IntReader.java

package com.baidu.luxiaoyu;

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

/**
 * 
 * Simple helper class that allows reading of integers.
 * 
 * TODO: * implement buffering
 * 
 */
public final class IntReader {

    public IntReader() {
    }

    public IntReader(InputStream stream, boolean bigEndian) {
        reset(stream, bigEndian);
    }

    public final void reset(InputStream stream, boolean bigEndian) {
        m_stream = stream;
        m_bigEndian = bigEndian;
        m_position = 0;
    }

    public final void close() {
        if (m_stream == null) {
            return;
        }
        try {
            m_stream.close();
        } catch (IOException e) {
        }
        reset(null, false);
    }

    public final InputStream getStream() {
        return m_stream;
    }

    public final boolean isBigEndian() {
        return m_bigEndian;
    }

    public final void setBigEndian(boolean bigEndian) {
        m_bigEndian = bigEndian;
    }

    public final int readByte() throws IOException {
        return readInt(1);
    }

    public final int readShort() throws IOException {
        return readInt(2);
    }

    public final int readInt() throws IOException {
        return readInt(4);
    }

    public final int readInt(int length) throws IOException {
        if (length < 0 || length > 4) {
            throw new IllegalArgumentException();
        }
        int result = 0;
        if (m_bigEndian) {
            for (int i = (length - 1) * 8; i >= 0; i -= 8) {
                int b = m_stream.read();
                if (b == -1) {
                    throw new EOFException();
                }
                m_position += 1;
                result |= (b << i);
            }
        } else {
            length *= 8;
            for (int i = 0; i != length; i += 8) {
                int b = m_stream.read();
                if (b == -1) {
                    throw new EOFException();
                }
                m_position += 1;
                result |= (b << i);
            }
        }
        return result;
    }

    public final int[] readIntArray(int length) throws IOException {
        int[] array = new int[length];
        readIntArray(array, 0, length);
        return array;
    }

    public final void readIntArray(int[] array, int offset, int length) throws IOException {
        for (; length > 0; length -= 1) {
            array[offset++] = readInt();
        }
    }

    public final byte[] readByteArray(int length) throws IOException {
        byte[] array = new byte[length];
        int read = m_stream.read(array);
        m_position += read;
        if (read != length) {
            throw new EOFException();
        }
        return array;
    }

    public final void skip(int bytes) throws IOException {
        if (bytes <= 0) {
            return;
        }
        long skipped = m_stream.skip(bytes);
        m_position += skipped;
        if (skipped != bytes) {
            throw new EOFException();
        }
    }

    public final void skipInt() throws IOException {
        skip(4);
    }

    public final int available() throws IOException {
        return m_stream.available();
    }

    public final int getPosition() {
        return m_position;
    }

    /////////////////////////////////// data

    private InputStream m_stream;
    private boolean     m_bigEndian;
    private int         m_position;
}