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

                        // Read four "meaningful" bytes:
                        int b = 0;
                        do {
                            b = in.read();
                        }
                        while (b >= 0 && DECODABET[b & 0x7f] <= WHITE_SPACE_ENC);

                        if (b < 0)
                            break; // Reads a -1 if end of stream

                        b4[i] = (byte)b;
                    }   // end for: each needed input byte

                    if (i == 4) {
                        numSigBytes = decode4to3(b4, 0, buffer, 0);
                        position = 0;
                    }   // end if: got four characters
                    else if (i == 0) {
                        return -1;
                    }   // end else if: also padded correctly
                    else {
                        // Must have broken out from above.
                        throw new java.io.IOException("Improperly padded Base64 input.");
                    }   // end

                }   // end else: decode
            }   // end else: get data

            // Got data?
            if (position >= 0) {
                // End of relevant data?
                if (/*!encode &&*/ position >= numSigBytes)
                    return -1;

                if (encode && breakLines && lineLength >= MAX_LINE_LENGTH) {
                    lineLength = 0;
                    return '\n';
                }   // end if
                else {
                    lineLength++;   // This isn't important when decoding
                    // but throwing an extra "if" seems
                    // just as wasteful.

                    int b = buffer[position++];

                    if (position >= bufferLength)
                        position = -1;

                    return b & 0xFF; // This is how you "cast" a byte that's
                    // intended to be unsigned.
                }   // end else
            }   // end if: position >= 0

            // Else error
            else {
                // When JDK1.4 is more accepted, use an assertion here.
                throw new java.io.IOException("Error in Base64 code reading stream.");
            }   // end else
        }   // end read


        /**
         * Calls {@link #read} repeatedly until the end of stream
         * is reached or <var>len</var> bytes are read.
         * Returns number of bytes read into array or -1 if
         * end of stream is encountered.
         *
         * @param dest array to hold values
         * @param off  offset for array
         * @param len  max number of bytes to read into array
         * @return bytes read into array or -1 if end of stream is encountered.
         * @since 1.3
         */
        public int read(byte[] dest, int off, int len) throws java.io.IOException {
            int i;
            int b;
            for (i = 0; i < len; i++) {
                b = read();

                //if( b < 0 && i == 0 )
                //    return -1;

                if (b >= 0)
                    dest[off + i] = (byte)b;
                else if (i == 0)
                    return -1;
                else
                    break; // Out of 'for' loop
            }   // end for: each byte read
            return i;
        }   // end read

    }   // end inner class InputStream

    /* ********  I N N E R   C L A S S   O U T P U T S T R E A M  ******** */


    /**
     * A outputStream will write data to another
     * {@link java.io.OutputStream}, given in the constructor,
     * and encode/decode to/from Base64 notation on the fly.
     *
     * @see Base64
     * @see java.io.FilterOutputStream
     * @since 1.3
     */
    public static class OutputStream extends java.io.FilterOutputStream {
        private int options;
        private boolean encode;
        private int position;
        private byte[] buffer;
        private int bufferLength;
        private int lineLength;
        private boolean breakLines;
        private byte[] b4; // Scratch used in a few places
        private boolean suspendEncoding;

        /**
         * Constructs a OutputStream in ENCODE mode.
         *
         * @param out the {@link java.io.OutputStream} to which data will be written.
         * @since 1.3
         */
        public OutputStream(java.io.OutputStream out) {
            this(out, ENCODE);
        }   // end constructor


        /**
         * Constructs a OutputStream in
         * either ENCODE or DECODE mode.
         * <p/>
         * Valid options:<pre>
         *   ENCODE or DECODE: Encode or Decode as data is read.
         *   DONT_BREAK_LINES: don't break lines at 76 characters
         *     (only meaningful when encoding)
         *     <i>Note: Technically, this makes your encoding non-compliant.</i>
         * </pre>
         * <p/>
         * Example: <code>new Base64.OutputStream( out, Base64.ENCODE )</code>
         *
         * @param out     the {@link java.io.OutputStream} to which data will be written.
         * @param options Specified options.
         * @see Base64#ENCODE
         * @see Base64#DECODE
         * @see Base64#DONT_BREAK_LINES
         * @since 1.3
         */
        public OutputStream(java.io.OutputStream out, int options) {
            super(out);
            this.options = options;
            this.breakLines = (options & DONT_BREAK_LINES) != DONT_BREAK_LINES;
            this.encode = (options & ENCODE) == ENCODE;
            this.bufferLength = encode ? 3 : 4;
            this.buffer = new byte[bufferLength];
            this.position = 0;
            this.lineLength = 0;
            this.suspendEncoding = false;
            this.b4 = new byte[4];
        }   // end constructor


        /**
         * Writes the byte to the output stream after
         * converting to/from Base64 notation.
         * When encoding, bytes are buffered three
         * at a time before the output stream actually
         * gets a write() call.
         * When decoding, bytes are buffered four
         * at a time.
         *
         * @param theByte the byte to write
         * @since 1.3
         */
        public void write(int theByte) throws java.io.IOException {
            // Encoding suspended?
            if (suspendEncoding) {
                super.out.write(theByte);
                return;
            }   // end if: supsended

            // Encode?
            if (encode) {
                buffer[position++] = (byte)theByte;
                if (position >= bufferLength)  // Enough to encode.
                {
                    out.write(encode3to4(b4, buffer, bufferLength));

                    lineLength += 4;
                    if (breakLines && lineLength >= MAX_LINE_LENGTH) {
                        out.write(NEW_LINE);
                        lineLength = 0;
                    }   // end if: end of line

                    position = 0;
                }   // end if: enough to output
            }   // end if: encoding

            // Else, Decoding
            else {
                // Meaningful Base64 character?
                if (DECODABET[theByte & 0x7f] > WHITE_SPACE_ENC) {
                    buffer[position++] = (byte)theByte;
                    if (position >= bufferLength)  // Enough to output.
                    {
                        int len = Base64.decode4to3(buffer, 0, b4, 0);
                        out.write(b4, 0, len);
                        //out.write( Base64.decode4to3( buffer ) );
                        position = 0;
                    }   // end if: enough to output
                }   // end if: meaningful base64 character
                else if (DECODABET[theByte & 0x7f] != WHITE_SPACE_ENC) {
                    throw new java.io.IOException("Invalid character in Base64 data.");
                }   // end else: not white space either
            }   // end else: decoding
        }   // end write


        /**
         * Calls {@link #write} repeatedly until <var>len</var>
         * bytes are written.
         *
         * @param theBytes array from which to read bytes
         * @param off      offset for array
         * @param len      max number of bytes to read into array
         * @since 1.3
         */
        public void write(byte[] theBytes, int off, int len) throws java.io.IOException {
            // Encoding suspended?
            if (suspendEncoding) {
                super.out.write(theBytes, off, len);
                return;
            }   // end if: supsended

            for (int i = 0; i < len; i++) {
                write(theBytes[off + i]);
            }   // end for: each byte written

        }   // end write


        /**
         * Method added by PHIL. [Thanks, PHIL. -Rob]
         * This pads the buffer without closing the stream.
         */
        public void flushBase64() throws java.io.IOException {
            if (position > 0) {
                if (encode) {
                    out.write(encode3to4(b4, buffer, position));
                    position = 0;
                }   // end if: encoding
                else {
                    throw new java.io.IOException("Base64 input not properly padded.");
                }   // end else: decoding
            }   // end if: buffer partially full

        }   // end flush


        /**
         * Flushes and closes (I think, in the superclass) the stream.
         *
         * @since 1.3
         */
        public void close() throws java.io.IOException {
            // 1. Ensure that pending characters are written
            flushBase64();

            // 2. Actually close the stream
            // Base class both flushes and closes.
            super.close();

            buffer = null;
            out = null;
        }   // end close


        /**
         * Suspends encoding of the stream.
         * May be helpful if you need to embed a piece of
         * base640-encoded data in a stream.
         *
         * @since 1.5.1
         */
        public void suspendEncoding() throws java.io.IOException {
            flushBase64();
            this.suspendEncoding = true;
        }   // end suspendEncoding


        /**
         * Resumes encoding of the stream.
         * May be helpful if you need to embed a piece of
         * base640-encoded data in a stream.
         *
         * @since 1.5.1
         */
        public void resumeEncoding() {
            this.suspendEncoding = false;
        }   // end resumeEncoding


    }   // end inner class OutputStream


}   // end class Base64