My current framework of choice is Struts 2. I have a lot of respect for this framework, and I feel like it does a lot for me in a really elegant way. You will probably hear me blather on about it quite a bit, as it is where I spend most of my time these days.
Struts 2 is an MVC framework, or a Model-View-Controller. MVC is a design pattern that is used to separate the parts of a web application into separate layers. A layer is an isolation of a type of code that keeps it independent of the implementation of the other layers.
The View is the part of the code that actually handles how the data is presented. In Struts 2, this is typically handled by jsp files.
The Controller is what hooks up the View with the Model. It is what controls where the flow goes, what view to display, what business logic to execute. It is kind of the brain of the operation. In Struts 2, the Action class acts as the Controller. Your Action class should not have any business logic in it directly. Rather, it should call into a Service layer that executes your business logic, then alter the flow of the View based off of what it returns.
The Model is the parts of the code that actually contain the business logic. I typically isolate this into a Service layer, which is called from the Action class.
The beauty of the MVC design pattern is that these layers are totally isolated from one another. If we want to start using freemarker templates instead of jsps, we could do that, and we wouldn't have to touch our Action class or Service layer. If we want to change our business logic, it should not affect our Action class or View layer.
There are other MVC frameworks out there. What makes Struts 2 stand out from the others? Well, to start with, it is the one that my employer wants me to use - always a good incentive. That being said, I personally still prefer Struts 2 to any of the other frameworks I have tried. My only other experience has been with Spring MVC, which seems to be a good solution as well, but made less sense to me than Struts 2 does.
Struts 2 has a lot of features, and I have barely begun to scratch the surface on all that it can do. More posts will come in the future that start talking about the Interceptor concept, the built in validation framework, and many of the other features that Struts 2 has to offer.
I leave you today with the thing that most developers always want to see in a new technology - the Hello World.
The following clips were taken from http://struts.apache.org/2.x/docs/hello-world.html.
The Action class:
package tutorial;
import com.opensymphony.xwork2.ActionSupport;
public class HelloWorld extends ActionSupport {
public static final String MESSAGE = "Struts is up and running ...";
public String execute() throws Exception {
setMessage(MESSAGE);
return SUCCESS;
}
private String message;
public void setMessage(String message){
this.message = message;
}
public String getMessage() {
return message;
}
}
The struts.xml file:
<!DOCTYPE struts PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
"http://struts.apache.org/dtds/struts-2.0.dtd">
<struts>
<package name="tutorial" extends="struts-default">
<action name="HelloWorld" class="tutorial.HelloWorld">
<result>/HelloWorld.jsp</result>
</action>
<!-- Add your actions here -->
</package>
</struts>
The JSP file:
<%@ taglib prefix="s" uri="/struts-tags" %>
<html>
<head>
<title>Hello World!</title>
</head>
<body>
<h2><s:property value="message" /></h2>
</body>
</html>
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