I like the concept of MVC, and Spring provides one, called Spring MVC. However it looks like it targets on web application.
If I want to use MVC concept in Spring environment, how to do that?
MVC has nothing to do with Spring; it is a software design architecture/design pattern that you can apply to separate out disparate parts of a software codebase (Model, View and Controller). So long as you implement all your business logic in your model, your GUI logic in your view and your controller responds to any events occuring on your view and updating the view as necessary based on the model then you're adhering to the MVC pattern.
This article shows how MVC would be implemented in a Swing environment. Spring MVC can only ever be used as a web framework. The Spring Framework itself however can still be used wherever you want as it is not tied to a Servlet-based architecture (IoC container).
Once you get to grips with MVC another design pattern/architecture, which is closely related to MVC called MVP (Model View Presenter) is interesting, although very similar, seems to me to be a valid successor to MVC as it completely dumbs down the GUI side.
It is a bit more high level, but you may want to look at Spring RCP project.
Related
Struts, Spring and a few other frameworks implement the MVC architecture to separate the representation of information from the user's interaction with it.
Can any one explain or give me a link for that in Java EE?
Without using a framework, how can I create an MVC application and what are the design patterns needed for that?
Take a look at this presentation, which is part of Beginning & Intermediate Servlet & JSP Tutorials on http://www.coreservlets.com/
you can use Servlet and Jsp to create a MVC application without using any framework,
here are some useful links,
http://forum.codecall.net/topic/72183-mvc-application-in-java/
another useful example,
http://css.dzone.com/articles/web-mvc-java
I think this is a good tutorial on Creating MVC architecture with servlets and jsp
The main concern in creating MVC architecture is the separation of concerns. You need to separate business layer, presentation layer and controler layer
Model layer is achieved by simple POJO
View layer i.e. Presentation layer can be achieved by JSP
Controllers can be achieved by servlets in java ee
MVC stands for Model View and Controller. It is a design pattern that separates the business logic, presentation logic and data.
Controller acts as an interface between View and Model. Controller intercepts all the requests.
Model represents the state of the application i.e. data.
View represents the presentaion.
This link contains an example to implement it with JSP and Servelet.
You can use Servlets and JSP directly.
For managing Java EE applications we are using design patterns.
MVC-1 and MVC-2 are design patterns for managing the UI layer.
Struts and Spring-MVC are implementations of the MVC-2 design pattern.
To answer you first question: the part of the Java EE framework that implements MVC is called JSF. This provides templates, graphical components (widgets) and much more.
To answer your second question: you don't really build an MVC app without any framework. You may be using Servlets and JSP, but that too is a framework. Java EE in its entirety is a (full stack) framework as well.
As for the third question: this is simple, the design pattern to use for MVC is MVC.
So, yeah, this is what I understood.
Servlet is just an intermediary responsible for finding out what the parameters in the request mean. These parameters are given to the .java file. It is a mere intermediary
.java file is the Model which does business logic
View is the JSP that will do the presentation
Did I get that right?
The Model View Controller pattern is not specific to Java or Servlet technology. There are many non-java MVC implementations, and in Java, there are non-Servlet implementations (Swing is an example).
In Java, when using Servlet-based MVC, usually an MVC framework is used. There are two main categories here: action based and component based, the difference being that action based frameworks listen each registered URL independently while component based frameworks keep a component tree and maintain server-side state.
Action based frameworks are Spring MVC, Struts 1+2, Stripes, Play etc. Component based frameworks are Wicket, JSF 1 & 2, Tapestry etc.
Your diagram gets close to the truth, but there are a few subtle misconceptions.
First, it doesn't make sense to speak of .java files. Java source files are totally irrelevant to a deployed web application, it uses compiled .class files only, and the JavaVM can be programmed in many different languages, so the application doesn't care whether the .class files were compiled from Java, Scala, Groovy, JRuby, Clojure, AspectJ or anything else as long as they comply to the Java Class File specification.
Second, while JSP has long been the default view technology in Java Servlet technology, it's far from the only one. Other technologies include Facelets, Velocity, Freemarker etc., and there's also nothing to stop you from writing data directly to a request from a controller without a dedicated view technology (although this is usually not advisable).
Basically, what MVC stands for is a system where there is separate code for business logic (the M), the view technology (V) and the Controller that ties things together. In a well-organized MVC architecture, the M part is so well encapsulated that the same business logic can also be executed through other channels (e.g. web services, direct library access etc.). Also, it should be possible to switch view technologies through configuration from the outside without editing the actual controller logic.
I would advise you to read the docs for the Spring MVC framework, it is to my knowledge the most robust (and also easy-to-use) MVC framework out there, and the tooling support is also great (in either InteliJ Idea or the Eclipse-based SpringSource Tool Suite).
When you are talking about MVC, then all three layers should be separated from each other.
In web application :
1: A controller should be responsible handling the user request then filtering & executing the appropriate actions and then forward the generated response to the client.
2: A model consist of your Business logic,beans & Pojo classes. This should deal with you logic ,perform some operation and renders the generated result to some kind of persistent object or DTO's.
3: A view is consist of your GUI, some presentation-logic , it should be separated from your back-end ,ultimately you are showing an encapsulated form of result to your client i.e. what a client actually needed.
There are two types of MVC: MVC1(Push-MVC) and MVC2(Pull-MVC)
Pull-MVC and Push-MVC are better understood with how the view layer is getting data i.e. Model to render. In case of Push-MVC the data( Model) is constructed and given to the view layer by the Controllers by putting it in the scoped variables like request or session. Typical example is Spring MVC and Struts1. Pull-MVC on the other hand puts the model data typically constructed in Controllers are kept in a common place i.e. in actions, which then gets rendered by view layer. Struts2 is a Pull-MVC based architecture, in which all data is stored in Value Stack and retrieved by view layer for rendering.
It's a question about Spring Framework and its architecture. I have read a lot about Spring in the middle-tier or in the layer scheme. But, I need to know which is the role of this framework inside the MVC pattern.
I must clarify I'm not talking about Spring MVC, but about the entire framework.
For example:
View: JSP, JSF, etc...
Controller: Servlets, Spring?, etc...
Model: Spring?, Hibernate, JPA, etc...
I don´t know where can I locate this framework.
If you use Spring Framework (context, core, aop, tx, jdbc) for inversion of control, transactions, aspect oriented programming, JDBC support you definitely use it in M.
If you use Spring MVC for your web controllers you definitely use it in C.
If you use Spring jsp tags, you also use it in your V.
Below url would be helpful to you.
http://www.tutorialspoint.com/spring/spring_overview.htm
For example, we have the next bunch: Struts, Spring, Hibernate. Can you help me understand the role played by each of the elements?
I know that Hibernate is responsible for all on the database.
But, what role Struts and Spring in this case?
Thanks.
Struts is web application framework - used to give you the possibility to expose your application through web interface without dealing with low level classes. When using struts you should be careful as there often bad advices on using you application logic inside struts classes. Don't do this, struts is just web front-end.
Spring is general application framework that in first place helps you decouple classes from one another using dependency injection. But this is not the only reason for using spring, it provides tons of other features: http security, aspect oriented programming, out-of-the-box integrations and support of different frameworks. So this gives you a fast start on using different technologies.
Hibernate is object relational mapping. Using it you map your classes to database relations and avoid working with SQL requests.
My guess:
Struts is used for presentation purposes. Spring is used for AOP, and Depency Injection. Hibernate is obvious: persistence.
Spring:
Dependancy injection
Transaction Management.
Open Session in View Filters
Spring Security.
or in other words nice clue to between application layers.
Struts:
Model and view Design pattern.
Simplifies web flow.
Struts is for webapplication preparation. It has great form validation f/w, and tiles f/w to create webapplication in a great way.
Spring has 6 modules. It provides abstraction on the java-j2ee application. Spring MVC provides abstraction for struts.
I am using MVC design pattern in jsp-servlet web application, and want to what is the exact difference between MVC1 and MVC2 , can someone help?
EDIT newly I hear that there is 2 versions of using MVC in servlet programming, I hear that in MVC1 there is kind of coupling between controller and view , but in MVC2 they overtake it, if someone know whether this is right or wrong I'll be very thankful.
It might be possible that you read this version in connection with asp.net MVC, as there different versions of that framework. There is no version 2.0 of the mvc pattern, just a version 2.0 of the asp.net MVC framework.
In context of jsp servlets see: Model 1 and Model 2. In a nutshell: Model 1 doesn't have a controller to dispatch requests, Model 2 does.
In MVC 1, controller and model,both are JSP. While in MVC2 controller is servlet and model is java class.
In MVC1 there is tight coupling between page and model as data access is usually done using Custom tag or through java bean call.
In MVC2 architecture there is only one controller which receives all the request for the application and is responsible for taking appropriate action in response to each request.
MVC1 was a first generation approach that used JSP pages and the JavaBeans component architecture to implement the MVC architecture for the Web. HTTP requests are sent to a JSP page that implements Controller logic and calls out to the Model for data to update the View. This approach combines Controller and View functionality within a JSP page and therefore breaks the MVC paradigm. MVC1 is appropriate for simple development and prototyping. It is not, however, recommended for serious development.
MVC2 is a term invented by Sun to describe an MVC architecture for Web-based applications in which HTTP requests are passed from the client to a Controller servlet which updates the Model and then invokes the appropriate View renderer-for example, JSP technology, which in turn renders the View from the updated Model.
The hallmark of the MVC2 approach is the separation of Controller code from
content. (Implementations of presentation frameworks such as Struts, adhere to the MVC2 approach).
That's what I found here: http://www.theserverside.com/discussions/thread.tss?thread_id=20685
MVC-1 Architecture
1) In MVC-1 Architecture, single web component(Servlet/JSP) is used as Controller and view but for other layers separate web components are taken....
2) Since, single component is taken as Controller and view, logics are mixed up..
MVC-2 Architecture
1) In MVC-2 Architecture separate components should be taken for separate layers...
2) Logics are not mixed, there is clean separation between the logics....