meljun cortes developing jsp

8/11/2019 MELJUN CORTES Developing JSP

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JSP TechnologyJavaServer Pages (JSP) enable youto write standard HTML pagescontaining tags that run powerfulprograms based on the Javaprogramming language.

JSP is capable of returning staticand dynamic content.

It allows separation of presentationand business logic.

MELJUN ORTES


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Hello Servlet Code

public void generateResponse(HttpServletRequestrequest,HttpServletResponse response) throwsIOException {

// Determine the specified name (or usedefault) String name =request.getParameter("name"); if ( (name == null) || (name.length() ==0)) { name = DEFAULTJSTAME;

// Specify the content type is HTMLresponse.setContentType("text/html");PrintWriter out = response.getWriter();

// Generate the HTML responseout.printIn("");out.println("");out.println("Hello Servlet");out.println("");out.println("");out.printIn("Hello, " + name + "");out.printIn("");out.println("");out.close();


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JSP Lifecycle Phases

Translation phase

Compile phase

Execution phase


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JSP Scripting ElementsJSP scripting elements areembedded with the tags andare processed by the JSP engineduring translation of the JSP page.


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JSP Scripting ElementsThere are five types of scriptingelements:

1. Comments 2. Directive tag 3. Declaration tag 4. Scriptlet tag 5. Expression tag


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CommentsDocumentation is important to anyapplication. There are two types ofcomments permitted in a JSP page:

HTML comments

JSP page comments


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CommentsJava comments can be embeddedwith scriptlet and declaration tags.

/* This is a Java comment. It willshow up in the servlet code. It willnot show up in the response. */


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Directive TagA directive tag provides informationthat will affect the overalltranslation of the JSP page.

The syntax for a directive tag is:

Example:


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The page DirectiveThe page directive is used tomodify the overall translation ofthe JSP page.

Page dependent properties of thepage directive:

language attributeextends attributeimport attribute

session attributebuffer attributeautoFlush attributeisThreadSafe attribute

info attributeerrorPage attributeisErrorPage attributecontent T e attribute


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Declaration TagA declaration tag allows you toinclude members in the JSP servletclass, either attributes or methods.

The syntax for a declaration tag is:

Example:


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Declaration TagYou can use a declaration tag tooverride the jsplnit() andjspDestroy() life cycle methods.

The signature of these methods hasno arguments and returns void .

Example:


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Scriplet TagA scriptlet tag allows the JSP pagedeveloper to include arbitrary Javatechnology code in the

_jspService() method.

The syntax for a scriplet tag is:

Example:

10 ) { %>

I is a big number.

I is a small number


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Scriptlet with Loop

...


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Expression TagAn expression tag holds a Javalanguage expression that isevaluated during an HTTP request.The result of the expression isincluded in the HTTP responsestream.

The syntax for a expression tag is:

Example:

Ten is

Thank you, ,for registering for thesoccer league.

The current day and time is:


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Implicit Variables

Variablename

Description

application The ServletContext object for theWeb application.

config The ServletConfig object associated

with the servlet for the JSP page.pageContext This object encapsulates the

environment of a single request forthis JSP page.

page This variable is equivalent to the thisvariable in the Java programminglanguage.

exception The Throwable object that wasthrown by some other JSP page. Thisvariable is only available in a "JSPerror page."

meljun cortes developing jsp

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