imported>Uzume: Apache Struts

2024-07-17T20:14:52Z

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{{Short description|Programming language and libraries}}
'''Java view technologies and frameworks''' are [[web-based]] [[software libraries]] that provide the [[user interface]], or "[[Model–view–controller|view-layer]]", of [[Java (programming language)|Java]] [[web application]]s. Such [[application framework]]s are used for defining [[web page]]s and handling the [[HTTP]] [[List of HTTP header fields#Requests|requests]] (clicks) generated by those web pages. As a sub-category of [[web framework]]s, view-layer frameworks often overlap to varying degrees with web frameworks that provide other functionality for Java web applications.

Java view-layer frameworks often claim to support some or all of the [[model–view–controller]] design pattern.

==At a glance==
{| class="wikitable"
|-
! Action-based frameworks:
| [[Apache Struts]], [[Spring Framework|Spring MVC]]
|-
! Component-based frameworks:
| [[Apache Click]], [[Apache Tapestry]], [[Apache Wicket]], [[Jakarta Faces]]
|-
! Web template systems:
| [[Apache Tiles]], SiteMesh, [[Thymeleaf]]
|-
|}

* [[Jakarta Faces]] (JSF), [[Apache Tapestry]] and [[Apache Wicket]] are competing component-based technologies, abstracting the [[Stateless protocol|stateless]] HTTP request-response cycle and the [[Jakarta Servlet]] [[API]] behind an [[Object-oriented programming|object-oriented]], event-driven component model.
* In contrast, Struts and the [[Spring Framework|Spring MVC Framework]] are action-oriented frameworks that provide a thinner [[abstraction layer]] over the servlet [[API]].
* Apache Tiles is a templating framework designed to work with Struts.
* [[Facelets]] is a view definition and templating technology designed to work with JSF.
* SiteMesh can be used with any [[Jakarta Server Pages|Jakarta Pages]] (JSP).
* Facelets, Tapestry and Wicket have their own templating approaches based on [[HTML]]/[[XHTML]].
* [[Apache Click]] uses HTML based [[Apache Velocity]] templates and [[plain old Java object]]s (POJOs), with JSP optional.

==Servlet API==
{{main |Jakarta Servlet}}

The Servlet API is the foundation of almost all Java Web View technologies. Servlet provides the basic mechanism for writing Java [[class (computer programming)|class]]es for web applications. Servlets can respond to HTTP requests, create cookies and maintain sessions.

==Jakarta Pages (JSP) ==
{{main |Jakarta Server Pages}}

* Built on top of the Servlet API, JSP provides a document-centric, tag-based templates, server programming model which can generate many forms of textual content.
* Java code may be embedded in JSP files and is compiled and executed when a request is received.

==Apache Struts==
{{main |Apache Struts}}

* Struts provides for a [[coupling (computer programming)|decoupling]] of the Controller and the View.
* Requests are received by a Java Class (Controller) which can decide which View to display.
* The actual View can be written in different view technologies, like JSP, free marker template, velocity template etc.
* An XML [[configuration file]] is used to specify the "Page Navigation", i.e. the flow of the request to the appropriate Controller, and which View to display based on the outcome of the Controller.
* '''Competitor''': Spring MVC, Grails

==Apache Tapestry==
{{main |Apache Tapestry}}

* A component-based view framework.
* Classes are written as POJOs and byte-code transformed at runtime
* Configured with annotations and naming conventions rather than XML
* Compared to JSPs, enforces a clear separation of [[HTML element|HTML markup]] and Java code.
* HTML templates can be directly previewed by web designers
* Changed component classes are live-reloaded into running application for faster development.
* Uses the [[Post/Redirect/Get]] navigation pattern for form submission.
* '''Competitor''': Wicket, JSF

==Apache Tiles==
{{see also |d:Special:EntityPage/Q28912908|l1=Apache Tiles}}

* This is an HTML templating framework based on the [[composite pattern]].
* It allows for the HTML page to be broken up into multiple "pagelets", called Templates, Definitions and Composing pages.
* At [[runtime (program lifecycle phase)|runtime]] the pagelets are stitched together to generate the final HTML. Pages are written in JSP.
* '''Competitor''': SiteMesh

==Apache Wicket==
{{main |Apache Wicket}}

* A component-based view framework.
* Pages directly interact with stateful Java components on the server.
* Components and their state are managed by the Wicket framework, freeing the application developer from having to use HttpSession directly to manage state.
* Does not require XML for configuration.
* Compared to JSPs, enforces a clear separation of [[HTML element|HTML markup]] and Java code.
* Web page components are 'pushed' into the HTML markup from the code.
* '''Competitor''': Tapestry, JSF

==Jakarta Faces and Facelets==
{{main |Jakarta Faces}}

* A specification for component-based view frameworks.
* [[Eclipse Mojarra]] and [[Apache MyFaces]] implementations are available
* Typically uses Facelets for XML/XHTML-based templating.
* Classes are written as POJOs, with Annotations or XML configuration files used to associate them with page and component templates.
* The [[Unified Expression Language]] allows binding component fields and events to POJO bean properties and methods.
* Conversion and validation constraints can be specified in Facelets and are automatically applied, normally resulting in reposting of the same page with error information in case of failure.
* Navigation can be via configuration file rules or directly specified in the page.
* Can transparently support [[Ajax (programming)|Ajax]].
* '''Competitor''': Wicket, Tapestry

==SiteMesh==
{{main |SiteMesh}}

* SiteMesh is an HTML templating framework based on the "Decoration" model.
* It allows for the creation of a 'decoration' template which is then applied to any other HTML to generate a new HTML.
* The newly generated HTML contains elements from the original HTML blended into the template.
* This allows for the original HTML to be very simple and devoid of any formatting or layout specification. The template, in turn, is devoid of any actual information.
* Blending the two allows for a consistent [[look and feel]] for all [[web page]]s.
* '''Competitor''': Tiles

==Spark==
{{main |Spark (software)}}

* Spark a micro web framework built around a simple routing system
* It runs on an embedded [[Jetty (web server)|Jetty]] web server by default, but can be configured to run on other webservers.
* It supports three different templates engines: [[Apache Velocity|Velocity]], [[FreeMarker]] and [[Mustache (template system)|Mustache]]
* It aims to facilitate rapid development, and does not make use of annotations or proprietary solutions.

==See also==
{{Portal|Computer programming}}
* [[List of web service frameworks]]
* [[List of Java frameworks]]

[[Category:Java (programming language)]]
[[Category:Java APIs]]

Java view technologies and frameworks - Revision history

imported>Uzume: Apache Struts