binaryfilereader.java

来自「java 3d game jme 工程开发源代码」· Java 代码 · 共 243 行

/*
 * Copyright (c) 2003-2009 jMonkeyEngine
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 * * Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * * Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 *
 * * Neither the name of 'jMonkeyEngine' nor the names of its contributors 
 *   may be used to endorse or promote products derived from this software 
 *   without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package com.jme.util;

import java.io.DataInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.logging.Logger;

import com.jme.system.JmeException;

/**
 * <code>BinaryFileReader</code> provides a convienience class that wraps the
 * DataInputStream object for easier reading. Rather than having to deal with
 * a binary file one byte at a time, this class will handle reading: byte,
 * short, int, float and string. The file is read at the start, the file
 * stored as an array of bytes. An index into the array will keep track of
 * the reading point. The index can be manually adjusted via the
 * <code>setOffset</code> method.
 * @author Mark Powell
 * @version $Id: BinaryFileReader.java,v 1.12 2007/08/14 13:41:31 rherlitz Exp $
 */
public class BinaryFileReader {
    private static final Logger logger = Logger
            .getLogger(BinaryFileReader.class.getName());
    
	private byte[] fileContents;
	private int fileIndex = 0;
    private int markedPos = 0;

	/**
	 * Constructor creates a new <code>BinaryFileReader</code> class. This
	 * constructor takes the filename string as a parameter. This filename
	 * is converted into a URL and opened. If the filename is invalid, a
	 * <code>MalformedURLException</code> will be generated and logged.
	 * @param f the file to open.
	 */
	public BinaryFileReader(String f) {
		try {
			URL file = new URL(f);
			open(file);
		} catch (MalformedURLException e) {
			logger.warning("Could not open: " + f);
		}
	}

	/**
	 * Constructor instantiates a new <code>BinaryFileReader</code> object,
	 * loading the provided file and reading the data into a byte array.
	 * @param f the file to read.
	 */
	public BinaryFileReader(URL f) {
		open(f);
	}

    public BinaryFileReader(InputStream md2) {
        try {
            DataInputStream bis=new DataInputStream(md2);
            fileContents = new byte[bis.available()];
            bis.readFully(fileContents);
            bis.close();
        } catch (IOException e) {
            throw new JmeException("Could not read InputStream ");
        }
    }

    /**
	 *
	 * <code>open</code> opens a given URL stream. The data is read completely
	 * and the stream is then closed. This allows the stream to only be needed
	 * for the time it takes to read all the data, it is then closed.
	 *
	 * @param f the url pointing to the file to be read.
	 */
	public void open(URL f) {
		try {
			InputStream is = f.openStream();

			// wrap a buffer to make reading more efficient (faster)
			DataInputStream bis = new DataInputStream(is);

			fileContents = new byte[bis.available()];

			// Read the entire file into memory
			bis.readFully(fileContents);
			bis.close();
		} catch (IOException ioe) {
			throw new JmeException("Could not read: " + f);
		}
	}

	/**
	 *
	 * <code>readByte</code> reads a single byte from the array and
	 * returns this. The file index is then increased by one.
	 * @return the byte at the current index.
	 */
	public int readByte() {
		int b1 = (fileContents[fileIndex] & 0xFF);
		fileIndex += 1;
		return (b1);
	}

	/**
	 *
	 * <code>readShort</code> reads two bytes from the array, generating
	 * a short. The file index is then increased by two. The short is then
	 * inserted into an integer for convienience.
	 * @return the short at the current index.
	 */
	public int readShort() {
		int s1 = (fileContents[fileIndex] & 0xFF);
		int s2 = (fileContents[fileIndex + 1] & 0xFF) << 8;
		fileIndex += 2;
		return (s1 | s2);
	}

	public int readShort2() {
		int s1 = (fileContents[fileIndex + 1] & 0xFF);
		int s2 = (fileContents[fileIndex] & 0xFF) << 8;
		fileIndex += 2;
		return (s1 | s2);
	}

	/**
	 *
	 * <code>readInt</code> reads four bytes from the array, generating
	 * an int. The file index is then increased by four.
	 * @return the int at the currrent index.
	 */
	public int readInt() {
		int i1 = (fileContents[fileIndex] & 0xFF);
		int i2 = (fileContents[fileIndex + 1] & 0xFF) << 8;
		int i3 = (fileContents[fileIndex + 2] & 0xFF) << 16;
		int i4 = (fileContents[fileIndex + 3] & 0xFF) << 24;
		fileIndex += 4;
		return (i1 | i2 | i3 | i4);
	}

	/**
	 *
	 * <code>readFloat</code> reads four bytes from the array, generating
	 * a float. The file index is then increased by four.
	 * @return the float at the current index.
	 */
	public float readFloat() {
		return Float.intBitsToFloat(readInt());
	}

	/**
	 *
	 * <code>readString</code> reads a specified number of bytes to
	 * form a string. The length of the string (number of characters)
	 * is required to notify when reading should stop. The index is
	 * increased the number of characters read.
	 * @param size the length of the string to read.
	 * @return the string read.
	 */
	public String readString(int size) {
		//Look for zero terminated string from byte array
		for (int i = fileIndex; i < fileIndex + size; i++) {
			if (fileContents[i] == (byte) 0) {
				String s = new String(fileContents, fileIndex, i - fileIndex);
				fileIndex += size;
				return s;
			}
		}

		String s = new String(fileContents, fileIndex, size);
		fileIndex += size;
		return s;
	}

	/**
	 *
	 * <code>setOffset</code> sets the index of the file data.
	 * @param offset the new index of the file pointer.
	 */
	public void setOffset(int offset) {
		if (offset < 0 || offset > fileContents.length) {
			throw new JmeException("Illegal offset value. " + offset);
		}
		fileIndex = offset;
	}

    /**
     * Sets a mark for a later seekMarkOffset call.
     */
    public void markPos(){
        markedPos=fileIndex;
    }

    /**
     * Seeks to the position of the last mark + offset.
     * @param offset The Offset relative to mark.
     */
    public void seekMarkOffset(int offset){
        fileIndex=markedPos+offset;
        if (fileIndex < 0 || fileIndex > fileContents.length){
			throw new JmeException("Illegal offset value. " + offset);
		}
    }

    /**
     * Reads a signed short value.
     * @return The signed short.
     */ 
    public short readSignedShort() {
        return (short) readShort();
    }
}