peekinputstream.java

来自「Messaging- MIDP的是一个彩信客户端」· Java 代码 · 共 86 行

/*
 *  JVending - J2ME MMS Client
 *  Copyright (C) 2004  Shane Isbell
 *
 *  This library 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 2.1 of the License, or (at your option) any later version.
 *
 *  This library 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 this library; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package org.jvending.messaging.impl.io;

import java.io.InputStream;
import java.io.IOException;

import org.jvending.messaging.impl.mms.SimpleQueue;

/**
 * @author Shane Isbell
 * @version 1.0.2a
 * @since 04/03/28
 */

public class PeekInputStream {
    
    private InputStream dis;

    private int bufferSize;

    private SimpleQueue peekQueue;

    public PeekInputStream(InputStream is) {
          this.dis = is;
        bufferSize = 5;
        peekQueue = new SimpleQueue(bufferSize);
    }

    public PeekInputStream(InputStream is, int bufferSize) {
          this.dis = is;
        this.bufferSize = bufferSize;
        peekQueue = new SimpleQueue(bufferSize);
    }

    public int readUnsignedByte() throws IOException {
        return this.readByte();
    }

    public int read(byte[] b, int off, int len) throws IOException {
        return dis.read(b, off, len);
    }

    public int readByte() throws IOException {//was readByte()
        if(peekQueue.isEmpty()) {
            return dis.read();
        } else {
            return ((Integer) peekQueue.dequeue()).intValue();
        }
    }

    public void clearQueue() {
        peekQueue = new SimpleQueue(bufferSize);
    }

    public int peekUnsignedByte(int look) throws IOException, IndexOutOfBoundsException {
        return (peekByte(look) & 0x7f);
    }

    //needs more work
    public int peekByte(int look) throws IOException, IndexOutOfBoundsException {
          int b = 0;
        for(int i = 0; i < look; i++) {
            b = dis.read();
            if(b != -1) peekQueue.enqueue(new Integer(b));
        }       
        return b;
    }
}