MyBufferedInputStream.java

package org.amse.ys.zip;

import java.io.*;

import org.geometerplus.fbreader.formats.txt.JustEncoding;

final class MyBufferedInputStream extends InputStream {
    private final ZipFile.InputStreamHolder myStreamHolder;
    private InputStream myFileInputStream;
    private final byte[] myBuffer;
    int myBytesReady;
    int myPositionInBuffer;
    private int myCurrentPosition;
    
    public MyBufferedInputStream(ZipFile.InputStreamHolder streamHolder, int bufferSize) throws IOException {
        myStreamHolder = streamHolder;
        myFileInputStream = streamHolder.getInputStream();
        myBuffer = new byte[bufferSize];
        myBytesReady = 0;
        myPositionInBuffer = 0;
    }

    public MyBufferedInputStream(ZipFile.InputStreamHolder streamHolder) throws IOException {
        this(streamHolder, 1 << 10);
    }

    public int available() throws IOException {
        return (myFileInputStream.available() + myBytesReady);
    }

    int offset() {
        return myCurrentPosition;
    }

    public int read(byte[] b, int off, int len) throws IOException {        
		int ready = (len < myBytesReady) ? len : myBytesReady;
		if (ready > 0) {
			System.arraycopy(myBuffer, myPositionInBuffer, b, off, ready);
			len -= ready;
			myBytesReady -= ready;
			myPositionInBuffer += ready;
			off += ready;
		}
		if (len > 0) {
			final int ready2 = myFileInputStream.read(b, off, len);
			if (ready2 >= 0) {
				ready += ready2;
			}
		}
		myCurrentPosition += ready;
		return (ready > 0) ? ready : -1;
	}

    public int read() throws IOException {        
        myCurrentPosition++;
        if (myBytesReady <= 0) {
            myPositionInBuffer = 0;
            myBytesReady = myFileInputStream.read(myBuffer);
            if (myBytesReady <= 0) {
                return -1;
            }
        }        
        myBytesReady--;        
        return myBuffer[myPositionInBuffer++] & 255;        
    }
    //hym 加，为了处理 文件名是中文的问题
    public byte read(boolean flag) throws IOException {        
        myCurrentPosition++;
        if (myBytesReady <= 0) {
            myPositionInBuffer = 0;
            myBytesReady = myFileInputStream.read(myBuffer);
            if (myBytesReady <= 0) {
                return -1;
            }
        }        
        myBytesReady--;        
        return myBuffer[myPositionInBuffer++] ;        
    }
    int read2Bytes() throws IOException {
        int low = read();
        int high = read();
        if (high < 0) {
            throw new IOException("unexpected end of file at position " + offset());
        }
        return (high << 8) + low;
    }

    int read4Bytes() throws IOException {
        int firstByte = read();
        int secondByte = read();
        int thirdByte = read();
        int fourthByte = read();
        if (fourthByte < 0) {
            throw new IOException("unexpected end of file at position " + offset());
        }
        return (fourthByte << 24) + (thirdByte << 16) + (secondByte << 8) + firstByte;
    }

    String readString(int stringLength) throws IOException {
        char[] array = new char[stringLength];
        for (int i = 0; i < stringLength; i++) {
            array[i] = (char)read();
        }
        return new String(array);
    }
    String readString(int stringLength,boolean flag) throws IOException {
        byte[] array = new byte[stringLength];
        for (int i = 0; i < stringLength; i++) {
            array[i] = (byte)read(flag);
        }
      //hym 加，为了处理 文件名是中文的问题
        int enc = new JustEncoding().detectEncoding(array);
//        System.out.println("-------hhh:"+enc);
        
        return new String(array,JustEncoding.nicename[enc]);
    }
    public void skip(int n) throws IOException {
        myCurrentPosition += n;
        if (myBytesReady >= n) {
            myBytesReady -= n;
            myPositionInBuffer += n;
        } else {
            n -= myBytesReady;
            myBytesReady = 0;

            if (n > myFileInputStream.available()) {
                throw new IOException("Not enough bytes to read");
            }
            n -= myFileInputStream.skip(n);
            while (n > 0) {
                int skipped = myFileInputStream.read(myBuffer, 0, Math.min(n, myBuffer.length));
                if (skipped <= 0) {
                    throw new IOException("Not enough bytes to read");
                }
                n -= skipped;
            }
        }
    }

    public void backSkip(int n) throws IOException {
		if (n <= 0) {
			return;
		}
        myFileInputStream.close();
        myFileInputStream = myStreamHolder.getInputStream();
        myBytesReady = 0;
		myPositionInBuffer = 0;
		int position = myCurrentPosition - n;
		myCurrentPosition = 0;
        skip(position);
    }

    public void setPosition(int position) throws IOException {
        if (myCurrentPosition < position) {
            skip(position - myCurrentPosition);
        } else {
			backSkip(myCurrentPosition - position);
        }
    }

	/*
    public void setPosition(int position) throws IOException {
        if (myCurrentPosition < position) {
            skip(position - myCurrentPosition);
        } else {
            myFileInputStream.close();
            myFileInputStream = myStreamHolder.getInputStream();
            myBytesReady = 0;
            skip(position);
        	myCurrentPosition = position;
        }
    }
	*/

    public void close() throws IOException {
        myFileInputStream.close();
        myBytesReady = 0;
    }
}