With this example we are going to demonstrate how to compress and expand an Object. We have implemented the ObjectCompressionUtil Class, that extends the Serializable class and has a parameter that is the generic type of the serializable object to be compressed. The class consists of two methods.
- The
- Creates a new GZIPOutputStream with a default buffer size.
- Creates an ObjectOutputStream that writes to the specified GZIPOutputStream.
- Writes the specified object to be compressed to the ObjectOutputStream and flush it, using
writeObject(Object obj)andflush()API methods of ObjectOutputStream. - Closes both the GZIPOutputStream and the ObjectOutputStream, using their
close()API methods.
compressObject(final T objectToCompress, final OutputStream outstream) takes the object to compress and an OutputStream and returns the compressed object, as described below:- The
- Creates a new GZIPInputStream with a default buffer size.
- Creates an ObjectInputStream that reads from the specified GZIPInputStream.
- Reads the object to expand from the ObjectInputStream, with
readObject()API method of ObjectInputStream. - Returns the expanded object and closes both the GZIPInputStream and the ObjectInputStream, using their
close()API methods.
expandObject(final T objectToExpand, final InputStream instream) method takes the object to expand and an InputStream and returns the expanded object, as shown below:Let’s take a look at the code snippet that follows:
package javaitzen.blog;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.OutputStream;
import java.io.Serializable;
import java.util.zip.GZIPInputStream;
import java.util.zip.GZIPOutputStream;
/**
* The Class ObjectCompressionUtil.
*
* @param <T> the generic type of the serializable object to be compressed
*/
public class ObjectCompressionUtil<T extends Serializable> {
/**
* Compress object.
*
* @param objectToCompress the object to compress
* @param outstream the outstream
* @return the compressed object
* @throws IOException Signals that an I/O exception has occurred.
*/
public T compressObject(final T objectToCompress, final OutputStream outstream) throws IOException {
final GZIPOutputStream gz = new GZIPOutputStream(outstream);
final ObjectOutputStream oos = new ObjectOutputStream(gz);
try {
oos.writeObject(objectToCompress);
oos.flush();
return objectToCompress;
}finally {
oos.close();
outstream.close();
}
}
/**
* Expand object.
*
* @param objectToExpand the object to expand
* @param instream the instream
* @return the expanded object
* @throws IOException Signals that an I/O exception has occurred.
* @throws ClassNotFoundException the class not found exception
*/
public T expandObject(final T objectToExpand, final InputStream instream) throws IOException,
ClassNotFoundException {
final GZIPInputStream gs = new GZIPInputStream(instream);
final ObjectInputStream ois = new ObjectInputStream(gs);
try {
@SuppressWarnings("unchecked")
T expandedObject = (T) ois.readObject();
return expandedObject;
} finally {
gs.close();
ois.close();
}
}
}
Related Article:
Reference: Java Compression from our JCG partner Brian at Zen in the art of IT
This was an example of how to compress and expand an Object in Java.
