/*
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* Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
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* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*/
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// Base64解码 使用1.8版本源码 鉴于1.8部分特性1.6版本使用不到 故只保留能使用到的代码 其余删除
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package com.iailab.netsdk.common;
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import java.nio.ByteBuffer;
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import java.nio.charset.Charset;
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import java.util.Arrays;
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/**
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* This class consists exclusively of static methods for obtaining
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* encoders and decoders for the Base64 encoding scheme. The
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* implementation of this class supports the following types of Base64
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* as specified in
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* <a href="http://www.ietf.org/rfc/rfc4648.txt">RFC 4648</a> and
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*
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* <ul>
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* <li><a name="basic"><b>Basic</b></a>
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* <p> Uses "The Base64 Alphabet" as specified in Table 1 of
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* RFC 4648 and RFC 2045 for encoding and decoding operation.
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* The encoder does not add any line feed (line separator)
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* character. The decoder rejects data that contains characters
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* outside the base64 alphabet.</p></li>
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*
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* <p> Unless otherwise noted, passing a {@code null} argument to a
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* method of this class will cause a {@link NullPointerException
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* NullPointerException} to be thrown.
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*
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* @author Xueming Shen
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* @since 1.8
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*/
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public class Base64 {
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private Base64() {}
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/**
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* Returns a {@link Encoder} that encodes using the
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* <a href="#basic">Basic</a> type base64 encoding scheme.
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*
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* @return A Base64 encoder.
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*/
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public static Encoder getEncoder() {
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return Encoder.RFC4648;
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}
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/**
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* This class implements an encoder for encoding byte data using
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* the Base64 encoding scheme as specified in RFC 4648 and RFC 2045.
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*
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* <p> Instances of {@link Encoder} class are safe for use by
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* multiple concurrent threads.
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*
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* <p> Unless otherwise noted, passing a {@code null} argument to
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* a method of this class will cause a
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* {@link NullPointerException NullPointerException} to
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* be thrown.
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*
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* @see Decoder
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* @since 1.8
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*/
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public static class Encoder {
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private final byte[] newline;
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private final int linemax;
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private final boolean isURL;
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private final boolean doPadding;
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private Encoder(boolean isURL, byte[] newline, int linemax, boolean doPadding) {
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this.isURL = isURL;
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this.newline = newline;
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this.linemax = linemax;
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this.doPadding = doPadding;
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}
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/**
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* This array is a lookup table that translates 6-bit positive integer
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* index values into their "Base64 Alphabet" equivalents as specified
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* in "Table 1: The Base64 Alphabet" of RFC 2045 (and RFC 4648).
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*/
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private static final char[] toBase64 = {
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'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
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'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
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'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
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'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
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'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/'
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};
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/**
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* It's the lookup table for "URL and Filename safe Base64" as specified
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* in Table 2 of the RFC 4648, with the '+' and '/' changed to '-' and
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* '_'. This table is used when BASE64_URL is specified.
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*/
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private static final char[] toBase64URL = {
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'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
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'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
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'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
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'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
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'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '-', '_'
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};
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static final Encoder RFC4648 = new Encoder(false, null, -1, true);
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private final int outLength(int srclen) {
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int len = 0;
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if (doPadding) {
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len = 4 * ((srclen + 2) / 3);
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} else {
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int n = srclen % 3;
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len = 4 * (srclen / 3) + (n == 0 ? 0 : n + 1);
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}
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if (linemax > 0) // line separators
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len += (len - 1) / linemax * newline.length;
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return len;
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}
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/**
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* Encodes all bytes from the specified byte array into a newly-allocated
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* byte array using the {@link Base64} encoding scheme. The returned byte
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* array is of the length of the resulting bytes.
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*
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* @param src
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* the byte array to encode
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* @return A newly-allocated byte array containing the resulting
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* encoded bytes.
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*/
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public byte[] encode(byte[] src) {
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int len = outLength(src.length); // dst array size
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byte[] dst = new byte[len];
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int ret = encode0(src, 0, src.length, dst);
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if (ret != dst.length)
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return Arrays.copyOf(dst, ret);
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return dst;
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}
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/**
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* Encodes all bytes from the specified byte array using the
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* {@link Base64} encoding scheme, writing the resulting bytes to the
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* given output byte array, starting at offset 0.
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*
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* <p> It is the responsibility of the invoker of this method to make
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* sure the output byte array {@code dst} has enough space for encoding
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* all bytes from the input byte array. No bytes will be written to the
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* output byte array if the output byte array is not big enough.
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*
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* @param src
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* the byte array to encode
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* @param dst
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* the output byte array
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* @return The number of bytes written to the output byte array
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*
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* @throws IllegalArgumentException if {@code dst} does not have enough
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* space for encoding all input bytes.
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*/
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public int encode(byte[] src, byte[] dst) {
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int len = outLength(src.length); // dst array size
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if (dst.length < len)
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throw new IllegalArgumentException(
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"Output byte array is too small for encoding all input bytes");
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return encode0(src, 0, src.length, dst);
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}
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/**
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* Encodes the specified byte array into a String using the {@link Base64}
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* encoding scheme.
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*
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* <p> In other words, an invocation of this method has exactly the same
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* effect as invoking
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* {@code new String(encode(src), StandardCharsets.ISO_8859_1)}.
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*
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* @param src
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* the byte array to encode
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* @return A String containing the resulting Base64 encoded characters
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*/
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@SuppressWarnings("deprecation")
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public String encodeToString(byte[] src) {
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byte[] encoded = encode(src);
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return new String(encoded, 0, 0, encoded.length);
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}
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/**
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* Returns an encoder instance that encodes equivalently to this one,
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* but without adding any padding character at the end of the encoded
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* byte data.
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*
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* <p> The encoding scheme of this encoder instance is unaffected by
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* this invocation. The returned encoder instance should be used for
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* non-padding encoding operation.
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*
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* @return an equivalent encoder that encodes without adding any
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* padding character at the end
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*/
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public Encoder withoutPadding() {
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if (!doPadding)
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return this;
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return new Encoder(isURL, newline, linemax, false);
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}
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private int encode0(byte[] src, int off, int end, byte[] dst) {
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char[] base64 = isURL ? toBase64URL : toBase64;
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int sp = off;
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int slen = (end - off) / 3 * 3;
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int sl = off + slen;
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if (linemax > 0 && slen > linemax / 4 * 3)
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slen = linemax / 4 * 3;
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int dp = 0;
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while (sp < sl) {
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int sl0 = Math.min(sp + slen, sl);
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for (int sp0 = sp, dp0 = dp ; sp0 < sl0; ) {
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int bits = (src[sp0++] & 0xff) << 16 |
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(src[sp0++] & 0xff) << 8 |
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(src[sp0++] & 0xff);
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dst[dp0++] = (byte)base64[(bits >>> 18) & 0x3f];
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dst[dp0++] = (byte)base64[(bits >>> 12) & 0x3f];
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dst[dp0++] = (byte)base64[(bits >>> 6) & 0x3f];
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dst[dp0++] = (byte)base64[bits & 0x3f];
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}
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int dlen = (sl0 - sp) / 3 * 4;
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dp += dlen;
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sp = sl0;
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if (dlen == linemax && sp < end) {
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for (byte b : newline){
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dst[dp++] = b;
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}
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}
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}
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if (sp < end) { // 1 or 2 leftover bytes
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int b0 = src[sp++] & 0xff;
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dst[dp++] = (byte)base64[b0 >> 2];
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if (sp == end) {
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dst[dp++] = (byte)base64[(b0 << 4) & 0x3f];
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if (doPadding) {
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dst[dp++] = '=';
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dst[dp++] = '=';
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}
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} else {
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int b1 = src[sp++] & 0xff;
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dst[dp++] = (byte)base64[(b0 << 4) & 0x3f | (b1 >> 4)];
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dst[dp++] = (byte)base64[(b1 << 2) & 0x3f];
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if (doPadding) {
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dst[dp++] = '=';
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}
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}
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}
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return dp;
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}
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}
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/**
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* Returns a {@link Decoder} that decodes using the
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* <a href="#basic">Basic</a> type base64 encoding scheme.
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*
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* @return A Base64 decoder.
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*/
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public static Decoder getDecoder() {
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return Decoder.RFC4648;
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}
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/**
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* This class implements a decoder for decoding byte data using the
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* Base64 encoding scheme as specified in RFC 4648 and RFC 2045.
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*
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* <p> The Base64 padding character {@code '='} is accepted and
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* interpreted as the end of the encoded byte data, but is not
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* required. So if the final unit of the encoded byte data only has
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* two or three Base64 characters (without the corresponding padding
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* character(s) padded), they are decoded as if followed by padding
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* character(s). If there is a padding character present in the
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* final unit, the correct number of padding character(s) must be
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* present, otherwise {@code IllegalArgumentException} (
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* {@code IOException} when reading from a Base64 stream) is thrown
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* during decoding.
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*
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* <p> Instances of {@link Decoder} class are safe for use by
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* multiple concurrent threads.
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*
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* <p> Unless otherwise noted, passing a {@code null} argument to
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* a method of this class will cause a
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* {@link NullPointerException NullPointerException} to
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* be thrown.
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*
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* @see Encoder
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* @since 1.8
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*/
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public static class Decoder {
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private final boolean isURL;
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private final boolean isMIME;
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private Decoder(boolean isURL, boolean isMIME) {
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this.isURL = isURL;
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this.isMIME = isMIME;
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}
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/**
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* Lookup table for decoding unicode characters drawn from the
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* "Base64 Alphabet" (as specified in Table 1 of RFC 2045) into
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* their 6-bit positive integer equivalents. Characters that
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* are not in the Base64 alphabet but fall within the bounds of
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* the array are encoded to -1.
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*
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*/
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private static final int[] fromBase64 = new int[256];
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static {
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Arrays.fill(fromBase64, -1);
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for (int i = 0; i < Encoder.toBase64.length; i++)
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fromBase64[Encoder.toBase64[i]] = i;
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fromBase64['='] = -2;
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}
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/**
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* Lookup table for decoding "URL and Filename safe Base64 Alphabet"
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* as specified in Table2 of the RFC 4648.
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*/
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private static final int[] fromBase64URL = new int[256];
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static {
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Arrays.fill(fromBase64URL, -1);
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for (int i = 0; i < Encoder.toBase64URL.length; i++)
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fromBase64URL[Encoder.toBase64URL[i]] = i;
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fromBase64URL['='] = -2;
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}
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static final Decoder RFC4648 = new Decoder(false, false);
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static final Decoder RFC4648_URLSAFE = new Decoder(true, false);
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static final Decoder RFC2045 = new Decoder(false, true);
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/**
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* Decodes all bytes from the input byte array using the {@link Base64}
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* encoding scheme, writing the results into a newly-allocated output
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* byte array. The returned byte array is of the length of the resulting
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* bytes.
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*
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* @param src
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* the byte array to decode
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*
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* @return A newly-allocated byte array containing the decoded bytes.
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*
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* @throws IllegalArgumentException
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* if {@code src} is not in valid Base64 scheme
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*/
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public byte[] decode(byte[] src) {
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byte[] dst = new byte[outLength(src, 0, src.length)];
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int ret = decode0(src, 0, src.length, dst);
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if (ret != dst.length) {
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dst = Arrays.copyOf(dst, ret);
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}
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return dst;
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}
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public byte[] decode(String src) {
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return decode(src.getBytes(Charset.forName("ISO-8859-1")));
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}
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/**
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* Decodes all bytes from the input byte array using the {@link Base64}
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* encoding scheme, writing the results into the given output byte array,
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* starting at offset 0.
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*
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* <p> It is the responsibility of the invoker of this method to make
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* sure the output byte array {@code dst} has enough space for decoding
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* all bytes from the input byte array. No bytes will be be written to
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* the output byte array if the output byte array is not big enough.
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*
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* <p> If the input byte array is not in valid Base64 encoding scheme
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* then some bytes may have been written to the output byte array before
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* IllegalargumentException is thrown.
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*
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* @param src
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* the byte array to decode
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* @param dst
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* the output byte array
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*
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* @return The number of bytes written to the output byte array
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*
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* @throws IllegalArgumentException
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* if {@code src} is not in valid Base64 scheme, or {@code dst}
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* does not have enough space for decoding all input bytes.
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*/
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public int decode(byte[] src, byte[] dst) {
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int len = outLength(src, 0, src.length);
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if (dst.length < len)
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throw new IllegalArgumentException(
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"Output byte array is too small for decoding all input bytes");
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return decode0(src, 0, src.length, dst);
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}
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/**
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* Decodes all bytes from the input byte buffer using the {@link Base64}
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* encoding scheme, writing the results into a newly-allocated ByteBuffer.
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*
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* <p> Upon return, the source buffer's position will be updated to
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* its limit; its limit will not have been changed. The returned
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* output buffer's position will be zero and its limit will be the
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* number of resulting decoded bytes
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*
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* <p> {@code IllegalArgumentException} is thrown if the input buffer
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* is not in valid Base64 encoding scheme. The position of the input
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* buffer will not be advanced in this case.
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*
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* @param buffer
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* the ByteBuffer to decode
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*
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* @return A newly-allocated byte buffer containing the decoded bytes
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*
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* @throws IllegalArgumentException
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* if {@code src} is not in valid Base64 scheme.
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*/
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public ByteBuffer decode(ByteBuffer buffer) {
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int pos0 = buffer.position();
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try {
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byte[] src;
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int sp, sl;
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if (buffer.hasArray()) {
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src = buffer.array();
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sp = buffer.arrayOffset() + buffer.position();
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sl = buffer.arrayOffset() + buffer.limit();
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buffer.position(buffer.limit());
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} else {
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src = new byte[buffer.remaining()];
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buffer.get(src);
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sp = 0;
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sl = src.length;
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}
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byte[] dst = new byte[outLength(src, sp, sl)];
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return ByteBuffer.wrap(dst, 0, decode0(src, sp, sl, dst));
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} catch (IllegalArgumentException iae) {
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buffer.position(pos0);
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throw iae;
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}
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}
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private int outLength(byte[] src, int sp, int sl) {
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int[] base64 = isURL ? fromBase64URL : fromBase64;
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int paddings = 0;
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int len = sl - sp;
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if (len == 0)
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return 0;
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if (len < 2) {
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if (isMIME && base64[0] == -1)
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return 0;
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throw new IllegalArgumentException(
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"Input byte[] should at least have 2 bytes for base64 bytes");
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}
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if (isMIME) {
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// scan all bytes to fill out all non-alphabet. a performance
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// trade-off of pre-scan or Arrays.copyOf
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int n = 0;
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while (sp < sl) {
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int b = src[sp++] & 0xff;
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if (b == '=') {
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len -= (sl - sp + 1);
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break;
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}
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if ((b = base64[b]) == -1)
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n++;
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}
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len -= n;
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} else {
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if (src[sl - 1] == '=') {
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paddings++;
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if (src[sl - 2] == '=')
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paddings++;
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}
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}
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if (paddings == 0 && (len & 0x3) != 0)
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paddings = 4 - (len & 0x3);
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return 3 * ((len + 3) / 4) - paddings;
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}
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private int decode0(byte[] src, int sp, int sl, byte[] dst) {
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int[] base64 = isURL ? fromBase64URL : fromBase64;
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int dp = 0;
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int bits = 0;
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int shiftto = 18; // pos of first byte of 4-byte atom
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while (sp < sl) {
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int b = src[sp++] & 0xff;
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if ((b = base64[b]) < 0) {
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if (b == -2) { // padding byte '='
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// = shiftto==18 unnecessary padding
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// x= shiftto==12 a dangling single x
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// x to be handled together with non-padding case
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// xx= shiftto==6&&sp==sl missing last =
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// xx=y shiftto==6 last is not =
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if (shiftto == 6 && (sp == sl || src[sp++] != '=') ||
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shiftto == 18) {
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throw new IllegalArgumentException(
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"Input byte array has wrong 4-byte ending unit");
|
}
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break;
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}
|
if (isMIME) // skip if for rfc2045
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continue;
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else
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throw new IllegalArgumentException(
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"Illegal base64 character " +
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Integer.toString(src[sp - 1], 16));
|
}
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bits |= (b << shiftto);
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shiftto -= 6;
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if (shiftto < 0) {
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dst[dp++] = (byte)(bits >> 16);
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dst[dp++] = (byte)(bits >> 8);
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dst[dp++] = (byte)(bits);
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shiftto = 18;
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bits = 0;
|
}
|
}
|
// reached end of byte array or hit padding '=' characters.
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if (shiftto == 6) {
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dst[dp++] = (byte)(bits >> 16);
|
} else if (shiftto == 0) {
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dst[dp++] = (byte)(bits >> 16);
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dst[dp++] = (byte)(bits >> 8);
|
} else if (shiftto == 12) {
|
// dangling single "x", incorrectly encoded.
|
throw new IllegalArgumentException(
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"Last unit does not have enough valid bits");
|
}
|
// anything left is invalid, if is not MIME.
|
// if MIME, ignore all non-base64 character
|
while (sp < sl) {
|
if (isMIME && base64[src[sp++]] < 0)
|
continue;
|
throw new IllegalArgumentException(
|
"Input byte array has incorrect ending byte at " + sp);
|
}
|
return dp;
|
}
|
}
|
}
|
