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MVC
This lecture covers the MVC design pattern for web applications in the context of a mini-project. This includes writing servlets to control and dispatch, models to model the data and the business rules, and JSP pages to author the view.
Outline
- The controller must control and dispatch by relying on the Model and forwarding to a JSP
- Tomcat provides three
Map<String,Object>
places to hold data with three levels of scope: request, session, and application. - State can be captured using the session object. Its API allows us to detect the start of new sessions.
- The model is best packaged as a Java package.
- The model uses beans and POJOs. It is compiled (using
javac
) and tested outside Tomcat. - The servlet's
init
method is responsible for instantiating the model and storing it in the application scope. - Jasper translates a JSP page to a servlet upon receiving the first reference to it (typically from a servlet forward).
- Jasper allows us to embed three things in the JSP page in addition to template (e.g. HTML) code: Expression Language EL, Directives, and Actions. These will be evaluated by Jasper and their values are served as part of the response.
- EL uses a number of built-in, implicit objects.
- Actions are either standard (JSTL) or custom.
To Do
- Read the rest of Chapter 6.
- Read Chapter 8 up to Section 8.4.1 but omit 8.3.2-8.3.3.
- Look at
ELdemo.jspx
andJSTLdemo.jspx
in the Resource Directory. - Do Lab-4.
jsp.1224602887.txt.gz · Last modified: 2008/10/21 15:28 by roumani