First script with Velocity (VM)

Velocity is a Java-based template engine. It permits web page designers to reference methods defined in Java code. Basically, you can create files (HTML, XML, etc…) writing scripts and generate them following a template.

 

– Create Maven Project.

– Add dependency in your pom file – Change the version of the lib:

<dependency>

  <groupId>org.apache.velocity</groupId>

  <artifactId>velocity</artifactId>

  <version>1.6.4</version>

</dependency>

 


– Create a Vm template, like this one. Save as .vm (I created outside the package test). So, place your template in Project > src > customer.vm and not with the code which the structure is: Project > src > package.test:

Hello $word! This is your first Velocity script !

 

– Create a Java Class called CreateScript:
import java.io.StringWriter;

import org.apache.velocity.app.VelocityEngine;
import org.apache.velocity.exception.MethodInvocationException;
import org.apache.velocity.exception.ParseErrorException;
import org.apache.velocity.exception.ResourceNotFoundException;
import org.apache.velocity.Template;
import org.apache.velocity.VelocityContext;

public class createXml {
   public static void main(String[] args) throws Exception {
   VelocityEngine ve = new VelocityEngine();
   ve.init();

   try {
    Template t = ve.getTemplate("src/helloworld.vm");

    VelocityContext context = new VelocityContext();
    context.put("word", "World");
    StringWriter writer = new StringWriter();
    t.merge(context, writer);
    System.out.println(writer.toString());
    } catch (ResourceNotFoundException rnfe) {
      System.out.println("Couldn't find the template");
    } catch (ParseErrorException pee) {
      System.out.println("syntax error: problem parsing the template");
    } catch (MethodInvocationException mie) {
      System.out.println("something invoked in the template");
      System.out.println("threw an exception");
    } catch (Exception e) {
    }
  }
}

– Vm file is the template, you will create the template and what the variables that will have the value that you want.

– Inside Java Class:

You need initialize the Velocity API – Write the path of the vm template – Initialize the context and write all the variables and the values (name – variable, word – value) – Initialize the Writer which will render the template – Merge the context and the values creating the template – Show the result

– To run the project, first I had to compil with maven test and after this I just choose Run As – Java Application.

So, this is the first script, I will write more about, but between this you can have a look on the links below. See you guys 🙂

 

Sources:

http://velocity.apache.org/engine/devel/developer-guide.html

https://velocity.apache.org/engine/releases/velocity-1.5/webapps.html

http://www.javaranch.com/journal/2004/03/Velocity-AnIntroduction.html

http://www.javaworld.com/article/2075966/core-java/start-up-the-velocity-template-engine.html