JSP Thanks to http courses coreservlets com CourseMaterialscsajsp

JSP Thanks to http: //courses. coreservlets. com/ Course-Materials/csajsp 2. html

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Servlets pros and cons

JSP - The idea

JSP advantages

JSP Lifecycle Server Web Pagina JSP Browser Servlet generato Servlet compilato

JSP - MISCONCEPTIONS

What happens when?

Event table

JSP nuts and bolts • • Syntactic elements: <%@ directives %> <%! declarations %> <% scriptlets %> <%= expressions %> <jsp: actions/> <%-- Comment --%> Implicit Objects: • request • response • page. Context • session • application • out • config • page

JSP nuts and bolts • Syntactic elements: • <%@ directives %> Interaction with the CONTAINER • <%! declarations %> In the initialization of the JSP • <% scriptlets %> In the service method • <%= expressions %> In the service method • <jsp: actions/> •

Two sintaxes - why?

xml syntax for HTML 4 files

XML syntax for XHTML files

JSP expressions

How is it translated?

Example

Predefined variables

Example

Scope of the predefined variables

Scriptlets

How gets is translated?

Example

A scriptlet does NOT need to be a complete Java expression

JSP declarations

How gets it translated? 1

How gets it translated - 2

Example

jsp. Init - jsp. Destroy

Let's recap…

import page directive

content. Type -page. Encoding

Session

Error page

is. Error. Page

is. Thread. Safe Don't you be lazy….

What's wrong here?

Should you use "is. Thread. Safe" ?

@include

jsp: include

jsp: include vs @ include

Augmenting request params

Static pages To let Tomcat serve static pages, we must define a “Web Application”. That is, in the Tomcat Document Root (by default $CATALINA_HOME/webapps/) we must create a folder named after our Web Application (e. g. my. App). webapps my. App In that “my. App” folder, we MUST create a WEB-INF folder (that can be empy). WEB-INF In the my. App folder we can then depost the static html files. On our Tomcat server, the URL for the hello. html file becomes: web. xml http: //machine/port/my. App/hello. html To actually see the webapp, we might have to restart Tomcat hello. html

JSP pages To let Tomcat serve JSP pages, we follow the same procedure that we described for static pages. webapps In the my. App folder we can depost the JSP files. On our Tomcat server, the URL for the hello. jsp file becomes: http: //machine/port/my. App/hello. jsp my. App The WEB-INF directory is still empty. To actually see the webapp, you might have to restart Tomcat (depending on the version you have) The same web. xml file as in the static case must be provided. WEB-INF web. xml hello. jsp