Chapter 7: JSP Directives

1
Chapter 7 JSP Directives
Reference Beginning JSP
2
Objectives

• Processing of JSP Directives
• JSP Directives
• Page Directive
• Taglib Directive
• Include Directive

3
Review JSP Directives

• Reference page 32
• Directives
• Gives special instructions to the JSP container
• Not used to generate output directly
• Allowable directives (more details in Chapter 7)
• page directive
• taglib directive
• include directive
• Syntax lt_at_ directive gt
• XML-compatible syntax (without using special
  characters)
• ltjspdirective.taglib /gt

4
Processing of JSP Directives

• Reference Page 215
• Phase 1 Translation
• JSP page converted to Java code
• Phase 2 Compilation
• Java code is compiled into executable byte code.
• The binary byte code is executed when an incoming
  HTTP request arrives at the server

5
Page Directive (1)

• Reference page 217
• language attribute
• lt_at_ page language"java" gt
• import attribute
• lt_at_ page language"java" import
  "com.wrox.begjsp.ch03.,java.util. gt
• contentType attribute
• lt_at_ page language"java" contentType"text/html"
  gt
• errorPage, isErrorPage attribute
• Under ltTomcatgt\webapps\jsp-examples\error
• err.jsp lt_at_ page errorPage"errorpge.jsp" gt
• errorpge.jsp lt_at_ page isErrorPage"true" gt

6
Page Directive (2)

• Other attributes
• session (default true), isELIgnored (default
  false)
• info (for JSP dev tools), extends (not
  recommended)
• XML syntax example
• Example 1 xindex.jsp
• ltjsproot
• xmlnsjsp"http//java.sun.com/JSP/Page"
• version"2.0"gt
• ltjspdirective.page language"java"
  contentType"text/html" /gt
• lthtmlgtlt/htmlgt
• lt/jsprootgt

7
Page Directive Example

• index2.jsp contentType"text/xml
• Result
• JSP container responds with an XML document

8
Taglib Directive

• Reference page 223
• uri attribute
• To locate TLD file that describes the tag library
• lt_at_ taglib prefix"c" uri"http//java.sun.com/jsp
  /jstl/core" gt
• tagdir attribute
• To locate tag files for a tag library
• lt_at_ taglib prefix"wt" tagdir"/WEB-INF/tags/wroxt
  ags" gt
• prefix attribute
• Prefix to be used in the JSP page for referring
  to this tag library
• ltcwhen test"param.pg 'mine'"gtltwtmyPage/gtlt
  /cwhengt

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No Taglib Directive Example

• Using JSP Tags
• without taglib directive
• E.g., index2.jsp
• In web.xml
• ltjsp-property-groupgt
• lturl-patterngt/example2/index2.jsplt/url-patterngt
• ltinclude-preludegt/WEB-INF/jspf/pre1.jspflt/include
  -preludegt
• lt/jsp-property-groupgt
• In pre1.jsp
• lt_at_ taglib prefix"c" uri"http//java.sun.com/jsp
  /jstl/core" gt
• lt_at_ taglib prefix"wt" tagdir"/WEB-INF/tags/wroxt
  ags" gt

10
Include Directive

• Reference page 231
• file attribute
• Mandatory
• Merge content of external files with current JSP
  during translation phase
• lt_at_ include file"news.jsp" gt
• Include directive vs. ltjspincludegt
• Translation time vs. request time
• ltjspincludegt is recommended to overcome
  limitations (e.g., changes to JSP page is
  automatically recompiled)

11
Next Steps

• Try It Out sections of Textbook (Chapter 7)
• Examples 1, 2, 3