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A library to read PST files with java, without need for external libraries.
There is a newer version: 0.9.3
/*
 * Copyright 2010 Richard Johnson & Orin Eman
 *
 * Licensed 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.
 *
 * ---
 *
 * This file is part of java-libpst.
 *
 * java-libpst is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * java-libpst is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with java-libpst.  If not, see .
 *
 */

package com.pff;

import java.io.UnsupportedEncodingException;

/**
 * An implementation of the LZFu algorithm to decompress RTF content
 * @author Richard Johnson
 */
public class LZFu {

	public static final String LZFU_HEADER = "{\\rtf1\\ansi\\mac\\deff0\\deftab720{\\fonttbl;}{\\f0\\fnil \\froman \\fswiss \\fmodern \\fscript \\fdecor MS Sans SerifSymbolArialTimes New RomanCourier{\\colortbl\\red0\\green0\\blue0\n\r\\par \\pard\\plain\\f0\\fs20\\b\\i\\u\\tab\\tx";

	public static String decode(byte[] data)
			throws PSTException
	{

		@SuppressWarnings("unused")
		int compressedSize = (int)PSTObject.convertLittleEndianBytesToLong(data, 0, 4);
		int uncompressedSize = (int)PSTObject.convertLittleEndianBytesToLong(data, 4, 8);
		int compressionSig =  (int)PSTObject.convertLittleEndianBytesToLong(data, 8, 12);
		@SuppressWarnings("unused")
		int compressedCRC =  (int)PSTObject.convertLittleEndianBytesToLong(data, 12, 16);

		if (compressionSig == 0x75465a4c) {
			// we are compressed...
			byte[] output = new byte[uncompressedSize];
			int outputPosition = 0;
			byte[] lzBuffer = new byte[4096];
			// preload our buffer.
			try {
				byte[] bytes = LZFU_HEADER.getBytes("US-ASCII");
				System.arraycopy(bytes, 0, lzBuffer, 0, LZFU_HEADER.length());
			} catch (UnsupportedEncodingException e) {
				e.printStackTrace();
			}
			int bufferPosition = LZFU_HEADER.length();
			int currentDataPosition = 16;

			// next byte is the flags,
			while (currentDataPosition < data.length - 2 && outputPosition < output.length) {
				int flags = data[currentDataPosition++] & 0xFF;
				for (int x = 0; x < 8 && outputPosition < output.length; x++) {
					boolean isRef = ((flags & 1) == 1);
					flags >>= 1;
					if (isRef) {
						// get the starting point for the buffer and the
						// length to read
						int refOffsetOrig = data[currentDataPosition++] & 0xFF;
						int refSizeOrig = data[currentDataPosition++] & 0xFF;
						int refOffset = (refOffsetOrig << 4) | (refSizeOrig >>> 4);
						int refSize = (refSizeOrig & 0xF) + 2;
						//refOffset &= 0xFFF;
						try {
							// copy the data from the buffer
							int index = refOffset;
							for (int y = 0; y < refSize && outputPosition < output.length; y++) {
								output[outputPosition++] = lzBuffer[index];
								lzBuffer[bufferPosition] = lzBuffer[index];
								bufferPosition++;
								bufferPosition %= 4096;
								++index;
								index %= 4096;
							}
						} catch ( Exception e ) {
							e.printStackTrace();
						}

					} else {
						// copy the byte over
						lzBuffer[bufferPosition] = 	data[currentDataPosition];
						bufferPosition++;
						bufferPosition %= 4096;
						output[outputPosition++] = data[currentDataPosition++];
					}
				}
			}

			if ( outputPosition != uncompressedSize ) {
				throw new PSTException(String.format("Error decompressing RTF! Expected %d bytes, got %d bytes\n", uncompressedSize, outputPosition));
			}
			return new String(output).trim();

		} else if (compressionSig == 0x414c454d) {
			// we are not compressed!
			// just return the rest of the contents as a string
			byte[] output = new byte[data.length-16];
			System.arraycopy(data, 16, output, 0, data.length-16);
			return new String(output).trim();
		}

		return "";
	}
}