Android Open Source - kakao-android-sdk-standalone Base64

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The source code is released under:
Apache License
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Java Source Code

/*
 * This class is a part of Base64 in Apach commons codec.
 */*  ww  w. ja va2  s . com*/
 * 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 com.kakao.helper;

import java.io.UnsupportedEncodingException;
import java.nio.charset.Charset;
import java.util.Arrays;

/**
 *
 * @author MJ
 */
public class Base64 {
    private static final int BYTES_PER_UNENCODED_BLOCK = 3;
    private static final int BYTES_PER_ENCODED_BLOCK = 4;
    private static final int DEFAULT_BUFFER_RESIZE_FACTOR = 2;
    private static final int DEFAULT_BUFFER_SIZE = 8192;
    private static final int MASK_6BITS = 0x3f;
    private static final int EOF = -1;
    private static final int MIME_CHUNK_SIZE = 76;
    private static final byte[] CHUNK_SEPARATOR = {'\r', '\n'};
    private static final Charset UTF_8 = Charset.forName("UTF-8");

    private final int unencodedBlockSize;
    private final int encodedBlockSize;
    private final int lineLength;
    private final int chunkSeparatorLength;
    private static final byte PAD_DEFAULT = '=';
    private final byte PAD = PAD_DEFAULT;

    private final byte[] lineSeparator;
    @SuppressWarnings("unused")
    private final int decodeSize;
    private final int encodeSize;
    private final byte[] encodeTable;
    private final byte[] decodeTable = DECODE_TABLE;

    private static final byte[] DECODE_TABLE = {
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, 62, -1, 63, 52, 53, 54,
        55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4,
        5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,
        24, 25, -1, -1, -1, -1, 63, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34,
        35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51
    };

    private static final byte[] STANDARD_ENCODE_TABLE = {
        'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
        'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
        'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
        'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
        '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/'
    };

    private static final byte[] URL_SAFE_ENCODE_TABLE = {
        'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
        'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
        'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
        'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
        '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '-', '_'
    };

    static class Context {
        int ibitWorkArea;
        long lbitWorkArea;
        byte[] buffer;
        int pos;
        int readPos;
        boolean eof;
        int currentLinePos;
        int modulus;

        Context() {
        }

        public String toString() {
            return String.format("%s[buffer=%s, currentLinePos=%s, eof=%s, ibitWorkArea=%s, lbitWorkArea=%s, " +
                "modulus=%s, pos=%s, readPos=%s]", this.getClass().getSimpleName(), Arrays.toString(buffer),
                currentLinePos, eof, ibitWorkArea, lbitWorkArea, modulus, pos, readPos);
        }
    }


    private Base64(final boolean urlSafe) {
        this(MIME_CHUNK_SIZE, CHUNK_SEPARATOR, urlSafe);
    }

    private Base64(final int lineLength, final byte[] lineSeparator, final boolean urlSafe) {
        this.unencodedBlockSize = BYTES_PER_UNENCODED_BLOCK;
        this.encodedBlockSize = BYTES_PER_ENCODED_BLOCK;
        this.chunkSeparatorLength = lineSeparator == null ? 0 : lineSeparator.length;
        final boolean useChunking = lineLength > 0 && chunkSeparatorLength > 0;
        this.lineLength = useChunking ? (lineLength / encodedBlockSize) * encodedBlockSize : 0;

        if (lineSeparator != null) {
            if (containsAlphabetOrPad(lineSeparator)) {
                final String sep = newStringUtf8(lineSeparator);
                throw new IllegalArgumentException("lineSeparator must not contain base64 characters: [" + sep + "]");
            }
            if (lineLength > 0) {
                this.encodeSize = BYTES_PER_ENCODED_BLOCK + lineSeparator.length;
                this.lineSeparator = new byte[lineSeparator.length];
                System.arraycopy(lineSeparator, 0, this.lineSeparator, 0, lineSeparator.length);
            } else {
                this.encodeSize = BYTES_PER_ENCODED_BLOCK;
                this.lineSeparator = null;
            }
        } else {
            this.encodeSize = BYTES_PER_ENCODED_BLOCK;
            this.lineSeparator = null;
        }
        this.decodeSize = this.encodeSize - 1;
        this.encodeTable = urlSafe ? URL_SAFE_ENCODE_TABLE : STANDARD_ENCODE_TABLE;
    }

    boolean containsAlphabetOrPad(final byte[] arrayOctet) {
        if (arrayOctet == null) {
            return false;
        }
        for (final byte element : arrayOctet) {
            if (PAD == element || isInAlphabet(element)) {
                return true;
            }
        }
        return false;
    }

    public static String encodeBase64URLSafeString(final byte[] binaryData) {
        return newStringUtf8(encodeBase64(binaryData, false, true));
    }

    private static byte[] encodeBase64(final byte[] binaryData, final boolean isChunked, final boolean urlSafe) {
        return encodeBase64(binaryData, isChunked, urlSafe, Integer.MAX_VALUE);
    }

    private static byte[] encodeBase64(final byte[] binaryData, final boolean isChunked,
                                       final boolean urlSafe, final int maxResultSize) {
        if (binaryData == null || binaryData.length == 0) {
            return binaryData;
        }

        final Base64 b64 = isChunked ? new Base64(urlSafe) : new Base64(0, CHUNK_SEPARATOR, urlSafe);
        final long len = b64.getEncodedLength(binaryData);
        if (len > maxResultSize) {
            throw new IllegalArgumentException("Input array too big, the output array would be bigger (" +
                len +
                ") than the specified maximum size of " +
                maxResultSize);
        }

        return b64.encode(binaryData);
    }

    byte[] encode(final byte[] pArray) {
        if (pArray == null || pArray.length == 0) {
            return pArray;
        }
        final Context context = new Context();
        encode(pArray, 0, pArray.length, context);
        encode(pArray, 0, EOF, context);
        final byte[] buf = new byte[context.pos - context.readPos];
        readResults(buf, 0, buf.length, context);
        return buf;
    }

    void encode(final byte[] in, int inPos, final int inAvail, final Context context) {
        if (context.eof) {
            return;
        }
        // inAvail < 0 is how we're informed of EOF in the underlying data we're
        // encoding.
        if (inAvail < 0) {
            context.eof = true;
            if (0 == context.modulus && lineLength == 0) {
                return; // no leftovers to process and not using chunking
            }
            final byte[] buffer = ensureBufferSize(encodeSize, context);
            final int savedPos = context.pos;
            switch (context.modulus) { // 0-2
                case 0: // nothing to do here
                    break;
                case 1: // 8 bits = 6 + 2
                    // top 6 bits:
                    buffer[context.pos++] = encodeTable[(context.ibitWorkArea >> 2) & MASK_6BITS];
                    // remaining 2:
                    buffer[context.pos++] = encodeTable[(context.ibitWorkArea << 4) & MASK_6BITS];
                    // URL-SAFE skips the padding to further reduce size.
                    if (encodeTable == STANDARD_ENCODE_TABLE) {
                        buffer[context.pos++] = PAD;
                        buffer[context.pos++] = PAD;
                    }
                    break;

                case 2: // 16 bits = 6 + 6 + 4
                    buffer[context.pos++] = encodeTable[(context.ibitWorkArea >> 10) & MASK_6BITS];
                    buffer[context.pos++] = encodeTable[(context.ibitWorkArea >> 4) & MASK_6BITS];
                    buffer[context.pos++] = encodeTable[(context.ibitWorkArea << 2) & MASK_6BITS];
                    // URL-SAFE skips the padding to further reduce size.
                    if (encodeTable == STANDARD_ENCODE_TABLE) {
                        buffer[context.pos++] = PAD;
                    }
                    break;
                default:
                    throw new IllegalStateException("Impossible modulus " + context.modulus);
            }
            context.currentLinePos += context.pos - savedPos; // keep track of current line position
            // if currentPos == 0 we are at the start of a line, so don't add CRLF
            if (lineLength > 0 && context.currentLinePos > 0) {
                System.arraycopy(lineSeparator, 0, buffer, context.pos, lineSeparator.length);
                context.pos += lineSeparator.length;
            }
        } else {
            for (int i = 0; i < inAvail; i++) {
                final byte[] buffer = ensureBufferSize(encodeSize, context);
                context.modulus = (context.modulus + 1) % BYTES_PER_UNENCODED_BLOCK;
                int b = in[inPos++];
                if (b < 0) {
                    b += 256;
                }
                context.ibitWorkArea = (context.ibitWorkArea << 8) + b; //  BITS_PER_BYTE
                if (0 == context.modulus) { // 3 bytes = 24 bits = 4 * 6 bits to extract
                    buffer[context.pos++] = encodeTable[(context.ibitWorkArea >> 18) & MASK_6BITS];
                    buffer[context.pos++] = encodeTable[(context.ibitWorkArea >> 12) & MASK_6BITS];
                    buffer[context.pos++] = encodeTable[(context.ibitWorkArea >> 6) & MASK_6BITS];
                    buffer[context.pos++] = encodeTable[context.ibitWorkArea & MASK_6BITS];
                    context.currentLinePos += BYTES_PER_ENCODED_BLOCK;
                    if (lineLength > 0 && lineLength <= context.currentLinePos) {
                        System.arraycopy(lineSeparator, 0, buffer, context.pos, lineSeparator.length);
                        context.pos += lineSeparator.length;
                        context.currentLinePos = 0;
                    }
                }
            }
        }
    }

    byte[] ensureBufferSize(final int size, final Context context) {
        if ((context.buffer == null) || (context.buffer.length < context.pos + size)) {
            return resizeBuffer(context);
        }
        return context.buffer;
    }

    int readResults(final byte[] b, final int bPos, final int bAvail, final Context context) {
        if (context.buffer != null) {
            final int len = Math.min(available(context), bAvail);
            System.arraycopy(context.buffer, context.readPos, b, bPos, len);
            context.readPos += len;
            if (context.readPos >= context.pos) {
                context.buffer = null; // so hasData() will return false, and this method can return -1
            }
            return len;
        }
        return context.eof ? EOF : 0;
    }

    int available(final Context context) {  // package protected for access from I/O streams
        return context.buffer != null ? context.pos - context.readPos : 0;
    }

    private byte[] resizeBuffer(final Context context) {
        if (context.buffer == null) {
            context.buffer = new byte[getDefaultBufferSize()];
            context.pos = 0;
            context.readPos = 0;
        } else {
            final byte[] b = new byte[context.buffer.length * DEFAULT_BUFFER_RESIZE_FACTOR];
            System.arraycopy(context.buffer, 0, b, 0, context.buffer.length);
            context.buffer = b;
        }
        return context.buffer;
    }

    int getDefaultBufferSize() {
        return DEFAULT_BUFFER_SIZE;
    }


    long getEncodedLength(final byte[] pArray) {
        long len = ((pArray.length + unencodedBlockSize - 1) / unencodedBlockSize) * (long) encodedBlockSize;
        if (lineLength > 0) {
            len += ((len + lineLength - 1) / lineLength) * chunkSeparatorLength;
        }
        return len;
    }

    private static String newStringUtf8(final byte[] bytes) {
        return newString(bytes, UTF_8);
    }

    private static String newString(final byte[] bytes, final Charset charset) {
        try {
            return bytes == null ? null : new String(bytes, charset.name());
        } catch (UnsupportedEncodingException e) {
            return null;
        }
    }

    boolean isInAlphabet(final byte octet) {
        return octet >= 0 && octet < decodeTable.length && decodeTable[octet] != -1;
    }
}
Java Source Code List
