base64u.java

java base64

package com.mindprod.base64;

/**
 * <pre>
 *        Freeware from:
 *        Roedy Green
 *        Canadian Mind Products
 *        #101 - 2536 Wark Street
 *        Victoria, BC Canada V8T 4G8
 *        tel:[phone]
 *        roedy g at mindprod dotcom
 * <p/>
 *        Works exactly like Base64 except avoids using the characters
 *        + / and =.  This means Base64u-encoded data can be used either
 * URLCoded or plain in
 *        URL-Encoded contexts such as GET, PUT or URLs. You can treat the
 * output either as
 *        not needing encoding or already URLEncoded.
 * </pre>
 *
 * @noinspection WeakerAccess
 */
public final class Base64u extends Base64
    {
    // ------------------------------ FIELDS ------------------------------

    /**
     * letter of the alphabet used to encode binary values 0..63.
     */
    private static char[] vc;

    /**
     * binary value encoded by a given letter of the alphabet 0..63.
     */
    private static int[] cv;

    // -------------------------- PUBLIC INSTANCE  METHODS --------------------------
    /**
     * constructor.
     *
     * @noinspection WeakerAccess
     */
    public Base64u()
        {
        spec1 = '-';
        spec2 = '_';
        spec3 = '*';

        initTables();
        }

    // -------------------------- OTHER METHODS --------------------------

    /**
     * Initialise both static and instance table.
     */
    private void initTables()
        {
        /* initialise valueToChar and charToValue tables */

        if ( vc == null )
            {
            // statics are not initialised yet

            vc = new char[64];

            cv = new int[256];

            // build translate valueToChar table only once.
            // 0..25 -> 'A'..'Z'
            for ( int i = 0; i <= 25; i++ )
                {
                vc[ i ] = ( char ) ( 'A' + i );
                }
            // 26..51 -> 'a'..'z'
            for ( int i = 0; i <= 25; i++ )
                {
                vc[ i + 26 ] = ( char ) ( 'a' + i );
                }
            // 52..61 -> '0'..'9'
            for ( int i = 0; i <= 9; i++ )
                {
                vc[ i + 52 ] = ( char ) ( '0' + i );
                }
            vc[ 62 ] = spec1;
            vc[ 63 ] = spec2;

            // build translate charToValue table only once.
            for ( int i = 0; i < 256; i++ )
                {
                cv[ i ] = IGNORE;// default is to ignore
                }

            for ( int i = 0; i < 64; i++ )
                {
                cv[ vc[ i ] ] = i;
                }

            cv[ spec3 ] = PAD;
            }
        valueToChar = vc;
        charToValue = cv;
        }

    // --------------------------- main() method ---------------------------

    /**
     * test driver.
     *
     * @param args not used .
     * @noinspection ConstantConditions
     */
    public static void main( String[] args )
        {
        if ( DEBUGGING )
            {
            byte[] a = { ( byte ) 0xfc, ( byte ) 0x0f, ( byte ) 0xc0 };
            byte[] b = { ( byte ) 0x03, ( byte ) 0xf0, ( byte ) 0x3f };
            byte[] c = { ( byte ) 0x00, ( byte ) 0x00, ( byte ) 0x00 };
            byte[] d = { ( byte ) 0xff, ( byte ) 0xff, ( byte ) 0xff };
            byte[] e = { ( byte ) 0xfc, ( byte ) 0x0f, ( byte ) 0xc0, ( byte ) 1 };
            byte[] f =
                    { ( byte ) 0xfc, ( byte ) 0x0f, ( byte ) 0xc0, ( byte ) 1, ( byte ) 2 };
            byte[] g = {
                    ( byte ) 0xfc,
                    ( byte ) 0x0f,
                    ( byte ) 0xc0,
                    ( byte ) 1,
                    ( byte ) 2,
                    ( byte ) 3 };
            byte[] h = "AAAAAAAAAAB".getBytes();

            show( a );
            show( b );
            show( c );
            show( d );
            show( e );
            show( f );
            show( g );
            show( h );
            Base64u b64 = new Base64u();
            show( b64.decode( b64.encode( a ) ) );
            show( b64.decode( b64.encode( b ) ) );
            show( b64.decode( b64.encode( c ) ) );
            show( b64.decode( b64.encode( d ) ) );
            show( b64.decode( b64.encode( e ) ) );
            show( b64.decode( b64.encode( f ) ) );
            show( b64.decode( b64.encode( g ) ) );
            show( b64.decode( b64.encode( h ) ) );
            b64.setLineLength( 8 );
            show( ( b64.encode( h ) ).getBytes() );
            }
        }// end main
    }// end Base64