Byte Array Buffer

This class allows access to an array of bytes so that you can read and write primitives and sub-arrays of bytes from it. I find it useful and while written before NIO I feel there are some advantaged over mapped buffers.

I am not sure this is an answer to a frequently asked question but if you have ever needed something like this it does come in awfully handy.

/* This is free to use without restrictions of any kind. No warranty implied aka use at your own risk. Author : Max Stocker Note : This header can certainly be removed I just want to make clear that this is my orginial work and not taken from elsewhere */ import java.io.IOException; /** The Bufferedpage class provides buffered read and write access to a page of data. Basically reading and writing of all primitives are supported and there are special methods for reading and writing blocks (byte[]) of data at a time. */ public final class Bufferedpage{ private boolean needsFlush; private byte[] buff; private int pos; /** Creates a new empty size buffered page. */ public Bufferedpage(){ buff = new byte[0]; needsFlush = false; pos = 0; } /** Creates a buffered page of the given size. */ public Bufferedpage(int initialsize){ buff = new byte[initialsize]; for(int i=0;i<buff.length;i++){ buff[i] = 0x00; } needsFlush = false; pos = 0; } /** Sets the buffer content to be toLoad. */ public void loadBuffer(byte[] toLoad){ buff = toLoad; needsFlush = false; pos = 0; } /** Returns the contents of the buffer as a byte array. This resets the needsFlush flag.*/ public byte[] getBufferContents(){ needsFlush = false; return buff; } /** Returns true if this buffer needs to be flushed. This will return true if any write operations were called on the buffer contents.*/ public boolean bufferNeedsFlush(){ return needsFlush; } /** Seeks to the position in the buffer. */ public void seek(int position){ pos = position; if(pos<0){ pos = 0; } } /** Returns the current position in the buffer. */ public int getPosition(){ return pos; } /** Returns the size of the current buffer. */ public int getSize(){ return buff.length; } /** Returns an int read from the current position. */ public int readInt()throws IOException{ int ch1 = readByte(); int ch2 = readByte(); int ch3 = readByte(); int ch4 = readByte(); return ((ch1 << 24) & 0xFF000000) + ((ch2 << 16) & 0x00FF0000) + ((ch3 << 8) & 0x0000FF00) + ((ch4 << 0) & 0x000000FF); } /** Returns a byte read from the current position. */ public byte readByte()throws IOException{ if(pos>=buff.length){ throw new IOException("Buffer Overflow Exception"); } byte tr = buff[pos]; pos++; return tr; } /** Returns a long read from the current position. */ public long readLong()throws IOException{ return ((long)(readInt()) << 32) + (readInt() & 0xFFFFFFFFL); } /** Returns a float read from the current position. */ public float readFloat()throws IOException{ return Float.intBitsToFloat(readInt()); } /** Returns a double read from the current position. */ public double readDouble()throws IOException{ return Double.longBitsToDouble(readLong()); } /** Returns a short read from the current position. */ public short readShort()throws IOException{ byte ch1 = readByte(); byte ch2 = readByte(); return (short)(((ch1 << 8 )& 0x0000FF00) + ((ch2 << 0)& 0x000000FF)); } /** Returns a boolean read from the current position. */ public boolean readBoolean()throws IOException{ return (readByte()==0x01); } /** Writes the byte b starting at the current position. */ public void writeByte(byte b)throws IOException{ write(b); } /** Writes the short s starting at the current position. */ public void writeShort(short s)throws IOException{ write((byte)((s >>> 8) & 0xFF)); write((byte)((s >>> 0) & 0xFF)); } /** Writes the int v starting at the current position. */ public void writeInt(int v)throws IOException{ write((byte)((v >>> 24) & 0xFF)); write((byte)((v >>> 16) & 0xFF)); write((byte)((v >>> 8) & 0xFF)); write((byte)((v >>> 0) & 0xFF)); } /** Writes the long v starting at the current position. */ public void writeLong(long v)throws IOException{ write((byte)((v >>> 56) & 0xFF)); write((byte)((v >>> 48) & 0xFF)); write((byte)((v >>> 40) & 0xFF)); write((byte)((v >>> 32) & 0xFF)); write((byte)((v >>> 24) & 0xFF)); write((byte)((v >>> 16) & 0xFF)); write((byte)((v >>> 8) & 0xFF)); write((byte)((v >>> 0) & 0xFF)); } /** Writes the float v starting at the current position. */ public void writeFloat(float v)throws IOException{ writeInt(Float.floatToIntBits(v)); } /** Writes the double v starting at the current position. */ public void writeDouble(double v)throws IOException{ writeLong(Double.doubleToLongBits(v)); } /** Writes the boolean b starting at the current position. */ public void writeBoolean(boolean b)throws IOException{ if(b){ writeByte((byte)0x01); }else{ writeByte((byte)0x00); } } /** Reads an array of bytes from the buffer. This method is more efficent than reading individual bytes because it uses System.arraycopy instead of reading byte by byte. */ public byte[] readBytes(int size)throws IOException{ if((buff.length-pos)<size){ throw new IOException("Buffer Overflow Exception"); } byte[] temp = new byte[size]; System.arraycopy(buff,pos,temp,0,size); return temp; } /** Writes an array of bytes to the buffer starting at the current position. */ public void writeBytes(byte[] b)throws IOException{ if((buff.length-pos)<b.length){ throw new IOException("Buffer Overflow Exception"); } System.arraycopy(b,0,buff,pos,b.length); needsFlush = true; } private void write(byte b)throws IOException{ if(pos>=buff.length){ throw new IOException("Buffer Overflow Exception"); } buff[pos] = b; pos++; needsFlush = true; } }

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