Common/src/org/apache/commons/codec/binary/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
 * 
 *      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 org.apache.commons.codec.CharEncoding;

/**
 * Converts String to and from bytes using the encodings required by the Java specification. These encodings are specified in <a
 * href="http://java.sun.com/j2se/1.4.2/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
 * 
 * @see CharEncoding
 * @see <a href="http://java.sun.com/j2se/1.4.2/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
 * @author <a href="mailto:ggregory@seagullsw.com">Gary Gregory</a>
 * @version $Id: StringUtils.java 801391 2009-08-05 19:55:54Z ggregory $
 * @since 1.4
 */
public class StringUtils {

    /**
     * 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
     * @return encoded bytes
     * @throws IllegalStateException
     *             Thrown when the charset is missing, which should be never according the the Java specification.
     * @see <a href="http://java.sun.com/j2se/1.4.2/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
     * @see #getBytesUnchecked(String, String)
     */
    public static byte[] getBytesIso8859_1(String string) {
        return StringUtils.getBytesUnchecked(string, CharEncoding.ISO_8859_1);
    }

    /**
     * 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
     * @return encoded bytes
     * @throws IllegalStateException
     *             Thrown when the charset is missing, which should be never according the the Java specification.
     * @see <a href="http://java.sun.com/j2se/1.4.2/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
     * @see #getBytesUnchecked(String, String)
     */
    public static byte[] getBytesUsAscii(String string) {
        return StringUtils.getBytesUnchecked(string, CharEncoding.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
     * @return encoded bytes
     * @throws IllegalStateException
     *             Thrown when the charset is missing, which should be never according the the Java specification.
     * @see <a href="http://java.sun.com/j2se/1.4.2/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
     * @see #getBytesUnchecked(String, String)
     */
    public static byte[] getBytesUtf16(String string) {
        return StringUtils.getBytesUnchecked(string, CharEncoding.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
     * @return encoded bytes
     * @throws IllegalStateException
     *             Thrown when the charset is missing, which should be never according the the Java specification.
     * @see <a href="http://java.sun.com/j2se/1.4.2/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
     * @see #getBytesUnchecked(String, String)
     */
    public static byte[] getBytesUtf16Be(String string) {
        return StringUtils.getBytesUnchecked(string, CharEncoding.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
     * @return encoded bytes
     * @throws IllegalStateException
     *             Thrown when the charset is missing, which should be never according the the Java specification.
     * @see <a href="http://java.sun.com/j2se/1.4.2/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
     * @see #getBytesUnchecked(String, String)
     */
    public static byte[] getBytesUtf16Le(String string) {
        return StringUtils.getBytesUnchecked(string, CharEncoding.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
     * @return encoded bytes
     * @throws IllegalStateException
     *             Thrown when the charset is missing, which should be never according the the Java specification.
     * @see <a href="http://java.sun.com/j2se/1.4.2/docs/api/java/nio/charset/Charset.html">Standard charsets</a>
     * @see #getBytesUnchecked(String, String)
     */
    public static byte[] getBytesUtf8(String string) {
        return StringUtils.getBytesUnchecked(string, CharEncoding.UTF_8);
    }

    /**
     * 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
     * @param charsetName
     *            The name of a required {@link java.nio.charset.Charset}
     * @return encoded bytes
     * @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(String string, String charsetName) {
        if (string == null) {
            return null;
        }
        try {
            return string.getBytes(charsetName);
        } catch (UnsupportedEncodingException e) {
            throw StringUtils.newIllegalStateException(charsetName, e);
        }
    }

    private static IllegalStateException newIllegalStateException(String charsetName, UnsupportedEncodingException e) {
        return new IllegalStateException(charsetName + ": " + e);
    }

    /**
     * Constructs a new <code>String</code> 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
     * @param charsetName
     *            The name of a required {@link java.nio.charset.Charset}
     * @return A new <code>String</code> decoded from the specified array of bytes using the given charset.
     * @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(byte[] bytes, String charsetName) {
        if (bytes == null) {
            return null;
        }
        try {
            return new String(bytes, charsetName);
        } catch (UnsupportedEncodingException e) {
            throw StringUtils.newIllegalStateException(charsetName, e);
        }
    }

    /**
     * Constructs a new <code>String</code> by decoding the specified array of bytes using the ISO-8859-1 charset.
     * 
     * @param bytes
     *            The bytes to be decoded into characters
     * @return A new <code>String</code> decoded from the specified array of bytes using the given charset.
     * @throws IllegalStateException
     *             Thrown when a {@link UnsupportedEncodingException} is caught, which should never happen since the
     *             charset is required.
     */
    public static String newStringIso8859_1(byte[] bytes) {
        return StringUtils.newString(bytes, CharEncoding.ISO_8859_1);
    }

    /**
     * Constructs a new <code>String</code> 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</code> decoded from the specified array of bytes using the given charset.
     * @throws IllegalStateException
     *             Thrown when a {@link UnsupportedEncodingException} is caught, which should never happen since the
     *             charset is required.
     */
    public static String newStringUsAscii(byte[] bytes) {
        return StringUtils.newString(bytes, CharEncoding.US_ASCII);
    }

    /**
     * Constructs a new <code>String</code> 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</code> decoded from the specified array of bytes using the given charset.
     * @throws IllegalStateException
     *             Thrown when a {@link UnsupportedEncodingException} is caught, which should never happen since the
     *             charset is required.
     */
    public static String newStringUtf16(byte[] bytes) {
        return StringUtils.newString(bytes, CharEncoding.UTF_16);
    }

    /**
     * Constructs a new <code>String</code> 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</code> decoded from the specified array of bytes using the given charset.
     * @throws IllegalStateException
     *             Thrown when a {@link UnsupportedEncodingException} is caught, which should never happen since the
     *             charset is required.
     */
    public static String newStringUtf16Be(byte[] bytes) {
        return StringUtils.newString(bytes, CharEncoding.UTF_16BE);
    }

    /**
     * Constructs a new <code>String</code> 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</code> decoded from the specified array of bytes using the given charset.
     * @throws IllegalStateException
     *             Thrown when a {@link UnsupportedEncodingException} is caught, which should never happen since the
     *             charset is required.
     */
    public static String newStringUtf16Le(byte[] bytes) {
        return StringUtils.newString(bytes, CharEncoding.UTF_16LE);
    }

    /**
     * Constructs a new <code>String</code> 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</code> decoded from the specified array of bytes using the given charset.
     * @throws IllegalStateException
     *             Thrown when a {@link UnsupportedEncodingException} is caught, which should never happen since the
     *             charset is required.
     */
    public static String newStringUtf8(byte[] bytes) {
        return StringUtils.newString(bytes, CharEncoding.UTF_8);
    }

}