BE-Graphes/src/main/org/insa/graph/io/BinaryReader.java
2018-03-01 13:33:56 +01:00

90 lines
2.4 KiB
Java

package org.insa.graph.io;
import java.io.DataInputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
public abstract class BinaryReader {
// Map version and magic number targeted for this reader.
private int minVersion;
private int curVersion;
private int magicNumber;
// InputStream
protected DataInputStream dis;
// List of observers
protected List<GraphReaderObserver> observers = new ArrayList<>();
protected BinaryReader(int magicNumber, int minVersion, DataInputStream dis) {
this.magicNumber = magicNumber;
this.minVersion = minVersion;
this.dis = dis;
}
/**
* {@inheritDoc}
*/
public void addObserver(GraphReaderObserver observer) {
observers.add(observer);
}
/**
* Check if the given version is greater than the minimum version, and update
* the current version if it is.
*
* @param version
* @throws BadVersionException
*/
protected void checkVersionOrThrow(int version) throws BadVersionException {
if (version < this.minVersion) {
throw new BadVersionException(version, this.minVersion);
}
this.curVersion = version;
}
/**
* @return the current version.
*/
protected int getCurrentVersion() {
return this.curVersion;
}
/**
* @param magicNumber
* @throws BadMagicNumberException
*/
protected void checkMagicNumberOrThrow(int magicNumber) throws BadMagicNumberException {
if (this.magicNumber != magicNumber) {
throw new BadMagicNumberException(magicNumber, this.magicNumber);
}
}
/**
* Check if the next byte in the input stream correspond to the given byte. This
* function consumes the next byte in the input stream.
*
* @param i Byte to check against.
*
* @throws IOException
*/
protected void checkByteOrThrow(int i) throws IOException {
if (dis.readUnsignedByte() != i) {
throw new BadFormatException();
}
}
/**
* Read 24 bits from the stream and return the corresponding integer value.
*
* @return Integer value read from the next 24 bits of the stream.
*
* @throws IOException
*/
protected int read24bits() throws IOException {
int x = dis.readUnsignedShort();
return (x << 8) | dis.readUnsignedByte();
}
}