Lecture-6(Moving Towards Script Free JSP)

8/3/2019 Lecture-6(Moving Towards Script Free JSP)

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Lecture-6


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Standard Actions JSTL (tag library) Actions

Custom Actions (next Lecture)


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Makes a JavaBeans component available in a page

Gets a property value from a JavaBeans componentand adds it to the response

Set a JavaBeans property value

Includes the response from a servlet or JSP pageduring the request processing phase


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Forwards the processing of a request to servlet or JSP page

Adds a parameter value to a request handed off to anotherservlet or JSP page using or


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...


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JSP is Easy

JSP is as easy as ...1 + 2 + 3 =

Built on custom tag infrastructure


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Library features Recommended prefix

Core (control flow,

URLs, variable access)

c

Text formatting fmt

XML manipulation x

Database access sql


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Iteration

var convention and variable access paging


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Conditional evaluation

a equals b

Mutually exclusiveconditionals

a equals b

a equals cI dont know whataequals.


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URL retrieval

Data exposed as String or Reader All core URLs supported (HTTP, FTP, HTTPS with JSSE)

Local, cross-context imports supported


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Formatting and parsing

Numbers

Dates

Internationalization

Message bundles

Locale support

Message argument substitution

Hi {0}. I would like to {1} your money today. I will use it tobuy myself a big {2}.


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Use of XSLT, XPath to access, display piecesof XML documents

Example later
http://www.cnn.com/cnn.rsshttp://www.cnn.com/cnn.rss


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Tags for Queries

Updates / inserts Transactions

DataSource-based connection management


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Limitations of MVC , ,

clumsy scripting & expression elements to do morecomplicated Java things

With Expression Language ${expression}

Short and readable and fluid, like JavaScript


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Simple & Concise Flexible (use in conjunction with tag libraries

& custom tags) Robust against Error


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${1.2 + 2.3} => 3.5 ${3/0} => Infinity

\${1} => ${1} ${10 mod 4} => 2


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${4.0 >= 3} => true ${4.0 ge 3} => true Not in Java

${100.0 == 100} => true ${(10*10) ne 100} => false Not in Java ${'hip' > 'hit'} => false Not in Java ${'a' < 'b'} => true Not in Java


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${param.foo} => booyah ${param["foo"]} => booyah \${param["foo"]} => ${param["foo"]} ${header["host"]} => localhost:8080 ${header["accept"]} => */* ${header["user-agent"]} => Mozilla/5.0

(Macintosh; U; PPC Mac OS X; en-us)AppleWebKit/124 (KHTML, like Gecko) Safari/125


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package coreservlets;

public class Salesbean {private double q1, q2, q3, q4;

public SalesBean(double q1Sales, double q2Sales, double q3Sales, doubleq4Sales) {...

}

public double getQ1() {return(q1);}

public double getQ2() {return(q2);}...

}}


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package coreservlets;import java.io.*;import javax.servlet.*;import javax.servlet.http.*;

public class Conditionals extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

SalesBean apples = new SalesBean(150.25, -75.25, 22.25, -33.57);SalesBean oranges = new SalesBean(-220.25, -49.57, 138.25, 12.25);

request.setAttribute("apples", apples);

request.setattribute("oranges", oranges);RequestDispatcher dispatcher =request.getRequestDispatcher("/el/conditionals.jsp");

dispatcher.forward(request, response);}

}


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package coreservlets;import java.io.*;import javax.servlet.*;import javax.servlet.http.*;

public class Conditionals extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

SalesBean apples = new SalesBean(150.25, -75.25, 22.25, -33.57);SalesBean oranges = new SalesBean(-220.25, -49.57, 138.25, 12.25);

request.setAttribute("apples", apples);

request.setattribute("oranges", oranges);RequestDispatcher dispatcher =request.getRequestDispatcher("/el/conditionals.jsp");

dispatcher.forward(request, response);}

}


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Lecture-6(Moving Towards Script Free JSP)

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