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Appendix A

Servlet and JSP Quick Reference

Optionally Including the Tag Body

  Tag handler: 

Return 

EVAL_BODY_INCLUDE

 or 

SKIP_BODY

 at different times, 

depending on value of request time parameter.

Manipulating the Tag Body

  Tag handler: 

You should extend 

BodyTagSupport

, implement 

doAfterBody

. Call 

getBodyContent

 to get 

BodyContent

 object describing tag body. 

BodyContent

 has three key methods: 

getEnclosingWriter

, 

getReader

, and 

getString

. Return 

SKIP_BODY

 from 

doAfterBody

.

Including or Manipulating the Tag Body 

Multiple Times

  Tag handler: 

To process body again, return 

EVAL_BODY_TAG

 from 

doAfterBody

. To 

finish, return 

SKIP_BODY

.

Using Nested Tags

  Tag handler: 

Nested tags can use 

findAncestorWithClass

 to find the tag in which 

they are nested. Place data in field of enclosing tag.

  Tag Library Descriptor: 

Declare all tags separately, regardless of nesting structure in real page.

A.15 Integrating Servlets and JSP

Big Picture

  Servlet handles initial request, reads parameters, cookies, session 

information, etc.

  Servlet then does whatever computations and database lookups are 

needed.

  Servlet then stores data in beans.

  Servlet forwards request to one of many possible JSP pages to present 

final result.

  JSP page extracts needed values from beans.

Second edition of this book: www.coreservlets.com; Sequel: www.moreservlets.com.

Servlet and JSP training courses by book's author: courses.coreservlets.com.