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Commons Codec example source code file (StringUtils.java)

This example Commons Codec source code file (StringUtils.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Commons Codec tags/keywords

illegalstateexception, illegalstateexception, io, string, string, stringutils, stringutils, unsupportedencodingexception, unsupportedencodingexception

The Commons Codec StringUtils.java source code

/*
 * 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
 * @author <a href="mailto:ggregory@seagullsw.com">Gary Gregory
 * @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
     * @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
     * @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
     * @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
     * @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
     * @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
     * @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 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 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 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 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 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 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 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 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 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 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 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 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 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 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);
    }

}

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