base64.java

处理PDF

     * @since 1.4
     */
    public static String encodeBytes( byte[] source, int off, int len ) {
        return encodeBytes( source, off, len, NO_OPTIONS );
    }   // end encodeBytes
    
    
    
    /**
     * Encodes a byte array into Base64 notation.
     * <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>encodeBytes( myData, Base64.GZIP )</code> or
     * <p>
     * Example: <code>encodeBytes( myData, Base64.GZIP | Base64.DONT_BREAK_LINES )</code>
     *
     *
     * @param source The data to convert
     * @param off Offset in array where conversion should begin
     * @param len Length of data to convert
     * @param options Specified options
     *                alphabet type is pulled from this (standard, url-safe, ordered)
     * @see Base64#GZIP
     * @see Base64#DONT_BREAK_LINES
     * @since 2.0
     */
    public static String encodeBytes( byte[] source, int off, int len, int options ) {
        // Isolate options
        int dontBreakLines = ( options & DONT_BREAK_LINES );
        int gzip           = ( options & GZIP   );
        
        // Compress?
        if( gzip == GZIP ) {
            java.io.ByteArrayOutputStream  baos  = null;
            java.util.zip.GZIPOutputStream gzos  = null;
            Base64.OutputStream            b64os = null;
            
            
            try {
                // GZip -> Base64 -> ByteArray
                baos = new java.io.ByteArrayOutputStream();
                b64os = new Base64.OutputStream( baos, ENCODE | options );
                gzos  = new java.util.zip.GZIPOutputStream( b64os );
                
                gzos.write( source, off, len );
                gzos.close();
            }   // end try
            catch( java.io.IOException e ) {
                e.printStackTrace();
                return null;
            }   // end catch
            finally {
                try{ gzos.close();  } catch( Exception e ){}
                try{ b64os.close(); } catch( Exception e ){}
                try{ baos.close();  } catch( Exception e ){}
            }   // end finally
            
            // Return value according to relevant encoding.
            try {
                return new String( baos.toByteArray(), PREFERRED_ENCODING );
            }   // end try
            catch (java.io.UnsupportedEncodingException uue) {
                return new String( baos.toByteArray() );
            }   // end catch
        }   // end if: compress
        
        // Else, don't compress. Better not to use streams at all then.
        else {
            // Convert option to boolean in way that code likes it.
            boolean breakLines = dontBreakLines == 0;
            
            int    len43   = len * 4 / 3;
            byte[] outBuff = new byte[   ( len43 )                      // Main 4:3
            + ( (len % 3) > 0 ? 4 : 0 )      // Account for padding
            + (breakLines ? ( len43 / MAX_LINE_LENGTH ) : 0) ]; // New lines
            int d = 0;
            int e = 0;
            int len2 = len - 2;
            int lineLength = 0;
            for( ; d < len2; d+=3, e+=4 ) {
                encode3to4( source, d+off, 3, outBuff, e, options );
                
                lineLength += 4;
                if( breakLines && lineLength == MAX_LINE_LENGTH ) {
                    outBuff[e+4] = NEW_LINE;
                    e++;
                    lineLength = 0;
                }   // end if: end of line
            }   // en dfor: each piece of array
            
            if( d < len ) {
                encode3to4( source, d+off, len - d, outBuff, e, options );
                e += 4;
            }   // end if: some padding needed
            
            
            // Return value according to relevant encoding.
            try {
                return new String( outBuff, 0, e, PREFERRED_ENCODING );
            }   // end try
            catch (java.io.UnsupportedEncodingException uue) {
                return new String( outBuff, 0, e );
            }   // end catch
            
        }   // end else: don't compress
        
    }   // end encodeBytes
    
    
    
    
    
    /* ********  D E C O D I N G   M E T H O D S  ******** */
    
    
    /**
     * Decodes four bytes from array <var>source</var>
     * and writes the resulting bytes (up to three of them)
     * 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> + 4 for
     * the <var>source</var> array or <var>destOffset</var> + 3 for
     * the <var>destination</var> array.
     * This method returns the actual number of bytes that
     * were converted from the Base64 encoding.
     * <p>This is the lowest level of the decoding methods with
     * all possible parameters.</p>
     *
     *
     * @param source the array to convert
     * @param srcOffset the index where conversion begins
     * @param destination the array to hold the conversion
     * @param destOffset the index where output will be put
     * @param options alphabet type is pulled from this (standard, url-safe, ordered)
     * @return the number of decoded bytes converted
     * @since 1.3
     */
    private static int decode4to3( byte[] source, int srcOffset, byte[] destination, int destOffset, int options ) {
        byte[] DECODABET = getDecodabet( options );
        
        // Example: Dk==
        if( source[ srcOffset + 2] == EQUALS_SIGN ) {
            // Two ways to do the same thing. Don't know which way I like best.
            //int outBuff =   ( ( DECODABET[ source[ srcOffset    ] ] << 24 ) >>>  6 )
            //              | ( ( DECODABET[ source[ srcOffset + 1] ] << 24 ) >>> 12 );
            int outBuff =   ( ( DECODABET[ source[ srcOffset    ] ] & 0xFF ) << 18 )
            | ( ( DECODABET[ source[ srcOffset + 1] ] & 0xFF ) << 12 );
            
            destination[ destOffset ] = (byte)( outBuff >>> 16 );
            return 1;
        }
        
        // Example: DkL=
        else if( source[ srcOffset + 3 ] == EQUALS_SIGN ) {
            // Two ways to do the same thing. Don't know which way I like best.
            //int outBuff =   ( ( DECODABET[ source[ srcOffset     ] ] << 24 ) >>>  6 )
            //              | ( ( DECODABET[ source[ srcOffset + 1 ] ] << 24 ) >>> 12 )
            //              | ( ( DECODABET[ source[ srcOffset + 2 ] ] << 24 ) >>> 18 );
            int outBuff =   ( ( DECODABET[ source[ srcOffset     ] ] & 0xFF ) << 18 )
            | ( ( DECODABET[ source[ srcOffset + 1 ] ] & 0xFF ) << 12 )
            | ( ( DECODABET[ source[ srcOffset + 2 ] ] & 0xFF ) <<  6 );
            
            destination[ destOffset     ] = (byte)( outBuff >>> 16 );
            destination[ destOffset + 1 ] = (byte)( outBuff >>>  8 );
            return 2;
        }
        
        // Example: DkLE
        else {
            try{
                // Two ways to do the same thing. Don't know which way I like best.
                //int outBuff =   ( ( DECODABET[ source[ srcOffset     ] ] << 24 ) >>>  6 )
                //              | ( ( DECODABET[ source[ srcOffset + 1 ] ] << 24 ) >>> 12 )
                //              | ( ( DECODABET[ source[ srcOffset + 2 ] ] << 24 ) >>> 18 )
                //              | ( ( DECODABET[ source[ srcOffset + 3 ] ] << 24 ) >>> 24 );
                int outBuff =   ( ( DECODABET[ source[ srcOffset     ] ] & 0xFF ) << 18 )
                | ( ( DECODABET[ source[ srcOffset + 1 ] ] & 0xFF ) << 12 )
                | ( ( DECODABET[ source[ srcOffset + 2 ] ] & 0xFF ) <<  6)
                | ( ( DECODABET[ source[ srcOffset + 3 ] ] & 0xFF )      );
                
                
                destination[ destOffset     ] = (byte)( outBuff >> 16 );
                destination[ destOffset + 1 ] = (byte)( outBuff >>  8 );
                destination[ destOffset + 2 ] = (byte)( outBuff       );
                
                return 3;
            }catch( Exception e){
                System.out.println(""+source[srcOffset]+ ": " + ( DECODABET[ source[ srcOffset     ] ]  ) );
                System.out.println(""+source[srcOffset+1]+  ": " + ( DECODABET[ source[ srcOffset + 1 ] ]  ) );
                System.out.println(""+source[srcOffset+2]+  ": " + ( DECODABET[ source[ srcOffset + 2 ] ]  ) );
                System.out.println(""+source[srcOffset+3]+  ": " + ( DECODABET[ source[ srcOffset + 3 ] ]  ) );
                return -1;
            }   // end catch
        }
    }   // end decodeToBytes
    
    
    
    
    /**
     * Very low-level access to decoding ASCII characters in
     * the form of a byte array. Does not support automatically
     * gunzipping or any other "fancy" features.
     *
     * @param source The Base64 encoded data
     * @param off    The offset of where to begin decoding
     * @param len    The length of characters to decode
     * @return decoded data
     * @since 1.3
     */
    public static byte[] decode( byte[] source, int off, int len, int options ) {
        byte[] DECODABET = getDecodabet( options );
        
        int    len34   = len * 3 / 4;
        byte[] outBuff = new byte[ len34 ]; // Upper limit on size of output
        int    outBuffPosn = 0;
        
        byte[] b4        = new byte[4];
        int    b4Posn    = 0;
        int    i         = 0;
        byte   sbiCrop   = 0;
        byte   sbiDecode = 0;
        for( i = off; i < off+len; i++ ) {
            sbiCrop = (byte)(source[i] & 0x7f); // Only the low seven bits
            sbiDecode = DECODABET[ sbiCrop ];
            
            if( sbiDecode >= WHITE_SPACE_ENC ) // White space, Equals sign or better
            {
                if( sbiDecode >= EQUALS_SIGN_ENC ) {
                    b4[ b4Posn++ ] = sbiCrop;
                    if( b4Posn > 3 ) {
                        outBuffPosn += decode4to3( b4, 0, outBuff, outBuffPosn, options );
                        b4Posn = 0;
                        
                        // If that was the equals sign, break out of 'for' loop
                        if( sbiCrop == EQUALS_SIGN )
                            break;
                    }   // end if: quartet built
                    
                }   // end if: equals sign or better
                
            }   // end if: white space, equals sign or better
            else {
                System.err.println( "Bad Base64 input character at " + i + ": " + source[i] + "(decimal)" );
                return null;
            }   // end else:
        }   // each input character
        
        byte[] out = new byte[ outBuffPosn ];
        System.arraycopy( outBuff, 0, out, 0, outBuffPosn );
        return out;
    }   // end decode
    
    
    
    
    /**
     * Decodes data from Base64 notation, automatically
     * detecting gzip-compressed data and decompressing it.
     *
     * @param s the string to decode
     * @return the decoded data
     * @since 1.4
     */
    public static byte[] decode( String s ) {
        return decode( s, NO_OPTIONS );
    }
    
    
    /**
     * Decodes data from Base64 notation, automatically
     * detecting gzip-compressed data and decompressing it.
     *
     * @param s the string to decode
     * @param options encode options such as URL_SAFE
     * @return the decoded data
     * @since 1.4
     */
    public static byte[] decode( String s, int options ) {
        byte[] bytes;
        try {
            bytes = s.getBytes( PREFERRED_ENCODING );
        }   // end try
        catch( java.io.UnsupportedEncodingException uee ) {
            bytes = s.getBytes();
        }   // end catch
        //</change>
        
        // Decode
        bytes = decode( bytes, 0, bytes.length, options );
        
        
        // Check to see if it's gzip-compressed
        // GZIP Magic Two-Byte Number: 0x8b1f (35615)
        if( bytes != null && bytes.length >= 4 ) {
            
            int head = (bytes[0] & 0xff) | ((bytes[1] << 8) & 0xff00);
            if( java.util.zip.GZIPInputStream.GZIP_MAGIC == head ) {
                java.io.ByteArrayInputStream  bais = null;
                java.util.zip.GZIPInputStream gzis = null;
                java.io.ByteArrayOutputStream baos = null;
                byte[] buffer = new byte[2048];
                int    length = 0;
                
                try {
                    baos = new java.io.ByteArrayOutputStream();