base64.java

用Java开发的、实现类似Visio功能的应用程序源码

        java.util.zip.GZIPOutputStream gzos  = null;
        
        // Isolate options
        int gzip           = (options & GZIP);
        int dontBreakLines = (options & DONT_BREAK_LINES);
        
        try
        {
            // ObjectOutputStream -> (GZIP) -> Base64 -> ByteArrayOutputStream
            baos  = new java.io.ByteArrayOutputStream();
            b64os = new Base64.OutputStream( baos, ENCODE | dontBreakLines );
    
            // GZip?
            if( gzip == GZIP )
            {
                gzos = new java.util.zip.GZIPOutputStream( b64os );
                oos  = new java.io.ObjectOutputStream( gzos );
            }   // end if: gzip
            else
                oos   = new java.io.ObjectOutputStream( b64os );
            
            oos.writeObject( serializableObject );
        }   // end try
        catch( java.io.IOException e )
        {
            e.printStackTrace();
            return null;
        }   // end catch
        finally
        {
            try{ oos.close();   } catch( Exception e ){}
            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 encode
    
    

    /**
     * Encodes a byte array into Base64 notation.
     * Does not GZip-compress data.
     *
     * @param source The data to convert
     */
    public static String encodeBytes( byte[] source )
    {
        return encodeBytes( source, 0, source.length, 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 options Specified options
     */
    public static String encodeBytes( byte[] source, int options )
    {   
        return encodeBytes( source, 0, source.length, options );
    }   // end encodeBytes
    
    
    /**
     * Encodes a byte array into Base64 notation.
     * Does not GZip-compress data.
     *
     * @param source The data to convert
     * @param off Offset in array where conversion should begin
     * @param len Length of data to convert
     */
    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 breakLines Break lines at 80 characters or less.
     * @param options Specified options
     */
    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 | dontBreakLines );
                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 );

                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 );
                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 the first four bytes of array <var>fourBytes</var>
     * and returns an array up to three bytes long with the
     * decoded values.
     *
     * @param fourBytes the array with Base64 content
     * @return array with decoded values
     */
    private static byte[] decode4to3( byte[] fourBytes )
    {
        byte[] outBuff1 = new byte[3];
        int    count    = decode4to3( fourBytes, 0, outBuff1, 0 );
        byte[] outBuff2 = new byte[ count ];
        
        for( int i = 0; i < count; i++ )
            outBuff2[i] = outBuff1[i];
        
        return outBuff2;
    }
    
    
    
    
    /**
     * 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.
     * 
     *
     * @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
     * @return the number of decoded bytes converted
     */
    private static int decode4to3( byte[] source, int srcOffset, byte[] destination, int destOffset )
    {
        // 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){