Java Journal!

Today, I have to write Java utility for resizing JPEG images for my photo gallary. It wasn’t so easy, because to resize is really stupid task. But what about smoothing of result images. They used to become absolutely unsuitable for posting to my web-site.

I found solution and glad to open a source code:

private void resizeImage(String filename, String newfilename)
	throws InterruptedException, ImageFormatException, IOException
{
	LOG.info("Resizing file : " + filename);
	// load image from file
	Image image = Toolkit.getDefaultToolkit().getImage(filename);
	MediaTracker mediaTracker = new MediaTracker(new Container());
	mediaTracker.addImage(image, 0);
	mediaTracker.waitForID(0);

	// get real size
	int imageWidth = image.getWidth(null);
	int imageHeight = image.getHeight(null);
	double imageRatio = (double)imageWidth / (double)imageHeight;

	// determine - vertical or horizontal
	if(imageHeight > imageWidth) {
		// vertical
		imageHeight = biggerPart;
		imageWidth = (int)(imageHeight * imageRatio);
	} else {
		// horizontal
		imageWidth = biggerPart;
		imageHeight = (int)(imageWidth / imageRatio);
	}
	LOG.info("New height = " + imageHeight + " and width = " + imageWidth);

	// draw original image to new image object and
	// scale it to the new size on-the-fly
	BufferedImage newImage = new BufferedImage(imageWidth,
			imageHeight, BufferedImage.TYPE_INT_RGB);
	Graphics2D graphics2D = newImage.createGraphics();
	graphics2D.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
			RenderingHints.VALUE_INTERPOLATION_BICUBIC);
	graphics2D.drawImage(image, 0, 0, imageWidth, imageHeight, null);

	// Soften
	float softenFactor = 0.09f;
        float[] softenArray = {0, softenFactor, 0, softenFactor, 1-(softenFactor*4), softenFactor, 0, softenFactor, 0};
        Kernel kernel = new Kernel(3, 3, softenArray);
        ConvolveOp cOp = new ConvolveOp(kernel, ConvolveOp.EDGE_NO_OP, null);
        newImage = cOp.filter(newImage, null);		

	// save new image to OUTFILE
	BufferedOutputStream out = new BufferedOutputStream(new
			FileOutputStream(newfilename));
	try {
		JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
		JPEGEncodeParam param = encoder.getDefaultJPEGEncodeParam(newImage);
		quality = Math.max(0, Math.min(quality, 100));
		param.setQuality((float)quality / 100.0f, false);
		encoder.setJPEGEncodeParam(param);
		encoder.encode(newImage);
	}finally {
		out.close();
	}
	LOG.info("Resized file : " + filename + " to " + newfilename);
}

Enjoy!

This command will show you the summarized size of the current folder and it’s subfolders:

du -hs

Enjoy!

This command flushes and updates local DNS cache wihtout rebooting machine:

# ipconfig /flushdns

Enjoy!

If you use a scheme-based Spring configuration file in Mule server like this one:

<?xml version=”1.0″ encoding=”UTF-8″?>
<beans xmlns=”http://www.springframework.org/schema/beans”
xmlns:xsi=”http://www.w3.org/2001/XMLSchema-instance”
xsi:schemaLocation=”http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd”>
<beans>
….
</beans>

you will get an error:

org.xml.sax.SAXParseException: Document root element “beans”, must match DOCTYPE root “null”.

It is required to use a DOCTYPE header of XML and DTD-based definition:

<?xml version=”1.0″ encoding=”UTF-8″?>
<!DOCTYPE beans PUBLIC “-//SPRING//DTD BEAN//EN” “http://www.springframework.org/dtd/spring-beans-2.0.dtd”>
<beans>
…
</beans>

Enjoy!

When I tried to combine PL/SQL with Java sources in Oracle, I had to know the version of JDK. It concerned with X.509 certificate and handling them. It was bot so easy to find out oracle folder and its java home directory in Linux.

Here is a Java Source for getting environment variables of system:

> create or replace and compile java source named "GetProperty" as
public class GetProperty {
   public static String getProperty(String key) {
     return System.getProperty(key);
   }
}

> create or replace function get_java_property (key varchar2) return varchar2 as
   language java name 'GetProperty.getProperty(java.lang.String) return
java.lang.String';

> select get_java_property('java.version') from dual;

That is all!

I noticed just now that there is a difference between these two type names in Oracle - TEST_T and Test_T. Of course, one says they are equal.

No!

In SQL, actualy, there is no difference, but when you are tring to map this types on Java objects there will be an error. When we use JDBC, we have to call our Java classes with the same names.

class Test_T { … }

Enjoy!

Today, I holded a presentation about Java technologies for cheif developers, architects and managers from other departments. They have developments in .Net/C++/Corba/VisualC and other not very fresh technologies. And now they realized a disability of their products to distribute computing and to make them high-performanced. They archived the limits. Now, it is necessary to add load balancing, session and context caching and so on. And I tried to explain J2EE foundations, Web frameworks and another parts of Java world. Also I presented an initial part of enterprise-level software developement and architecture builing - messaging, object caching, transactions anв pool connections … Of course, they didn’t want to rewrite thousands of code, but they wanted to integrate old implementations with new one and to get an easy distributable and scalable system …

And, I liked it! Really, I felt so good… i wanna be a consultant! I don’t want to dig codes and …

Today, I discovered the great power of using Java language in PL/SQL. We have to handle an array of X509 certificate which were saved in CLOBs. And at the middle of project, we found out that it was very unconvinient to work with certificates using perl. What to do? Our back-office are completely implemented in perl, but there is no good way to dump X509.

But what about Java in PL/SQL?!! This solution fitted perfectly…

This is an example of declaring Stored Procedure in Oracle package:

PROCEDURE CERT_INFO
(
cert IN CLOB,
serial OUT VARCHAR,
cn OUT VARCHAR,
issuer VARCHAR,
public_key OUT VARCHAR,
f_rom OUT DATE, t_o OUT DATE
)
as
language java
name ‘CertInfo.getInfo(java.sql.CLOB, java.lang.String[], java.lang.String[], java.lang.String[], java.lang.String[], java.sql.Timestamp[], java.sql.Timestamp[])’;

And here is a Java Source definition:

create or replace and compile java source named "CertInfo"
as

// imports
import java.security.cert.CertificateFactory;
import java.security.cert.X509Certificate;
import java.sql.Timestamp;
// oracle
import oracle.sql.CLOB;
/**
 * This class implements functions for gathering information about X509 certificate.
 */
public class CertInfo {

	public static void getInfo(CLOB cert, String[] serial, String[] cn, String[] issuer,
			String[] public_key, Timestamp[] f_rom, Timestamp[] t_o) {
		// check input
		if(cert != null) {
			// try to open certificate
			X509Certificate certificate = null;
			try {
...
}

And that is all! But don’t forget about output parameters. As one knows, Java has no pointers and, using array is only way to get values from Java methods.

Enjoy!

Found perfect library for handling command line inputs - Jargs. It is old and abandoned project, but it really works…

The most convinient way to keep X509 certificates is PEM format. ANd, of cource, it is necessary to handle them… showing of issuers, dates and so on. I found the package - Crypt-OpenSSL-X509. But I could only work with 0.3.1. The other versions I was able to install. The Crypt-OpenSSL-X509 is just a bridge between OpenSSL and Perl.

This is an example of getting information from X509 certificate in PEM format:

use Crypt::OpenSSL::X509;

print $x509->pubkey();
print $x509->subject();
print $x509->issuer();
print $x509->email();
print $x509->hash();
print $x509->notBefore();
print $x509->notAfter();

Enjoy!