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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.commons.codec.binary;

import java.io.UnsupportedEncodingException;
import java.nio.ByteBuffer;
import java.nio.charset.Charset;

import org.apache.commons.codec.CharEncoding;
import org.apache.commons.codec.Charsets;

/**
 * Converts String to and from bytes using the encodings required by the Java specification. These encodings are
 * specified in 
 * Standard charsets.
 *
 * 

This class is immutable and thread-safe.

* * @see CharEncoding * @see Standard charsets * @version $Id$ * @since 1.4 */ public class StringUtils { /** *

* Compares two CharSequences, returning true if they represent equal sequences of characters. *

* *

* nulls are handled without exceptions. Two null references are considered to be equal. * The comparison is case sensitive. *

* *
     * StringUtils.equals(null, null)   = true
     * StringUtils.equals(null, "abc")  = false
     * StringUtils.equals("abc", null)  = false
     * StringUtils.equals("abc", "abc") = true
     * StringUtils.equals("abc", "ABC") = false
     * 
* *

* Copied from Apache Commons Lang r1583482 on April 10, 2014 (day of 3.3.2 release). *

* * @see Object#equals(Object) * @param cs1 * the first CharSequence, may be null * @param cs2 * the second CharSequence, may be null * @return true if the CharSequences are equal (case-sensitive), or both null * @since 1.10 */ public static boolean equals(final CharSequence cs1, final CharSequence cs2) { if (cs1 == cs2) { return true; } if (cs1 == null || cs2 == null) { return false; } if (cs1 instanceof String && cs2 instanceof String) { return cs1.equals(cs2); } return cs1.length() == cs2.length() && CharSequenceUtils.regionMatches(cs1, false, 0, cs2, 0, cs1.length()); } /** * Calls {@link String#getBytes(Charset)} * * @param string * The string to encode (if null, return null). * @param charset * The {@link Charset} to encode the String * @return the encoded bytes */ private static byte[] getBytes(final String string, final Charset charset) { if (string == null) { return null; } return string.getBytes(charset); } /** * Calls {@link String#getBytes(Charset)} * * @param string * The string to encode (if null, return null). * @param charset * The {@link Charset} to encode the String * @return the encoded bytes */ private static ByteBuffer getByteBuffer(final String string, final Charset charset) { if (string == null) { return null; } return ByteBuffer.wrap(string.getBytes(charset)); } /** * Encodes the given string into a byte buffer using the UTF-8 charset, storing the result into a new byte * array. * * @param string * the String to encode, may be null * @return encoded bytes, or null if the input string was null * @throws NullPointerException * Thrown if {@link Charsets#UTF_8} is not initialized, which should never happen since it is * required by the Java platform specification. * @see Standard charsets * @see #getBytesUnchecked(String, String) * @since 1.11 */ public static ByteBuffer getByteBufferUtf8(final String string) { return getByteBuffer(string, Charsets.UTF_8); } /** * Encodes the given string into a sequence of bytes using the ISO-8859-1 charset, storing the result into a new * byte array. * * @param string * the String to encode, may be null * @return encoded bytes, or null if the input string was null * @throws NullPointerException * Thrown if {@link Charsets#ISO_8859_1} is not initialized, which should never happen since it is * required by the Java platform specification. * @since As of 1.7, throws {@link NullPointerException} instead of UnsupportedEncodingException * @see Standard charsets * @see #getBytesUnchecked(String, String) */ public static byte[] getBytesIso8859_1(final String string) { return getBytes(string, Charsets.ISO_8859_1); } /** * Encodes the given string into a sequence of bytes using the named charset, storing the result into a new byte * array. *

* This method catches {@link UnsupportedEncodingException} and rethrows it as {@link IllegalStateException}, which * should never happen for a required charset name. Use this method when the encoding is required to be in the JRE. *

* * @param string * the String to encode, may be null * @param charsetName * The name of a required {@link java.nio.charset.Charset} * @return encoded bytes, or null if the input string was null * @throws IllegalStateException * Thrown when a {@link UnsupportedEncodingException} is caught, which should never happen for a * required charset name. * @see CharEncoding * @see String#getBytes(String) */ public static byte[] getBytesUnchecked(final String string, final String charsetName) { if (string == null) { return null; } try { return string.getBytes(charsetName); } catch (final UnsupportedEncodingException e) { throw StringUtils.newIllegalStateException(charsetName, e); } } /** * Encodes the given string into a sequence of bytes using the US-ASCII charset, storing the result into a new byte * array. * * @param string * the String to encode, may be null * @return encoded bytes, or null if the input string was null * @throws NullPointerException * Thrown if {@link Charsets#US_ASCII} is not initialized, which should never happen since it is * required by the Java platform specification. * @since As of 1.7, throws {@link NullPointerException} instead of UnsupportedEncodingException * @see Standard charsets * @see #getBytesUnchecked(String, String) */ public static byte[] getBytesUsAscii(final String string) { return getBytes(string, Charsets.US_ASCII); } /** * Encodes the given string into a sequence of bytes using the UTF-16 charset, storing the result into a new byte * array. * * @param string * the String to encode, may be null * @return encoded bytes, or null if the input string was null * @throws NullPointerException * Thrown if {@link Charsets#UTF_16} is not initialized, which should never happen since it is * required by the Java platform specification. * @since As of 1.7, throws {@link NullPointerException} instead of UnsupportedEncodingException * @see Standard charsets * @see #getBytesUnchecked(String, String) */ public static byte[] getBytesUtf16(final String string) { return getBytes(string, Charsets.UTF_16); } /** * Encodes the given string into a sequence of bytes using the UTF-16BE charset, storing the result into a new byte * array. * * @param string * the String to encode, may be null * @return encoded bytes, or null if the input string was null * @throws NullPointerException * Thrown if {@link Charsets#UTF_16BE} is not initialized, which should never happen since it is * required by the Java platform specification. * @since As of 1.7, throws {@link NullPointerException} instead of UnsupportedEncodingException * @see Standard charsets * @see #getBytesUnchecked(String, String) */ public static byte[] getBytesUtf16Be(final String string) { return getBytes(string, Charsets.UTF_16BE); } /** * Encodes the given string into a sequence of bytes using the UTF-16LE charset, storing the result into a new byte * array. * * @param string * the String to encode, may be null * @return encoded bytes, or null if the input string was null * @throws NullPointerException * Thrown if {@link Charsets#UTF_16LE} is not initialized, which should never happen since it is * required by the Java platform specification. * @since As of 1.7, throws {@link NullPointerException} instead of UnsupportedEncodingException * @see Standard charsets * @see #getBytesUnchecked(String, String) */ public static byte[] getBytesUtf16Le(final String string) { return getBytes(string, Charsets.UTF_16LE); } /** * Encodes the given string into a sequence of bytes using the UTF-8 charset, storing the result into a new byte * array. * * @param string * the String to encode, may be null * @return encoded bytes, or null if the input string was null * @throws NullPointerException * Thrown if {@link Charsets#UTF_8} is not initialized, which should never happen since it is * required by the Java platform specification. * @since As of 1.7, throws {@link NullPointerException} instead of UnsupportedEncodingException * @see Standard charsets * @see #getBytesUnchecked(String, String) */ public static byte[] getBytesUtf8(final String string) { return getBytes(string, Charsets.UTF_8); } private static IllegalStateException newIllegalStateException(final String charsetName, final UnsupportedEncodingException e) { return new IllegalStateException(charsetName + ": " + e); } /** * Constructs a new String by decoding the specified array of bytes using the given charset. * * @param bytes * The bytes to be decoded into characters * @param charset * The {@link Charset} to encode the String; not {@code null} * @return A new String decoded from the specified array of bytes using the given charset, * or null if the input byte array was null. * @throws NullPointerException * Thrown if charset is {@code null} */ private static String newString(final byte[] bytes, final Charset charset) { return bytes == null ? null : new String(bytes, charset); } /** * Constructs a new String by decoding the specified array of bytes using the given charset. *

* This method catches {@link UnsupportedEncodingException} and re-throws it as {@link IllegalStateException}, which * should never happen for a required charset name. Use this method when the encoding is required to be in the JRE. *

* * @param bytes * The bytes to be decoded into characters, may be null * @param charsetName * The name of a required {@link java.nio.charset.Charset} * @return A new String decoded from the specified array of bytes using the given charset, * or null if the input byte array was null. * @throws IllegalStateException * Thrown when a {@link UnsupportedEncodingException} is caught, which should never happen for a * required charset name. * @see CharEncoding * @see String#String(byte[], String) */ public static String newString(final byte[] bytes, final String charsetName) { if (bytes == null) { return null; } try { return new String(bytes, charsetName); } catch (final UnsupportedEncodingException e) { throw StringUtils.newIllegalStateException(charsetName, e); } } /** * Constructs a new String by decoding the specified array of bytes using the ISO-8859-1 charset. * * @param bytes * The bytes to be decoded into characters, may be null * @return A new String decoded from the specified array of bytes using the ISO-8859-1 charset, or * null if the input byte array was null. * @throws NullPointerException * Thrown if {@link Charsets#ISO_8859_1} is not initialized, which should never happen since it is * required by the Java platform specification. * @since As of 1.7, throws {@link NullPointerException} instead of UnsupportedEncodingException */ public static String newStringIso8859_1(final byte[] bytes) { return newString(bytes, Charsets.ISO_8859_1); } /** * Constructs a new String by decoding the specified array of bytes using the US-ASCII charset. * * @param bytes * The bytes to be decoded into characters * @return A new String decoded from the specified array of bytes using the US-ASCII charset, * or null if the input byte array was null. * @throws NullPointerException * Thrown if {@link Charsets#US_ASCII} is not initialized, which should never happen since it is * required by the Java platform specification. * @since As of 1.7, throws {@link NullPointerException} instead of UnsupportedEncodingException */ public static String newStringUsAscii(final byte[] bytes) { return newString(bytes, Charsets.US_ASCII); } /** * Constructs a new String by decoding the specified array of bytes using the UTF-16 charset. * * @param bytes * The bytes to be decoded into characters * @return A new String decoded from the specified array of bytes using the UTF-16 charset * or null if the input byte array was null. * @throws NullPointerException * Thrown if {@link Charsets#UTF_16} is not initialized, which should never happen since it is * required by the Java platform specification. * @since As of 1.7, throws {@link NullPointerException} instead of UnsupportedEncodingException */ public static String newStringUtf16(final byte[] bytes) { return newString(bytes, Charsets.UTF_16); } /** * Constructs a new String by decoding the specified array of bytes using the UTF-16BE charset. * * @param bytes * The bytes to be decoded into characters * @return A new String decoded from the specified array of bytes using the UTF-16BE charset, * or null if the input byte array was null. * @throws NullPointerException * Thrown if {@link Charsets#UTF_16BE} is not initialized, which should never happen since it is * required by the Java platform specification. * @since As of 1.7, throws {@link NullPointerException} instead of UnsupportedEncodingException */ public static String newStringUtf16Be(final byte[] bytes) { return newString(bytes, Charsets.UTF_16BE); } /** * Constructs a new String by decoding the specified array of bytes using the UTF-16LE charset. * * @param bytes * The bytes to be decoded into characters * @return A new String decoded from the specified array of bytes using the UTF-16LE charset, * or null if the input byte array was null. * @throws NullPointerException * Thrown if {@link Charsets#UTF_16LE} is not initialized, which should never happen since it is * required by the Java platform specification. * @since As of 1.7, throws {@link NullPointerException} instead of UnsupportedEncodingException */ public static String newStringUtf16Le(final byte[] bytes) { return newString(bytes, Charsets.UTF_16LE); } /** * Constructs a new String by decoding the specified array of bytes using the UTF-8 charset. * * @param bytes * The bytes to be decoded into characters * @return A new String decoded from the specified array of bytes using the UTF-8 charset, * or null if the input byte array was null. * @throws NullPointerException * Thrown if {@link Charsets#UTF_8} is not initialized, which should never happen since it is * required by the Java platform specification. * @since As of 1.7, throws {@link NullPointerException} instead of UnsupportedEncodingException */ public static String newStringUtf8(final byte[] bytes) { return newString(bytes, Charsets.UTF_8); } }




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