StringUtils.java
/*
* 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
*
* https://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 java.nio.charset.StandardCharsets;
import org.apache.commons.codec.CharEncoding;
/**
* Converts String to and from bytes using the encodings required by the Java specification. These encodings are
* specified in standard {@link Charset}.
*
* <p>
* This class is immutable and thread-safe.
* </p>
*
* @see CharEncoding
* @see Charset
* @see StandardCharsets
* @since 1.4
*/
public class StringUtils {
/**
* <p>
* Compares two CharSequences, returning {@code true} if they represent equal sequences of characters.
* </p>
*
* <p>
* {@code null}s are handled without exceptions. Two {@code null} references are considered to be equal.
* The comparison is case sensitive.
* </p>
*
* <pre>
* 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
* </pre>
*
* <p>
* Copied from Apache Commons Lang r1583482 on April 10, 2014 (day of 3.3.2 release).
* </p>
*
* @see Object#equals(Object)
* @param cs1
* the first CharSequence, may be {@code null}
* @param cs2
* the second CharSequence, may be {@code null}
* @return {@code true} if the CharSequences are equal (case-sensitive), or both {@code 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 {@code 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 {@code null}
* @return encoded bytes, or {@code null} if the input string was {@code null}
* @throws NullPointerException
* Thrown if {@link StandardCharsets#UTF_8} is not initialized, which should never happen since it is
* required by the Java platform specification.
* @see Charset
* @see #getBytesUnchecked(String, String)
* @since 1.11
*/
public static ByteBuffer getByteBufferUtf8(final String string) {
return getByteBuffer(string, StandardCharsets.UTF_8);
}
/**
* Calls {@link String#getBytes(Charset)}
*
* @param string
* The string to encode (if null, return null).
* @param charset
* The {@link Charset} to encode the {@code String}
* @return the encoded bytes
*/
private static byte[] getBytes(final String string, final Charset charset) {
return string == null ? null : string.getBytes(charset);
}
/**
* 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 {@code null}
* @return encoded bytes, or {@code null} if the input string was {@code null}
* @throws NullPointerException
* Thrown if {@link StandardCharsets#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 Charset
* @see #getBytesUnchecked(String, String)
*/
public static byte[] getBytesIso8859_1(final String string) {
return getBytes(string, StandardCharsets.ISO_8859_1);
}
/**
* Encodes the given string into a sequence of bytes using the named charset, storing the result into a new byte
* array.
* <p>
* 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.
* </p>
*
* @param string
* the String to encode, may be {@code null}
* @param charsetName
* The name of a required {@link java.nio.charset.Charset}
* @return encoded bytes, or {@code null} if the input string was {@code 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 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 {@code null}
* @return encoded bytes, or {@code null} if the input string was {@code null}
* @throws NullPointerException
* Thrown if {@link StandardCharsets#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 Charset
* @see #getBytesUnchecked(String, String)
*/
public static byte[] getBytesUsAscii(final String string) {
return getBytes(string, StandardCharsets.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 {@code null}
* @return encoded bytes, or {@code null} if the input string was {@code null}
* @throws NullPointerException
* Thrown if {@link StandardCharsets#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 Charset
* @see #getBytesUnchecked(String, String)
*/
public static byte[] getBytesUtf16(final String string) {
return getBytes(string, StandardCharsets.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 {@code null}
* @return encoded bytes, or {@code null} if the input string was {@code null}
* @throws NullPointerException
* Thrown if {@link StandardCharsets#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 Charset
* @see #getBytesUnchecked(String, String)
*/
public static byte[] getBytesUtf16Be(final String string) {
return getBytes(string, StandardCharsets.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 {@code null}
* @return encoded bytes, or {@code null} if the input string was {@code null}
* @throws NullPointerException
* Thrown if {@link StandardCharsets#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 Charset
* @see #getBytesUnchecked(String, String)
*/
public static byte[] getBytesUtf16Le(final String string) {
return getBytes(string, StandardCharsets.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 {@code null}
* @return encoded bytes, or {@code null} if the input string was {@code null}
* @throws NullPointerException
* Thrown if {@link StandardCharsets#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 Charset
* @see #getBytesUnchecked(String, String)
*/
public static byte[] getBytesUtf8(final String string) {
return getBytes(string, StandardCharsets.UTF_8);
}
private static IllegalStateException newIllegalStateException(final String charsetName, final UnsupportedEncodingException e) {
return new IllegalStateException(charsetName + ": " + e);
}
/**
* Constructs a new {@code 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 {@code String}; not {@code null}
* @return A new {@code String} decoded from the specified array of bytes using the given charset,
* or {@code null} if the input byte array was {@code 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 {@code String} by decoding the specified array of bytes using the given charset.
* <p>
* 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.
* </p>
*
* @param bytes
* The bytes to be decoded into characters, may be {@code null}
* @param charsetName
* The name of a required {@link java.nio.charset.Charset}
* @return A new {@code String} decoded from the specified array of bytes using the given charset,
* or {@code null} if the input byte array was {@code 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 newIllegalStateException(charsetName, e);
}
}
/**
* Constructs a new {@code 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 {@code null}
* @return A new {@code String} decoded from the specified array of bytes using the ISO-8859-1 charset, or
* {@code null} if the input byte array was {@code null}.
* @throws NullPointerException
* Thrown if {@link StandardCharsets#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, StandardCharsets.ISO_8859_1);
}
/**
* Constructs a new {@code 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 {@code String} decoded from the specified array of bytes using the US-ASCII charset,
* or {@code null} if the input byte array was {@code null}.
* @throws NullPointerException
* Thrown if {@link StandardCharsets#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, StandardCharsets.US_ASCII);
}
/**
* Constructs a new {@code 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 {@code String} decoded from the specified array of bytes using the UTF-16 charset
* or {@code null} if the input byte array was {@code null}.
* @throws NullPointerException
* Thrown if {@link StandardCharsets#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, StandardCharsets.UTF_16);
}
/**
* Constructs a new {@code 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 {@code String} decoded from the specified array of bytes using the UTF-16BE charset,
* or {@code null} if the input byte array was {@code null}.
* @throws NullPointerException
* Thrown if {@link StandardCharsets#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, StandardCharsets.UTF_16BE);
}
/**
* Constructs a new {@code 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 {@code String} decoded from the specified array of bytes using the UTF-16LE charset,
* or {@code null} if the input byte array was {@code null}.
* @throws NullPointerException
* Thrown if {@link StandardCharsets#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, StandardCharsets.UTF_16LE);
}
/**
* Constructs a new {@code 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 {@code String} decoded from the specified array of bytes using the UTF-8 charset,
* or {@code null} if the input byte array was {@code null}.
* @throws NullPointerException
* Thrown if {@link StandardCharsets#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, StandardCharsets.UTF_8);
}
/**
* TODO Make private in 2.0.
*
* @deprecated TODO Make private in 2.0.
*/
@Deprecated
public StringUtils() {
// empty
}
}