base64.java.svn-base

来自「开源项目openfire的完整源程序」· SVN-BASE 代码 · 共 1,237 行 · 第 1/4 页

package org.jivesoftware.spark.util;

import org.jivesoftware.spark.util.log.Log;

/**
 * Used to encrypt and decrypt bytes -- string using Base64 encoding and decoding.
 */
public class Base64 {

/* ********  P U B L I C   F I E L D S  ******** */


    /**
     * No options specified. Value is zero.
     */
    public final static int NO_OPTIONS = 0;

    /**
     * Specify encoding.
     */
    public final static int ENCODE = 1;


    /**
     * Specify decoding.
     */
    public final static int DECODE = 0;


    /**
     * Specify that data should be gzip-compressed.
     */
    public final static int GZIP = 2;


    /**
     * Don't break lines when encoding (violates strict Base64 specification)
     */
    public final static int DONT_BREAK_LINES = 8;

/* ********  P R I V A T E   F I E L D S  ******** */


    /**
     * Maximum line length (76) of Base64 output.
     */
    private final static int MAX_LINE_LENGTH = 76;


    /**
     * The equals sign (=) as a byte.
     */
    private final static byte EQUALS_SIGN = (byte)'=';


    /**
     * The new line character (\n) as a byte.
     */
    private final static byte NEW_LINE = (byte)'\n';


    /**
     * Preferred encoding.
     */
    private final static String PREFERRED_ENCODING = "UTF-8";


    /**
     * The 64 valid Base64 values.
     */
    private final static byte[] ALPHABET;
    private final static byte[] _NATIVE_ALPHABET = /* May be something funny like EBCDIC */
            {
                    (byte)'A', (byte)'B', (byte)'C', (byte)'D', (byte)'E', (byte)'F', (byte)'G',
                    (byte)'H', (byte)'I', (byte)'J', (byte)'K', (byte)'L', (byte)'M', (byte)'N',
                    (byte)'O', (byte)'P', (byte)'Q', (byte)'R', (byte)'S', (byte)'T', (byte)'U',
                    (byte)'V', (byte)'W', (byte)'X', (byte)'Y', (byte)'Z',
                    (byte)'a', (byte)'b', (byte)'c', (byte)'d', (byte)'e', (byte)'f', (byte)'g',
                    (byte)'h', (byte)'i', (byte)'j', (byte)'k', (byte)'l', (byte)'m', (byte)'n',
                    (byte)'o', (byte)'p', (byte)'q', (byte)'r', (byte)'s', (byte)'t', (byte)'u',
                    (byte)'v', (byte)'w', (byte)'x', (byte)'y', (byte)'z',
                    (byte)'0', (byte)'1', (byte)'2', (byte)'3', (byte)'4', (byte)'5',
                    (byte)'6', (byte)'7', (byte)'8', (byte)'9', (byte)'+', (byte)'/'
            };

    /** Determine which ALPHABET to use. */
    static {
        byte[] __bytes;
        try {
            __bytes = new String("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/").getBytes(PREFERRED_ENCODING);
        }   // end try
        catch (java.io.UnsupportedEncodingException use) {
            __bytes = _NATIVE_ALPHABET; // Fall back to native encoding
        }   // end catch
        ALPHABET = __bytes;
    }   // end static


    /**
     * Translates a Base64 value to either its 6-bit reconstruction value
     * or a negative number indicating some other meaning.
     */
    private final static byte[] DECODABET =
            {
                    -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal  0 -  8
                    -5, -5, // Whitespace: Tab and Linefeed
                    -9, -9, // Decimal 11 - 12
                    -5, // Whitespace: Carriage Return
                    -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 14 - 26
                    -9, -9, -9, -9, -9, // Decimal 27 - 31
                    -5, // Whitespace: Space
                    -9, -9, -9, -9, -9, -9, -9, -9, -9, -9, // Decimal 33 - 42
                    62, // Plus sign at decimal 43
                    -9, -9, -9, // Decimal 44 - 46
                    63, // Slash at decimal 47
                    52, 53, 54, 55, 56, 57, 58, 59, 60, 61, // Numbers zero through nine
                    -9, -9, -9, // Decimal 58 - 60
                    -1, // Equals sign at decimal 61
                    -9, -9, -9, // Decimal 62 - 64
                    0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, // Letters 'A' through 'N'
                    14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, // Letters 'O' through 'Z'
                    -9, -9, -9, -9, -9, -9, // Decimal 91 - 96
                    26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, // Letters 'a' through 'm'
                    39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, // Letters 'n' through 'z'
                    -9, -9, -9, -9                                 // Decimal 123 - 126
                    /*,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,     // Decimal 127 - 139
      -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,     // Decimal 140 - 152
      -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,     // Decimal 153 - 165
      -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,     // Decimal 166 - 178
      -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,     // Decimal 179 - 191
      -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,     // Decimal 192 - 204
      -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,     // Decimal 205 - 217
      -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,     // Decimal 218 - 230
      -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,     // Decimal 231 - 243
      -9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9         // Decimal 244 - 255 */
            };

    private final static byte BAD_ENCODING = -9; // Indicates error in encoding
    private final static byte WHITE_SPACE_ENC = -5; // Indicates white space in encoding
    private final static byte EQUALS_SIGN_ENC = -1; // Indicates equals sign in encoding


    /**
     * Defeats instantiation.
     */
    private Base64() {
    }

/* ********  E N C O D I N G   M E T H O D S  ******** */


    /**
     * Encodes the first three bytes of array <var>threeBytes</var>
     * and returns a four-byte array in Base64 notation.
     *
     * @param threeBytes the array to convert
     * @return four byte array in Base64 notation.
     * @since 1.3
     */
    private static byte[] encode3to4(byte[] threeBytes) {
        return encode3to4(threeBytes, 3);
    }   // end encodeToBytes


    /**
     * Encodes up to the first three bytes of array <var>threeBytes</var>
     * and returns a four-byte array in Base64 notation.
     * The actual number of significant bytes in your array is
     * given by <var>numSigBytes</var>.
     * The array <var>threeBytes</var> needs only be as big as
     * <var>numSigBytes</var>.
     *
     * @param threeBytes  the array to convert
     * @param numSigBytes the number of significant bytes in your array
     * @return four byte array in Base64 notation.
     * @since 1.3
     */
    private static byte[] encode3to4(byte[] threeBytes, int numSigBytes) {
        byte[] dest = new byte[4];
        encode3to4(threeBytes, 0, numSigBytes, dest, 0);
        return dest;
    }

    /**
     * Encodes up to the first three bytes of array <var>threeBytes</var>
     * and returns a four-byte array in Base64 notation.
     * The actual number of significant bytes in your array is
     * given by <var>numSigBytes</var>.
     * The array <var>threeBytes</var> needs only be as big as
     * <var>numSigBytes</var>.
     * Code can reuse a byte array by passing a four-byte array as <var>b4</var>.
     *
     * @param b4          A reusable byte array to reduce array instantiation
     * @param threeBytes  the array to convert
     * @param numSigBytes the number of significant bytes in your array
     * @return four byte array in Base64 notation.
     * @since 1.5.1
     */
    private static byte[] encode3to4(byte[] b4, byte[] threeBytes, int numSigBytes) {
        encode3to4(threeBytes, 0, numSigBytes, b4, 0);
        return b4;
    }   // end encode3to4


    /**
     * Encodes up to three bytes of the array <var>source</var>
     * and writes the resulting four Base64 bytes to <var>destination</var>.
     * The source and destination arrays can be manipulated
     * anywhere along their length by specifying
     * <var>srcOffset</var> and <var>destOffset</var>.
     * This method does not check to make sure your arrays
     * are large enough to accomodate <var>srcOffset</var> + 3 for
     * the <var>source</var> array or <var>destOffset</var> + 4 for
     * the <var>destination</var> array.
     * The actual number of significant bytes in your array is
     * given by <var>numSigBytes</var>.
     *
     * @param source      the array to convert
     * @param srcOffset   the index where conversion begins
     * @param numSigBytes the number of significant bytes in your array
     * @param destination the array to hold the conversion
     * @param destOffset  the index where output will be put
     * @return the <var>destination</var> array
     * @since 1.3
     */
    private static byte[] encode3to4(byte[] source, int srcOffset, int numSigBytes,
                                     byte[] destination, int destOffset) {
        //           1         2         3
        // 01234567890123456789012345678901 Bit position
        // --------000000001111111122222222 Array position from threeBytes
        // --------|    ||    ||    ||    | Six bit groups to index ALPHABET
        //          >>18  >>12  >> 6  >> 0  Right shift necessary
        //                0x3f  0x3f  0x3f  Additional AND

        // Create buffer with zero-padding if there are only one or two
        // significant bytes passed in the array.
        // We have to shift left 24 in order to flush out the 1's that appear
        // when Java treats a value as negative that is cast from a byte to an int.
        int inBuff = (numSigBytes > 0 ? ((source[srcOffset] << 24) >>> 8) : 0)
                | (numSigBytes > 1 ? ((source[srcOffset + 1] << 24) >>> 16) : 0)
                | (numSigBytes > 2 ? ((source[srcOffset + 2] << 24) >>> 24) : 0);

        switch (numSigBytes) {
            case 3:
                destination[destOffset] = ALPHABET[(inBuff >>> 18)];
                destination[destOffset + 1] = ALPHABET[(inBuff >>> 12) & 0x3f];
                destination[destOffset + 2] = ALPHABET[(inBuff >>> 6) & 0x3f];
                destination[destOffset + 3] = ALPHABET[(inBuff) & 0x3f];
                return destination;

            case 2:
                destination[destOffset] = ALPHABET[(inBuff >>> 18)];
                destination[destOffset + 1] = ALPHABET[(inBuff >>> 12) & 0x3f];
                destination[destOffset + 2] = ALPHABET[(inBuff >>> 6) & 0x3f];
                destination[destOffset + 3] = EQUALS_SIGN;
                return destination;

            case 1:
                destination[destOffset] = ALPHABET[(inBuff >>> 18)];
                destination[destOffset + 1] = ALPHABET[(inBuff >>> 12) & 0x3f];
                destination[destOffset + 2] = EQUALS_SIGN;
                destination[destOffset + 3] = EQUALS_SIGN;
                return destination;

            default:
                return destination;
        }   // end switch
    }   // end encode3to4


    /**
     * Serializes an object and returns the Base64-encoded
     * version of that serialized object. If the object
     * cannot be serialized or there is another error,
     * the method will return <tt>null</tt>.
     * The object is not GZip-compressed before being encoded.
     *
     * @param serializableObject The object to encode
     * @return The Base64-encoded object
     * @since 1.4
     */
    public static String encodeObject(java.io.Serializable serializableObject) {
        return encodeObject(serializableObject, NO_OPTIONS);
    }   // end encodeObject


    /**
     * Serializes an object and returns the Base64-encoded
     * version of that serialized object. If the object
     * cannot be serialized or there is another error,
     * the method will return <tt>null</tt>.
     * <p/>
     * Valid options:<pre>
     *   GZIP: gzip-compresses object before encoding it.
     *   DONT_BREAK_LINES: don't break lines at 76 characters
     *     <i>Note: Technically, this makes your encoding non-compliant.</i>
     * </pre>
     * <p/>
     * Example: <code>encodeObject( myObj, Base64.GZIP )</code> or
     * <p/>
     * Example: <code>encodeObject( myObj, Base64.GZIP | Base64.DONT_BREAK_LINES )</code>
     *
     * @param serializableObject The object to encode
     * @return The Base64-encoded object
     * @see Base64#GZIP
     * @see Base64#DONT_BREAK_LINES
     * @since 2.0
     */
    public static String encodeObject(java.io.Serializable serializableObject, int options) {
        // Streams