How can I know if a Java app uses the MVC design pattern? For example I want to know if this app from github uses the MVC design pattern: https://github.com/eveningstar33/GoalTracker
It is a fullstack app, the frontend is made in Angular and the backend is made in Spring Boot. And if yes I want to know who is the Model? I think that RestController is the Controller and the Angular app is the View. Isn't it? Or if an app uses Spring MVC does it also use MVC design pattern?
MVC part in Spring MVC stays for implementation (very good implementation :)) of broader JSP/Sevlets based MVC concept, where typically we have Front Controller Servlet, which dispatches requests to corresponding View Controllers and resolve/prepare result views to be rendered for user.
The MVC parts could change when we have both Angular (or any other Single Page Application JS framework) and Spring MVC working together. As in Angular usually you have "Controller" class per each component, which can have a lot of logic inside, connecting to different services. So less logic stays on server and it acts as a proxy to DAO layer to perform CRUD operations. For such cases it is quite common to see:
View - Angular View templates (e.g. Goal View)
Controller - Angular Controllers (e.g. Goal Component)
Model - REST API (built with or without Spring MVC framework) (e.g. Goal Resource)
MVC is one of the design patterns in software development. Model is usually a POJO (Plain Java Object) that encapsulates the data of the business objects, View is the one that users interact with that is also responsible to take request from users and render response and Controller sits in between View and Model to transfer data as well as act as a navigation decision maker.
You can write the back end in Spring Boot providing HTTP APIs to any client including Angular. Angular internally uses TypeScript ( a super set of JavaScript ) that you can use to just consume the APIs.
Here is one such example, where I have written written services in Sprint Boot - https://github.com/royalghost/PortfolioTrackerServices
And then there is a separate project that consumes the above services using Angular - https://github.com/royalghost/PortfolioServicesTrackerClient
Spring MVC is one of the framework that implements the MVC design patterns. You can take a look at a separate project that uses Spring MVC - https://github.com/royalghost/UserRegistration . Also note that this project uses Spring Boot since Spring Boot is just an easy way to put all the required libraries together to quickly build, start and deploy an application.
Angular is more popular with Single Page Application ( SPA ) and a lot of server side computation is now pushed towards client ( this is also to scale the product. ) Therefore, it is completely up to the developer on which design patterns or architecture to choose when using the same technology and stacks.
References:
MVC - https://en.wikipedia.org/wiki/Model%E2%80%93view%E2%80%93controller
Angular - https://angular.io/guide/architecture
Related
I have built a web app using Spring 4. The app allows search users, create elements and so on.
The requirements changed. Now I have to deliver search results as json instead of html (but keep html just in case).
The question is, should I use controllers and redirect to a jsp with json/html according a parameter? or use Spring restful web service?(I've never used this and need to learn how to) if I use Spring restful do I have to do the same job I've already did with the web version to generate json?
It depends on how did you design your previous MVC application.
My suggestion is follow:
But better to use Spring REST Controller. Mechanism is more or less same like MVC. I assume you have service layer for CRUD data of your application.
Better to use those Service and Repository and just create #RestController for your application. #ResponseBody should be your models which are you returning from controller. And #RequestBody will hold the data for generaly POST, PATCH, DELETE requests.
Good luck.
Let me start by saying I was just thrown into a Spring MVC project and my only experience has been from a GWT project.
In GWT we created a hierarchy of pages filled with 'presenters' which indicated a new page. So if I wanted to create a new page I could simply create a new presenter and widget number and that number was inserted into the URL, thus creating a new web page. From there I could assign text boxes, tables, etc to that widget number, which in turn would populate my new page.
Questions
In a Spring MVC hibernate project how would I indicate I want a new page? where would information for this page be contained? Much of the Java files I see in my project are validators and logic oriented and less page structure and layout.
I used click listeners and handlers a lot in GWT. Why have I been unable to find any in my project's existing code base? How is this type of thing handled in Spring?
1) MVC means model-view-controller pattern, so you need to learn how to integrate your views (html, jsp, jstl) into Spring. Refer here:
http://docs.spring.io/spring/docs/2.0.8/reference/view.html
2) There are also listeners in Spring, for example, ContextLoaderListener.
These might help:
http://www.docbyte.com/fr/blog/integrating-gwt-with-spring-and-hibernate
http://www.javacodegeeks.com/2010/05/gwt-2-spring-3-jpa-2-hibernate-35-2.html
A Spring MVC application is a web application built on top of the Servlet API. You run such an application in a Servlet container which acts as an HTTP server.
Spring MVC follows the Model-View-Controller architectural style. A controller is dispatched to handle the request based on the mappings you configure. The controller performs some logic, delegates to the model, prepares it and makes it available to the view. The view can be pretty much anything. You can have it have it generate HTML, XML, JSON, some other binary content type, etc. That content is written to the HTTP response which your HTTP client can then display/render/download.
In a typical Spring MVC app, you'll have the views setup with JSPs. Your configuration will declare an InternalResourceViewResolver which will forward to JSPs based on view names that the controller handler methods (methods annotated with #RequestMapping) return.
GWT follows a completely different methodology than Spring MVC. Spring MVC is straight up client/server. The client sends a request. Spring MVC receives it, dispatches a controller, and returns a response. The lines are clear. In GWT, not so much. IMO it feels more like a standalone application with buttons and listeners. The actual underlying implementation is still client/server, it's simply hidden from you as a developer.
When you click the button on a form, a browser typically sends an HTTP request to the server, the server responds and the browser renders some other page (or does something else, depending). In Spring, the flow is as described above. The web app receives the request, dispatches to a controller which returns a view, and then returns a response based on that view. As a developer, you code most of that.
I am new to spring world. I am trying to add to new functionality to an existing spring MVC based reporting project. The new functionality would give the user an ability to schedule a particular report to run every so often.
I see that in current design, model and Controller sections of MVC is tightly coupled. Due to time constraints, I am not trying to separate Model and Controller instead want to use the existing infrastructure as is. My plan is to mimic the browsers request in a pojo and somehow call spring's MVC to handle my request. Am i going in right direction, if so how to I invoke the spring MVC from a POJO, if not, what would be the right approach. Please help........
If i understand you correctly, basically you would like to :
create a non-web application that makes requests to existing Spring MVC controllers
and that you have to reuse existing controllers
and NOT reusing the business model, because you dont have the time to separate the business model from the controller
Basically you are doing web services with this approach, where you make requests to the controllers via http using a http client library. And perhaps, get the response as json, which you can later map into a java bean, and continue your work from there.
You can have the controller to return the view's model as xml, or json, etc, or even directly return a bean as json or xml using spring's message converter.
If you are already using Spring 3, there is a RestTemplate that you can make use of to simplify this.
You could also make use of Apache's HttpClient, whose interesting example that you can see in this REST template code.
This related Q&A on java http clients could also be helpful.
I am new to Spring MVC3 framework in java but I am familiar with java coding.
I want to write two application using this framework.
First application recieves requests through a SOAP web services and sends response in form of SOAP XML Object.
Second application have a simple servlet to recieve request and send responces.
I have studied Java MVC3 framework. It requires view to be called who are mapped against which controller will handles its request. But,
How I can do this using a webservice, so that when a specific method using SOAP services is called, I can forward that request to its relevant servlet and sends response back as a SOAP xml file.
How can I do this for my second application as well that recieves request through a servlet.
I hope all this make sense.
regards,
Aqif
If you want to stick with Spring, you can use Spring Web Services for application 1. Application 2 would be a more traditonal Spring Web app (uses a servlet, but framework does not require you to work in the servlet...instead you will work in more fine grained components).
If you dont want to stick with Spring for the web services, you can always use something like Apache Axis
The usual structure is as follows:
you have spring-mvc controllers to handle your browser requests
you have other components that handle the SOAP requests
both of the above invoke the same underlying services which serve them with the data that is to be sent to the user. The data is in java objects, which are later transformed to whatever is required
For the 2nd point you can pick some JAX-WS implementation, like CXF (it has nice spring support as well)
Spring Web Services specifically supports a Spring MVC-like model for responding to SOAP calls, as you describe.
the second one is Spring MVC directly. Heck, it sounds like - though I can't be sure without more information - that you're trying to build RESTful web services. There, too, Spring MVC is the right choice.
Evening all :)
I'm looking to create a Java web application. I envisage that it will use Spring web MVC and JSPs, however I would like to expose certain functionality as REST calls so I can create an android client.
Does spring offer anything to help me in this area? How can I keep the REST code and the web front end code separate yet not have to maintain essentially 2 versions of my application (one for the web, one for REST clients).
Not looking for spoon feeding, just some pointers of where I should start reading.
As others have mentioned, Spring has pretty good in-built REST support now. When combined with annotations, this allows really simple set-up of a RESTful API. Spring can be configured with different view resolvers, which can automatically respond with a different view of the data depending on the Accept header for example. So you could return either JSON or JSP automatically from the same data, see the ContentNegotiatingViewResolver. Your Controller and Model can then be common and implemented once, leaving the work in the View layer.
I've used this approach before to return JSON when the request was via AJAX and a JSP view built with the same data when accessed by a browser.
Jersey is a pretty nifty tool. It integrates well with tools like Spring, Guice, and Jackson to provide you a pretty seamless way to create RESTful resources.
Jersey is pretty simple, works well, and serves as the reference implementation to boot. Plus, it has some nice REST client support, much of which will probably make it into the JAX-RS spec.
In terms of marrying that with Spring MVC, I'd recommend you make sure you model your application so that you have facades (Service classes) that provide all the core functionality you need and then simply reference them as needed in your MVC code or REST code. You shouldn't be duplicating business logic
You can do this using Spring 3.0. Spring 3.0 came out with the ability to specify #PathVariables to pull values out of the URL path (previously this was not easy in Spring MVC).
You would also use #RequestMapping to specify the HTTP method(s) each method in your controller should respond to.
I've also use Spring Security to implement an API key type of functionality. This way you can restrict access to your API in a way that is easy for REST clients to implement. I had to extend org.springframework.web.filter.GenericFilterBean and add a the proper Authentication like this
SecurityContextHolder.getContext().setAuthentication(apiKeyAuth)
There's a new REST API in Spring 3.0 MVC:
http://blog.springsource.com/2009/03/08/rest-in-spring-3-mvc/
http://www.springsource.org/download
Apache CXF integrates well with Spring and offers many method for exposing services. From the overview section of the CXF homepage:
CXF helps you build and develop
services using frontend programming
APIs, like JAX-WS and JAX-RS. These
services can speak a variety of
protocols such as SOAP, XML/HTTP,
RESTful HTTP, or CORBA and work over a
variety of transports such as HTTP,
JMS or JBI.