InsertTag.java

package com.ziqewgww.tag;

import java.util.Hashtable;
import java.util.Stack;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.PageContext;
import javax.servlet.jsp.tagext.TagSupport;

public class InsertTag extends TagSupport {
	private String template;
	private Stack stack;

	// setter method for template attribute
	public void setTemplate(String template) {
		this.template = template;
	}

	public int doStartTag() throws JspException {
		stack = getStack(); // obtain a reference to the template stack
		stack.push(new Hashtable()); // push new hashtable onto stack
		return EVAL_BODY_INCLUDE; // pass tag body through unchanged
	}

	public int doEndTag() throws JspException {
		try {
			pageContext.include(template); // include template
		} catch (Exception ex) { // IOException or ServletException
			throw new JspException(ex.getMessage()); // recast exception
		}
		stack.pop(); // pop hashtable off stack
		return EVAL_PAGE; // evaluate the rest of the page after the tag
	}

	// tag handlers should always implement release() because
	// handlers can be reused by the JSP container
	public void release() {
		template = null;
		stack = null;
	}

	public Stack getStack() {
		// try to get stack from request scope
		Stack s = (Stack) pageContext.getAttribute("template-stack",
				PageContext.REQUEST_SCOPE);
		// if the stack's not present, create a new one and
		// put it into request scope
		if (s == null) {
			s = new Stack();
			pageContext.setAttribute("template-stack", s,
					PageContext.REQUEST_SCOPE);
		}
		return s;
	}
}