOMBytes;
private final String m_sCharsetName;
private final Charset m_aCharset;
EUnicodeBOM (@Nonnull @Nonempty final byte [] aBytes, @Nullable final String sCharset)
{
ValueEnforcer.isBetweenInclusive (aBytes.length, "Byte count", 1, MAXIMUM_BOM_BYTE_COUNT);
m_aBOMBytes = new ByteArrayWrapper (aBytes, false);
m_sCharsetName = sCharset;
m_aCharset = CharsetHelper.getCharsetFromNameOrNull (sCharset);
}
/**
* @return A copy of the byte array that identifies this BOM.
*/
@Nonnull
@Nonempty
@ReturnsMutableCopy
public byte [] getAllBytes ()
{
return m_aBOMBytes.getAllBytes ();
}
/**
* @return The number of bytes defining this BOM
*/
@Nonnegative
public int getByteCount ()
{
return m_aBOMBytes.size ();
}
/**
* Check if the passed byte array starts with this BOM's bytes.
*
* @param aBytes
* The byte array to search for a BOM. May be null or
* empty.
* @return true if the passed byte array starts with this BOM,
* false otherwise.
*/
public boolean isPresent (@Nullable final byte [] aBytes)
{
if (aBytes == null)
return false;
return ArrayHelper.startsWith (aBytes, m_aBOMBytes.bytes ());
}
/**
* @return The name of the charset. This may be null if no known
* charset exists for Java. This string may be present, even if
* {@link #getCharset()} returns null. To support e.g.
* "utf-7" you need to add additional JAR files.
*/
@Nullable
public String getCharsetName ()
{
return m_sCharsetName;
}
/**
* @return The charset matching this BOM. May be null if the
* charset is not part of the Sun JDK or there is not even a defined
* charset.
*/
@Nullable
public Charset getCharset ()
{
return m_aCharset;
}
/**
* @return true if this BOM has an assigned charset,
* false if not.
* @see #getCharset()
* @since 9.0.0
*/
public boolean hasCharset ()
{
return m_aCharset != null;
}
/**
* @return The maximum number of bytes a BOM may have.
*/
@Nonnegative
public static int getMaximumByteCount ()
{
return MAXIMUM_BOM_BYTE_COUNT;
}
/**
* Find the BOM that is matching the passed byte array.
*
* @param aBytes
* The bytes to be checked for the BOM. May be null. To
* check all BOMs, this array must have at least 4 (=
* {@link #getMaximumByteCount()}) bytes.
* @return null if the passed bytes do not resemble a BOM.
*/
@Nullable
public static EUnicodeBOM getFromBytesOrNull (@Nullable final byte [] aBytes)
{
if (ArrayHelper.isNotEmpty (aBytes))
for (final EUnicodeBOM eBOM : values ())
if (eBOM.isPresent (aBytes))
return eBOM;
return null;
}
}