Interface SimpleTag

Simple Tag Handlers differ from Classic Tag Handlers in that instead of supporting doStartTag() and doEndTag(), the 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 BodyTag, but 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 needs.

A SimpleTag handler must have a public no-args constructor. Most SimpleTag handlers should extend SimpleTagSupport.

Lifecycle

The following is a non-normative, brief overview of the SimpleTag lifecycle. Refer to the JSP Specification for details.

1. A new tag handler instance is created each time by the container by calling the provided zero-args constructor. Unlike classic tag handlers, simple tag handlers are never cached and reused by the JSP container.
2. The setJspContext() and setParent() methods are called by the container. The setParent() method is only called if the element is nested within another tag invocation.
3. The setters for each attribute defined for this tag are called by the container.
4. If a body exists, the setJspBody() method is called by the container to set the body of this tag, as a JspFragment. If the action element is empty in the page, this method is not called at all.
5. The doTag() method is called by the container. All tag logic, iteration, body evaluations, etc. occur in this method.
6. The doTag() method returns and all variables are synchronized.