org.springframework.util.Base64Utils Maven / Gradle / Ivy
/*
* Copyright 2002-2017 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
*
* 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.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.
* However, this does not apply when using the "UrlSafe" methods for RFC 4648 "URL and
* Filename Safe Alphabet"; a delegate is required.
*
*
Note: Apache Commons Codec does not add padding ({@code =}) when encoding
* with the URL and Filename Safe Alphabet.
*
* @author Juergen Hoeller
* @author Gary Russell
* @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 using the RFC 4648
* "URL and Filename Safe Alphabet".
* @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
* @since 4.2.4
*/
public static byte[] encodeUrlSafe(byte[] src) {
assertDelegateAvailable();
return delegate.encodeUrlSafe(src);
}
/**
* Base64-decode the given byte array using the RFC 4648
* "URL and Filename Safe Alphabet".
* @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
* @since 4.2.4
*/
public static byte[] decodeUrlSafe(byte[] src) {
assertDelegateAvailable();
return delegate.decodeUrlSafe(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.isEmpty()) {
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);
}
}
/**
* Base64-encode the given byte array to a String using the RFC 4648
* "URL and Filename Safe Alphabet".
* @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})
* @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 String encodeToUrlSafeString(byte[] src) {
assertDelegateAvailable();
return new String(delegate.encodeUrlSafe(src), DEFAULT_CHARSET);
}
/**
* Base64-decode the given byte array from an UTF-8 String using the RFC 4648
* "URL and Filename Safe Alphabet".
* @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})
* @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[] decodeFromUrlSafeString(String src) {
assertDelegateAvailable();
return delegate.decodeUrlSafe(src.getBytes(DEFAULT_CHARSET));
}
interface Base64Delegate {
byte[] encode(byte[] src);
byte[] decode(byte[] src);
byte[] encodeUrlSafe(byte[] src);
byte[] decodeUrlSafe(byte[] src);
}
@UsesJava8
static class JdkBase64Delegate implements Base64Delegate {
@Override
public byte[] encode(byte[] src) {
if (src == null || src.length == 0) {
return src;
}
return Base64.getEncoder().encode(src);
}
@Override
public byte[] decode(byte[] src) {
if (src == null || src.length == 0) {
return src;
}
return Base64.getDecoder().decode(src);
}
@Override
public byte[] encodeUrlSafe(byte[] src) {
if (src == null || src.length == 0) {
return src;
}
return Base64.getUrlEncoder().encode(src);
}
@Override
public byte[] decodeUrlSafe(byte[] src) {
if (src == null || src.length == 0) {
return src;
}
return Base64.getUrlDecoder().decode(src);
}
}
static class CommonsCodecBase64Delegate implements Base64Delegate {
private final org.apache.commons.codec.binary.Base64 base64 =
new org.apache.commons.codec.binary.Base64();
private final org.apache.commons.codec.binary.Base64 base64UrlSafe =
new org.apache.commons.codec.binary.Base64(0, null, true);
@Override
public byte[] encode(byte[] src) {
return this.base64.encode(src);
}
@Override
public byte[] decode(byte[] src) {
return this.base64.decode(src);
}
@Override
public byte[] encodeUrlSafe(byte[] src) {
return this.base64UrlSafe.encode(src);
}
@Override
public byte[] decodeUrlSafe(byte[] src) {
return this.base64UrlSafe.decode(src);
}
}
}