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/*
 * Copyright 2002-2015 the original author or authors.
 *
 * 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 org.springframework.util;

import java.nio.charset.Charset;
import java.util.Base64;
import javax.xml.bind.DatatypeConverter;

import org.springframework.lang.UsesJava8;

/**
 * A simple utility class for Base64 encoding and decoding.
 *
 * 

Adapts to either Java 8's {@link java.util.Base64} class or Apache Commons Codec's * {@link org.apache.commons.codec.binary.Base64} class. With neither Java 8 nor Commons * Codec present, {@link #encode}/{@link #decode} calls will throw an IllegalStateException. * However, as of Spring 4.2, {@link #encodeToString} and {@link #decodeFromString} will * nevertheless work since they can delegate to the JAXB DatatypeConverter as a fallback. * * @author Juergen Hoeller * @since 4.1 * @see java.util.Base64 * @see org.apache.commons.codec.binary.Base64 * @see javax.xml.bind.DatatypeConverter#printBase64Binary * @see javax.xml.bind.DatatypeConverter#parseBase64Binary */ public abstract class Base64Utils { private static final Charset DEFAULT_CHARSET = Charset.forName("UTF-8"); private static final Base64Delegate delegate; static { Base64Delegate delegateToUse = null; // JDK 8's java.util.Base64 class present? if (ClassUtils.isPresent("java.util.Base64", Base64Utils.class.getClassLoader())) { delegateToUse = new JdkBase64Delegate(); } // Apache Commons Codec present on the classpath? else if (ClassUtils.isPresent("org.apache.commons.codec.binary.Base64", Base64Utils.class.getClassLoader())) { delegateToUse = new CommonsCodecBase64Delegate(); } delegate = delegateToUse; } /** * Assert that Byte64 encoding between byte arrays is actually supported. * @throws IllegalStateException if neither Java 8 nor Apache Commons Codec is present */ private static void assertDelegateAvailable() { Assert.state(delegate != null, "Neither Java 8 nor Apache Commons Codec found - Base64 encoding between byte arrays not supported"); } /** * Base64-encode the given byte array. * @param src the original byte array (may be {@code null}) * @return the encoded byte array (or {@code null} if the input was {@code null}) * @throws IllegalStateException if Base64 encoding between byte arrays is not * supported, i.e. neither Java 8 nor Apache Commons Codec is present at runtime */ public static byte[] encode(byte[] src) { assertDelegateAvailable(); return delegate.encode(src); } /** * Base64-decode the given byte array. * @param src the encoded byte array (may be {@code null}) * @return the original byte array (or {@code null} if the input was {@code null}) * @throws IllegalStateException if Base64 encoding between byte arrays is not * supported, i.e. neither Java 8 nor Apache Commons Codec is present at runtime */ public static byte[] decode(byte[] src) { assertDelegateAvailable(); return delegate.decode(src); } /** * Base64-encode the given byte array to a String. * @param src the original byte array (may be {@code null}) * @return the encoded byte array as a UTF-8 String * (or {@code null} if the input was {@code null}) */ public static String encodeToString(byte[] src) { if (src == null) { return null; } if (src.length == 0) { return ""; } if (delegate != null) { // Full encoder available return new String(delegate.encode(src), DEFAULT_CHARSET); } else { // JAXB fallback for String case return DatatypeConverter.printBase64Binary(src); } } /** * Base64-decode the given byte array from an UTF-8 String. * @param src the encoded UTF-8 String (may be {@code null}) * @return the original byte array (or {@code null} if the input was {@code null}) */ public static byte[] decodeFromString(String src) { if (src == null) { return null; } if (src.length() == 0) { return new byte[0]; } if (delegate != null) { // Full encoder available return delegate.decode(src.getBytes(DEFAULT_CHARSET)); } else { // JAXB fallback for String case return DatatypeConverter.parseBase64Binary(src); } } interface Base64Delegate { byte[] encode(byte[] src); byte[] decode(byte[] src); } @UsesJava8 static class JdkBase64Delegate implements Base64Delegate { public byte[] encode(byte[] src) { if (src == null || src.length == 0) { return src; } return Base64.getEncoder().encode(src); } public byte[] decode(byte[] src) { if (src == null || src.length == 0) { return src; } return Base64.getDecoder().decode(src); } } static class CommonsCodecBase64Delegate implements Base64Delegate { private final org.apache.commons.codec.binary.Base64 base64 = new org.apache.commons.codec.binary.Base64(); public byte[] encode(byte[] src) { return this.base64.encode(src); } public byte[] decode(byte[] src) { return this.base64.decode(src); } } }





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