- Custom Tags = alternatives to java beans for JSP = reduces some limitations of JavaBeans (in JSP) like to few methods to access the bean, you may still require to write much java code in JSP [that we want to avoid]
- Overview:
- Custom tag with no body should extend TagSupport class that implements Tag interface
- Tags extending TagSupport should extend only one method – doStartTag(), and in this case the doStartTag() method should return SKIP_BODY
- A simple tag code is shown below:
- Next you need to define a tld file – a descriptor file for the tag – XML file.
- In the tld files, the most important tag is the tag
- The sub-elements of the tag element are: name, tag-class, description, body-content.
- Sample:
SimpleTag tags.SimpleTag Sample TLD File empty
- To use the custom tag in a JSP file, You need to provide a directive like:
- Example use:
- How to add attributes to tags: In the class, declare private variable for each attribute you want, define a setXXX method for each of the attribute
- In the tld – file, add an attribute tag for each attribute you want. This attribute tag can have following sub-elements: name, required, rtexprvalue = can the value be an expression, type=class to which the value should typecast to, description
- Defining tag body: doStartTag() should return EVAL_VALUE_INCLUDE
- A new method named doEndTag() should be defined that will define what will be the effect on the body text.
- The doEndTag() method may return EVAL_PAGE = continue to process rest of the JSP page, SKIP_PAGE = stop processing rest of the page
- To support body inside the custom tags – body-content tag in the tld file needs to be adjusted: example
SimpleTag tags.SimpleTag Sample TLD File JSP
- Example use: Body Text
From: http://sitestree.com/?p=4964
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Post Data:2012-12-20 05:06:38
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