public interface SimpleTag extends JspTag
Simple Tag Handlers differ from Classic Tag Handlers in that instead of supporting
SimpleTag interface provides a simple
doTag() method, which is
called once and only once for any given tag invocation. All tag logic, iteration, body evaluations, etc. are to be
performed in this single method. Thus, simple tag handlers have the equivalent power of
with a much simpler lifecycle and interface.
To support body content, the
setJspBody() method is provided. The container invokes the
setJspBody() method with a
JspFragment object encapsulating the body of the tag. The tag
handler implementation can call
invoke() on that fragment to evaluate the body as many times as it
A SimpleTag handler must have a public no-args constructor. Most SimpleTag handlers should extend SimpleTagSupport.
The following is a non-normative, brief overview of the SimpleTag lifecycle. Refer to the JSP Specification for details.
setParent() methods are called by the container. The
setParent() method is only called if the element is nested within another tag invocation.
setJspBody() method is called by the container to set the body of this tag, as
JspFragment. If the action element is empty in the page, this method is not called at all.
doTag() method is called by the container. All tag logic, iteration, body evaluations, etc.
occur in this method.
doTag() method returns and all variables are synchronized.
|Modifier and Type
|Method and Description
Called by the container to invoke this tag.
Returns the parent of this tag, for collaboration purposes.
Provides the body of this tag as a JspFragment object, able to be invoked zero or more times by the tag handler.
Called by the container to provide this tag handler with the
JspContext for this invocation.
Sets the parent of this tag, for collaboration purposes.
void doTag() throws JspException, IOException
The JSP container will resynchronize any AT_BEGIN and AT_END variables (defined by the associated tag file, TagExtraInfo, or TLD) after the invocation of doTag().
JspException - If an error occurred while processing this tag.
SkipPageException - If the page that (either directly or indirectly) invoked this tag is
to cease evaluation. A Simple Tag Handler generated from a tag file must throw this exception if an
invoked Classic Tag Handler returned SKIP_PAGE or if an invoked Simple Tag Handler threw
SkipPageException or if an invoked Jsp Fragment threw a SkipPageException.
IOException - If there was an error writing to the output stream.
void setParent(JspTag parent)
The container invokes this method only if this tag invocation is nested within another tag invocation.
parent - the tag that encloses this tag
void setJspContext(JspContext pc)
JspContext for this invocation. An
implementation should save this value.
pc - the page context for this invocation
void setJspBody(JspFragment jspBody)
This method is invoked by the JSP page implementation object prior to
doTag(). If the action element
is empty in the page, this method is not called at all.
jspBody - The fragment encapsulating the body of this tag.
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