How to Use Java Functions In EL

To use a Java Functions in  EL we need three things.

1. The java class with a static method.
2. A Tag Library Descriptor (TLD) File
3. Taglib directive in the jsp page.
4. EL to invoke the function.
   

The java class: In this class the functions declared must be public and static. It should have a non- void type return type. After all, its all the matter of calling method from a jsp page. Put this java file in the /WEB-INF/classes folder. After all this class is not for everyone to see.

The TLD file: TLD provides a mapping between the java class that contains the function and the jsp which will call the function from the java class.

The taglib directive: This directive uses the TLD.

EL to invoke a function: We can call the function by using ${prefix:name()}. This name() we have defined in the <name> tag inside the <function> tag.

The code of the program is given below:

package TLD;

public class Add{
	static int a = 10;
	static int b= 10;
	public static int add(){
		return (a+b);
	}
	public static int playRandom(){
		return (int) ((Math.random()*10)+1);
	}
}

The output of the program is given below:

Download this example.