Author: gaohoward Date: 2010-11-29 09:15:10 -0500 (Mon, 29 Nov 2010) New Revision: 9937 Added: branches/Branch_Large_Message_Compression/src/main/org/hornetq/utils/DeflaterReader.java Log: added a zip class impl that directly use Deflater Added: branches/Branch_Large_Message_Compression/src/main/org/hornetq/utils/DeflaterReader.java =================================================================== --- branches/Branch_Large_Message_Compression/src/main/org/hornetq/utils/DeflaterReader.java (rev 0) +++ branches/Branch_Large_Message_Compression/src/main/org/hornetq/utils/DeflaterReader.java 2010-11-29 14:15:10 UTC (rev 9937) @@ -0,0 +1,158 @@ +/* + * Copyright 2010 Red Hat, Inc. + * Red Hat licenses this file to you under the Apache License, version + * 2.0 (the "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * http://www.apache.org/licenses/LICENSE-2.0 + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or + * implied. See the License for the specific language governing + * permissions and limitations under the License. + */ + +package org.hornetq.utils; + +import java.io.ByteArrayInputStream; +import java.io.IOException; +import java.io.InputStream; +import java.util.zip.Deflater; + +/** + * A DeflaterReader + * The reader takes an inputstream and compress it. + * + * + */ +public class DeflaterReader +{ + private Deflater deflater = new Deflater(); + private boolean isFinished = false; + private boolean compressDone = false; + + private InputStream input; + + public DeflaterReader(InputStream inData) + { + input = inData; + } + + public int read(byte[] buffer) throws IOException + { + return read(buffer, 0, buffer.length); + } + + /** + * Try to fill the buffer with compressed bytes. Except the last effective read, + * this method always returns with a full buffer of compressed data. + * + * @param buffer the buffer to fill compressed bytes + * @return the number of bytes really filled, -1 indicates end. + * @throws IOException + */ + public int read(byte[] buffer, int offset, int len) throws IOException + { + if (compressDone) + { + return -1; + } + + //buffer for reading input stream + byte[] readBuffer = new byte[2 * len]; + + int n = 0; + int read = 0; + + while (len > 0) + { + n = deflater.deflate(buffer, offset, len); + if (n == 0) + { + if (isFinished) + { + deflater.end(); + compressDone = true; + break; + } + else if (deflater.needsInput()) + { + System.err.println("need input so read input"); + // read some data from inputstream + int m = input.read(readBuffer); + System.err.println("original data read: " + m); + if (m == -1) + { + System.err.println("no more original data, finish deflater, now offset " + offset + " len " + len); + + deflater.finish(); + isFinished = true; + } + else + { + deflater.setInput(readBuffer, 0, m); + } + } + else + { + deflater.finish(); + isFinished = true; + } + } + else + { + read += n; + offset += n; + len -= n; + } + + } + return read; + } + + public static void main(String[] args) throws IOException + { + String inputString = "blahblahblah??blahblahblahblahblah??blablahblah??blablahblah??bla"; + byte[] input = inputString.getBytes("UTF-8"); + + ByteArrayInputStream inputStream = new ByteArrayInputStream(input); + + DeflaterReader reader = new DeflaterReader(inputStream); + + byte[] buffer = new byte[7]; + + int n = reader.read(buffer); + + System.err.println("first read: " + n); + + while (n != -1) + { + System.err.println("==>read n " + n + " values: " + getBytesString(buffer)); + n = reader.read(buffer); + } + + System.err.println("compressed."); + + System.err.println("now verify"); + + byte[] output = new byte[30]; + Deflater compresser = new Deflater(); + compresser.setInput(input); + compresser.finish(); + int compressedDataLength = compresser.deflate(output); + System.err.println("compress len: " + compressedDataLength); + System.err.println("commpress data: " + getBytesString(output)); + + } + + static String getBytesString(byte[] array) + { + StringBuffer bf = new StringBuffer(); + for (byte b : array) + { + int val = b & 0xFF; + bf.append(val + " "); + } + return bf.toString(); + } + +}