myiteratortag.java

关于java的初学者如何使用标签源代码,很容易上手的哦!

package mytag;

import javax.servlet.jsp.*;
import javax.servlet.jsp.tagext.*;
import java.util.Hashtable;
import java.io.Writer;
import java.io.IOException;

import java.util.List;
/**
 * @author  yeeku.H.lee [e-mail]
 * @version  1.0
 * <br>Copyright (C), 2005-2008, yeeku.H.Lee
 * <br>This program is protected by copyright laws.
 * <br>Program Name:
 * <br>Date: 
 */
public class MyIteratorTag extends BodyTagSupport
{
	private String bean;
    private String item;
    private String scope;
    private int i = 0;
    private int size;
    private List<String> itemList = null;

	public void setBean (String s)
	{
		bean  = s;
    }
	public void setScope (String s)
	{
		scope  = s;
    }

	public String getBean ()
	{
		return bean;
    }

	public void setItem (String s)
	{
		item  = s;
    }

	public String getItem ()
	{
		return item;
    }

	public int doStartTag() throws JspTagException
	{
        if (scope.equals("page"))
        {
            itemList = (List<String>)pageContext.getAttribute(bean);
        }
        else if(scope.equals("request"))
        {
            itemList = (List<String>)pageContext.getAttribute(bean ,
                PageContext.REQUEST_SCOPE);
        }
        else if(scope.equals("session"))
        {
            itemList = (List<String>)pageContext.getAttribute(bean ,
                PageContext.SESSION_SCOPE);
        }
        else if(scope.equals("application"))
        {
            itemList = (List<String>)pageContext.getAttribute(bean ,
                PageContext.APPLICATION_SCOPE);
        }
        if (itemList == null)
        {
            System.out.println("集合为空");
            return SKIP_BODY;
        }
        //测试用的
        System.out.println(itemList);
        size = itemList.size();
        pageContext.setAttribute(item , itemList.get(i)); 
        return EVAL_BODY_BUFFERED;
	}

	public int doAfterBody() throws JspException
	{
        System.out.println("标签体结束"); 

        i++ ;
        if (i >= size)
        {
            i = 0;
            return SKIP_BODY;
        }
        pageContext.setAttribute(item , itemList.get(i)); 
        return EVAL_BODY_AGAIN;
	}


	public int doEndTag() throws JspTagException
	{
        if (itemList == null )
        {
            return EVAL_PAGE;
        }
        else
        {
            try
            {
                bodyContent.writeOut(pageContext.getOut());
            }
            catch (IOException ex)
            {
                throw new JspTagException("错误");
            }
            return EVAL_PAGE;
        }
	}
}