收集到的 JSP Tag 开发方法。

Accepting EL Expressions as Attribute Values 

public static Object evaluate(String attributeName,
  String expression,
  Class expectedType,
  Tag tag,
  PageContext pageContext);

Here's a tag handler that accepts an EL expression as the value of its name attribute: 

package com.ora.jstl;

import java.io.IOException;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.TagSupport;
import org.apache.taglibs.standard.lang.support.ExpressionEvaluatorManager;

public class HelloTag extends TagSupport {
   private String nameEL;

   public void setName(String name) {
      nameEL = name;
   }

   public int doEndTag() throws JspException {
      String name = (String)
      ExpressionEvaluatorManager.evaluate("name", nameEL, 
          String.class, this, pageContext);
      if (name == null || name.length() == 0) {
         name = "World";
      }
      try {
         pageContext.getOut().write("Hello " + name + "!");
      }
      catch (IOException e) {}
      return EVAL_PAGE;
   }
}

From: http://www.onjava.com/lpt/a/2864 

Also to find:
Developing JSTL-Style Conditional Custom Actions 
Developing JSTL-Style Iteration Custom Actions

JSP 2.0 直接 EL Expressions 以及 Tag Page，显得上面的技术不太重要了。