{"id":1712,"date":"2011-03-17T17:14:15","date_gmt":"2011-03-17T11:44:15","guid":{"rendered":"http:\/\/JitendraZaa.com\/blog\/?p=1712"},"modified":"2011-03-17T17:14:15","modified_gmt":"2011-03-17T11:44:15","slug":"life-cycle-of-jsp-tag-interface","status":"publish","type":"post","link":"https:\/\/www.jitendrazaa.com\/blog\/java\/jsp\/life-cycle-of-jsp-tag-interface\/","title":{"rendered":"Life cycle of JSP Tag interface"},"content":{"rendered":"

Tag interface:<\/strong>
\nThe interface of a classic tag handler that does not want to manipulate its body<\/strong>. The Tag interface defines the basic protocol between a Tag handler and JSP page implementation class.<\/p>\n

Properties:<\/strong>
\nThe Tag interface specifies the setter and getter methods for the core pageContext <\/strong>and parent <\/strong>properties.<\/p>\n

Methods:<\/strong>
\nThere are two main actions: doStartTag <\/strong>and doEndTag<\/strong>. Once all appropriate properties have been initialized, the doStartTag and doEndTag methods can be invoked on the tag handler. Between these invocations, the tag handler is assumed to hold a state that must be preserved. After the doEndTag invocation, the tag handler is available for further invocations (and it is expected to have retained its properties).<\/p>\n

Empty and Non-Empty Action:<\/strong>
\nIf the TagLibraryDescriptor file indicates that the action must always have an empty action, by an entry of “empty”, then the doStartTag() method must return SKIP_BODY<\/em>.
\nOtherwise, the doStartTag() method may return SKIP_BODY<\/em> or EVAL_BODY_INCLUDE<\/em>.<\/p>\n

If SKIP_BODY <\/em>is returned the body, if present, is not evaluated.
\nIf EVAL_BODY_INCLUDE <\/em>is returned, the body is evaluated and “passed through” to the current out.<\/p>\n

Life Cycle:<\/strong><\/p>\n

\"Life<\/a>
Life Cycle of Tag Interface<\/figcaption><\/figure>\n

1.The tags may have the default values, so the default values are readed and after that setPageContext()<\/strong>, setParent()<\/strong> and the setters <\/strong>of all the attributes are invoked.
\n2. After the initialization of all the properties doStartTag() <\/strong>method is envoked. It may return SKIP_BODY <\/em>or EVAL_BODY_INCLUDE<\/em>.
\n3. doEndTag()<\/strong> is called if and only if the tag ends normally without raising an exception.
\n4. Some setters may be called again before tag handler is reused.
\n<\/strong><\/p>\n

Example :<\/strong> setParent() is called if it is reused within the same page but at different level, setPageContext() is called if its used in another page and attribute setters are called if the values differs.<\/p><\/blockquote>\n

5.Once all invocations on the tag handler are completed, the release()<\/strong> method is invoked on it. Once a release method is invoked all properties, including parent and pageContext, are assumed to have been reset to an unspecified value. The page compiler guarantees that release() will be invoked on the Tag handler before the handler is released to the GC.<\/strong><\/p>\n

<\/strong>Next article :\u00a0Life Cycle of JSP “BodyTag” interface<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"

Life cycle of JSP Tag interface in Java<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"advanced_seo_description":"","jetpack_seo_html_title":"","jetpack_seo_noindex":false,"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"jz_research_post":"","_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[4],"tags":[330],"class_list":["post-1712","post","type-post","status-publish","format-standard","hentry","category-jsp","tag-jsp"],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack-related-posts":[{"id":1716,"url":"https:\/\/www.jitendrazaa.com\/blog\/java\/jsp\/life-cycle-of-jsp-bodytag-interface\/","url_meta":{"origin":1712,"position":0},"title":"Life cycle of JSP BodyTag interface","author":"Jitendra","date":"March 17, 2011","format":false,"excerpt":"Life cycle of JSP BodyTag interface","rel":"","context":"In "JSP"","block_context":{"text":"JSP","link":"https:\/\/www.jitendrazaa.com\/blog\/category\/java\/jsp\/"},"img":{"alt_text":"Life cycle of IterationTag and BodyTag interface in JSP","src":"https:\/\/i0.wp.com\/jitendrazaa.com\/blog\/wp-content\/uploads\/2011\/03\/Life-cycle-of-IterationTag-and-BodyTag-interface-in-JSP.jpg?resize=350%2C200&ssl=1","width":350,"height":200},"classes":[]},{"id":1724,"url":"https:\/\/www.jitendrazaa.com\/blog\/java\/how-to-create-jsp-custom-tag-using-bodytag-interface-or-bodytagsupport\/","url_meta":{"origin":1712,"position":1},"title":"How to Create JSP Custom Tag \u2013 using BodyTag interface or BodyTagSupport","author":"Jitendra","date":"March 17, 2011","format":false,"excerpt":"Tutorial on How to Create JSP Custom Tag \u2013 using BodyTag interface or BodyTagSupport","rel":"","context":"In "JAVA"","block_context":{"text":"JAVA","link":"https:\/\/www.jitendrazaa.com\/blog\/category\/java\/"},"img":{"alt_text":"How to Create Custom Tag in JSP","src":"https:\/\/i0.wp.com\/jitendrazaa.com\/blog\/wp-content\/uploads\/2011\/03\/How-to-Create-Custom-Tag-in-JSP.jpg?resize=350%2C200&ssl=1","width":350,"height":200},"classes":[]},{"id":1720,"url":"https:\/\/www.jitendrazaa.com\/blog\/java\/how-to-create-jsp-custom-tag-using-tag-interface-or-tagsupport\/","url_meta":{"origin":1712,"position":2},"title":"How to Create JSP Custom Tag \u2013 using Tag interface or TagSupport","author":"Jitendra","date":"March 17, 2011","format":false,"excerpt":"Tutorial of creating JSP Custom Tag \u2013 using Tag interface or TagSupport in JAVA","rel":"","context":"In "JAVA"","block_context":{"text":"JAVA","link":"https:\/\/www.jitendrazaa.com\/blog\/category\/java\/"},"img":{"alt_text":"How to Create Custom Tag in JSP","src":"https:\/\/i0.wp.com\/jitendrazaa.com\/blog\/wp-content\/uploads\/2011\/03\/How-to-Create-Custom-Tag-in-JSP.jpg?resize=350%2C200&ssl=1","width":350,"height":200},"classes":[]},{"id":2017,"url":"https:\/\/www.jitendrazaa.com\/blog\/java\/java-j2ee-interview-questions-1\/","url_meta":{"origin":1712,"position":3},"title":"Java – J2EE Interview Questions – 1","author":"Jitendra","date":"April 15, 2011","format":false,"excerpt":"JAVA - 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