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When even JSTL is not enough Head First Servlets and JSP By Bert Bates, Kathy Sierra, Bryan Basham ISBN: 0596005407 Publisher: O'Reilly Prepared for Augusto Jaramillo Forcada, Safari ID: augustojf.cv@gmail.com Print Publication Date: 8/1/2004 User number: 729515 Copyright 2007, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited. FXVWRPWDJGHYHORSPHQW \RXDUHKHUH  3IMPLETAGSARESIMPLEITSALLABOUTDO4AG"UTWITHCLASSICTAGS THERESADO3TART4AGANDADO%ND4AG!NDTHATBRINGSUPAN INTERESTINGPROBLEMWHENANDHOWISTHEBODYEVALUATED4HERES NODO"ODYMETHODBUTTHEREISADO!FTER"ODYMETHODTHATS CALLEDAFTERTHEBODYISEVALUATEDANDBEFORETHEDO%ND4AGRUNS +TI[[QK\IO[PI^MILQNNMZMV\TQNMKaKTM &RQWDLQHU :HE&RQWDLQHU &ODVVLFWDJFODVV 7DJ+DQGOHU2EMHFW These happen the Þ rst time the tag is invoked, but the Container may (depending on the circumstances) reuse the Classic tag object after this. This gives the handler a reference to a PageContext. If the tag is invoked with attributes, the JavaBean-style setter for each attribute is called (just as with SimpleTag handlers). A nested tag can communicate with the other tags in which its nested. doAfterBody() lets you do things AFTER the body runs, and unlike the other methods it can be invoked more than once. The body is evaluated between the doStartTag() and doEndTag() methods.         &ODVVLF+DQGOHUFODVV /RDGFODVV ,QVWDQWLDWHFODVVQRDUJFRQVWUXFWRUUXQV &DOOWKHVHW3DJH&RQWH[W3DJH&RQWH[WPHWKRG ,IWKHWDJKDVDWWULEXWHVFDOODWWULEXWHVHWWHUV &DOOWKHGR6WDUW7DJPHWKRG &DOOWKHGR(QG7DJPHWKRG ,IWKHWDJLVQHVWHGLQYRNHGIURPZLWKLQDQRWKHU WDJFDOOWKHVHW3DUHQW7DJPHWKRG ,IWKHWDJLV127GHFODUHGWRKDYHDQHPSW\ ERG\$1'WKHWDJLV127LQYRNHGZLWKDQHPSW\ ERG\$1'WKHGR6WDUW7DJPHWKRGUHWXUQV (9$/B%2'<B,1&/8'(WKHERG\LVHYDOXDWHG ,IWKHERG\FRQWHQWZDVHYDOXDWHGFDOOWKH GR$IWHU%RG\PHWKRG doEndTag() is always called once, either after doStartTag() or after doAfterBody(). Chapter 10. When even JSTL is not enough Chapter 10. When even JSTL is not enough Head First Servlets and JSP By Bert Bates, Kathy Sierra, Bryan Basham ISBN: 0596005407 Publisher: O'Reilly Prepared for Augusto Jaramillo Forcada, Safari ID: augustojf.cv@gmail.com Print Publication Date: 8/1/2004 User number: 729515 Copyright 2007, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited.  FKDSWHU 4HEDO3TART4AGANDDO%ND4AGMETHODSRETURNANINT4HATINTTELLSTHE #ONTAINERWHATTODONEXT7ITHDO3TART4AGTHEQUESTIONTHE#ONTAINER ASKSISh3HOULD)EVALUATETHEBODYvASSUMINGTHEREISONEANDASSUMING THE4,$DOESNTDECLARETHEBODYASEMPTY 7ITHDO%ND4AGTHE#ONTAINERASKSh3HOULD)KEEPEVALUATINGTHERESTOF THECALLINGPAGEv4HERETURNVALUESAREREPRESENTEDBYCONSTANTSDECLARED INTHE4AGAND)TERATION4AGINTERFACES <PM+TI[[QKTQNMKaKTMLMXMVL[WVZM\]ZV^IT]M[ GR6WDUW7DJ 6.,3B%2'< (9$/B%2'<B,1&/8'( GR(QG7DJ 6.,3B3$*( (9$/B3$*( 3RVVLEOHUHWXUQYDOXHVZKHQ \RXH[WHQG7DJ6XSSRUW GR$IWHU%RG\ 6.,3B%2'< (9$/B%2'<B$*$,1 GR$IWHU%RG\ GR6WDUW7DJ (YDOXDWH%2'< GR(QG7DJ (YDOXDWH3$*( UHWXUQ(9$/B%2'<B,1&/8'( UHWXUQ6.,3B%2'< UHWXUQ6.,3B%2'< UHWXUQ(9$/B%2'<B$*$,1 UHWXUQ(9$/B3$*( 'RQH UHWXUQ6.,3B3$*( This is the only return value constant declared in IterationTag (the others are all from Tag).  :LWKGR6WDUW7DJWKHUHWXUQYDOXHVDUH 6.,3B%2'<DQG(9$/B%2'<B,1&/8'(%XWZLWK GR(QG7DJWKHYDOXHVDUH6.,3B3$*(DQG (9$/B3$*( ,IWKHQDPHVZHUHFRQVLVWHQWGR(QG7DJZRXOGUHWXUQ (9$/B3$*(B,1&/8'(DVRSSRVHGWR(9$/B3$*( WRPDWFKWKHZD\GR6WDUW7DJUHWXUQV(9$/B%2'<B ,1&/8'(%XWLW¶VQRW6RGRQ¶WEHIRROHGLI\RXVHHFRGH RQWKHH[DPZLWKFRUUHFWORRNLQJEXWZURQJUHWXUQYDOXHV 7KHFRQVWDQWVXVHGDVUHWXUQ YDOXHVIRUGR6WDUW7DJDQG GR(QG7DJUHWXUQYDOXHFRQVWDQWV DUHLQFRQVLVWHQWO\QDPHG Returning SKIP_PAGE from doEndTag() is exactly like throwing a SkipPageException from a Simple tag! If a page included the page that invoked the tag, the current (included) page stops processing, but the including page continues &ODVVLFWDJOLIHF\FOH Chapter 10. When even JSTL is not enough Chapter 10. When even JSTL is not enough Head First Servlets and JSP By Bert Bates, Kathy Sierra, Bryan Basham ISBN: 0596005407 Publisher: O'Reilly Prepared for Augusto Jaramillo Forcada, Safari ID: augustojf.cv@gmail.com Print Publication Date: 8/1/2004 User number: 729515 Copyright 2007, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited. FXVWRPWDJGHYHORSPHQW \RXDUHKHUH  7HENYOUWRITEATAGHANDLERTHATEXTENDS4AG3UPPORTYOUGETALLTHELIFECYCLEMETHODSFROMTHE 4AGINTERFACEPLUSTHEONEMETHODFROM)TERATION4AGDO!FTER"ODY7ITHOUTDO!FTER"ODY YOUCANTITERATEOVERTHEBODYBECAUSEDO3TART4AGISTOOEARLYANDDO%ND4AGISTOOLATE "UTWITHDO!FTER"ODYYOURRETURNVALUETELLSTHE#ONTAINERWHETHERITSHOULDREPEATTHEBODY AGAIN%6!,?"/$9?!'!).ORCALLTHEDO%ND4AGMETHOD3+)0?"/$9 1 \ M Z I \ Q W V < I O  T M \ [  a W ]ZMXMI\\PMJWLa 7DJLQWHUIDFH LQWGR(QG7DJ 7DJJHW3DUHQW LQWGR6WDUW7DJ YRLGVHW3DJH&RQWH[W3DJH&RQWH[W YRLGVHW3DUHQW7DJ YRLGUHOHDVH LQWHUIDFH!! 7DJ ,WHUDWLRQ7DJLQWHUIDFH LQWGR$IWHU%RG\ LQWHUIDFH!! ,WHUDWLRQ7DJ YRLGGR$IWHU%RG\ LQWGR6WDUW7DJ LQWGR(QG7DJ YRLGVHW3DJH&RQWH[W3DJH&RQWH[W PRUHPHWKRGV 7DJ6XSSRUW 7DJ6XSSRUWFODVV 6KDUSHQ \RXU SHQFLO SXEOLFYRLGGR7DJWKURZV-VS([FHSWLRQ,2([FHSWLRQ^ 6WULQJ>@PRYLHV ^³6SLGHUPDQ´³6DYHG´³$PHOLH´` IRULQWL LPRYLHVOHQJWKL^ JHW-VS&RQWH[WVHW$WWULEXWH³PRYLH´PRYLHV>L@ JHW-VS%RG\LQYRNHQXOO ` ` 7U\WRPSOHPHQWWKHVDPHIXQFWLRQDOLW\RIWKLV 6LPSOH7DJGR7DJLQD&ODVVLFWDJKDQGOHU$VVXPH WKH7/'LVFRQILJXUHGWRDOORZERG\FRQWHQW // package and imports public class MyIteratorTag extends TagSupport { public int doStartTag() throws JspException { public int doAfterBody() throws JspException { public int doEndTag() throws JspException { } Chapter 10. When even JSTL is not enough Chapter 10. When even JSTL is not enough Head First Servlets and JSP By Bert Bates, Kathy Sierra, Bryan Basham ISBN: 0596005407 Publisher: O'Reilly Prepared for Augusto Jaramillo Forcada, Safari ID: augustojf.cv@gmail.com Print Publication Date: 8/1/2004 User number: 729515 Copyright 2007, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. 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When even JSTL is not enough Chapter 10. When even JSTL is not enough Head First Servlets and JSP By Bert Bates, Kathy Sierra, Bryan Basham ISBN: 0596005407 Publisher: O'Reilly Prepared for Augusto Jaramillo Forcada, Safari ID: augustojf.cv@gmail.com Print Publication Date: 8/1/2004 User number: 729515 Copyright 2007, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited. 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Chapter 10. When even JSTL is not enough Chapter 10. When even JSTL is not enough Head First Servlets and JSP By Bert Bates, Kathy Sierra, Bryan Basham ISBN: 0596005407 Publisher: O'Reilly Prepared for Augusto Jaramillo Forcada, Safari ID: augustojf.cv@gmail.com Print Publication Date: 8/1/2004 User number: 729515 Copyright 2007, Safari Books Online, LLC. This PDF is exclusively for your use in accordance with the Safari Terms of Service. No part of it may be reproduced or transmitted in any form by any means without the prior written permission for reprints and excerpts from the publisher. Redistribution or other use that violates the fair use priviledge under U.S. copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited. [...]...Chapter 10 When even JSTL is not enough Chapter 10 When even JSTL is not enough Head First Servlets and JSP By Bert Bates, Kathy Sierra, Bryan Basham ISBN: 0596005407 Publisher:Prepared for Augusto Jaramillo Forcada, Safari ID: augustojf.cv@gmail.com O'Reilly Print Publication Date: 8/ 1/2004 User number: 729515 Copyright 2007, Safari Books Online, LLC This PDF is exclusively for your... prior written permission for reprints and excerpts from the publisher Redistribution or other use that violates the fair use priviledge under U.S copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited Chapter 10 When even JSTL is not enough Chapter 10 When even JSTL is not enough Head First Servlets and JSP By Bert Bates, Kathy Sierra, Bryan... strictly prohibited Chapter 10 When even JSTL is not enough Chapter 10 When even JSTL is not enough Head First Servlets and JSP By Bert Bates, Kathy Sierra, Bryan Basham ISBN: 0596005407 Publisher:Prepared for Augusto Jaramillo Forcada, Safari ID: augustojf.cv@gmail.com O'Reilly Print Publication Date: 8/ 1/2004 User number: 729515 Copyright 2007, Safari Books Online, LLC This PDF is exclusively for your... prior written permission for reprints and excerpts from the publisher Redistribution or other use that violates the fair use priviledge under U.S copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited Chapter 10 When even JSTL is not enough Chapter 10 When even JSTL is not enough Head First Servlets and JSP By Bert Bates, Kathy Sierra, Bryan... strictly prohibited Chapter 10 When even JSTL is not enough Chapter 10 When even JSTL is not enough Head First Servlets and JSP By Bert Bates, Kathy Sierra, Bryan Basham ISBN: 0596005407 Publisher:Prepared for Augusto Jaramillo Forcada, Safari ID: augustojf.cv@gmail.com O'Reilly Print Publication Date: 8/ 1/2004 User number: 729515 Copyright 2007, Safari Books Online, LLC This PDF is exclusively for your... prior written permission for reprints and excerpts from the publisher Redistribution or other use that violates the fair use priviledge under U.S copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited Chapter 10 When even JSTL is not enough Chapter 10 When even JSTL is not enough Head First Servlets and JSP By Bert Bates, Kathy Sierra, Bryan... strictly prohibited Chapter 10 When even JSTL is not enough Chapter 10 When even JSTL is not enough Head First Servlets and JSP By Bert Bates, Kathy Sierra, Bryan Basham ISBN: 0596005407 Publisher:Prepared for Augusto Jaramillo Forcada, Safari ID: augustojf.cv@gmail.com O'Reilly Print Publication Date: 8/ 1/2004 User number: 729515 Copyright 2007, Safari Books Online, LLC This PDF is exclusively for your... prior written permission for reprints and excerpts from the publisher Redistribution or other use that violates the fair use priviledge under U.S copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited Chapter 10 When even JSTL is not enough Chapter 10 When even JSTL is not enough Head First Servlets and JSP By Bert Bates, Kathy Sierra, Bryan... strictly prohibited Chapter 10 When even JSTL is not enough Chapter 10 When even JSTL is not enough Head First Servlets and JSP By Bert Bates, Kathy Sierra, Bryan Basham ISBN: 0596005407 Publisher:Prepared for Augusto Jaramillo Forcada, Safari ID: augustojf.cv@gmail.com O'Reilly Print Publication Date: 8/ 1/2004 User number: 729515 Copyright 2007, Safari Books Online, LLC This PDF is exclusively for your... prior written permission for reprints and excerpts from the publisher Redistribution or other use that violates the fair use priviledge under U.S copyright laws (see 17 USC107) or that otherwise violates the Safari Terms of Service is strictly prohibited Chapter 10 When even JSTL is not enough Chapter 10 When even JSTL is not enough Head First Servlets and JSP By Bert Bates, Kathy Sierra, Bryan . prohibited. 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