priceformattag.java

IBM提供的购物车

package com.webshop.tag;

import javax.servlet.jsp.*;
import javax.servlet.jsp.tagext.*;
import java.util.Hashtable;
import java.io.Writer;
import java.io.IOException;
import java.util.Date;   
import org.apache.struts.taglib.html.Constants;
import org.apache.struts.util.RequestUtils;

import javax.servlet.jsp.JspTagException;
import javax.servlet.jsp.tagext.TagSupport; 
import java.text.DecimalFormat;
import java.text.NumberFormat;
/**
 * @author w
 *
 * To change this generated comment edit the template variable "typecomment":
 * Window>Preferences>Java>Templates.
 * To enable and disable the creation of type comments go to
 * Window>Preferences>Java>Code Generation.
 */

/**
 *演示从TagSupport继承来开发标签
 */
public class PriceFormatTag extends TagSupport
{
   protected String name;//Java Bean的名字
   protected String property;//JavaBean的属性
    protected String format;//要显示的数据的格式
    
   /** 属性方法**/        
   
  public void setName(String name) {
    this.name = name;
  }

  public String getName() {
    return name;
  }


  public void setFormat(String format) {
    this.format = format;
  }

  public String getFormat() {
    return format;
  }

  public void setProperty(String property) {
    this.property = property;
  }

  public String getProperty() {
    return property;
  }
    
    
    /**
     *覆盖doStartTag方法
     */
    public int doStartTag() throws JspTagException {
	return EVAL_BODY_INCLUDE;
    }
    
    /**
     *覆盖doEndTag方法
     */
	public int doEndTag()throws JspTagException
	{
		 try {
      String beanName = Constants.BEAN_KEY;
      if (name != null) {
        beanName = name;
      }
      Object value = RequestUtils.lookup(pageContext, beanName, property, null);
      if (value != null) {
      		String result;
      	NumberFormat formatter = new DecimalFormat(format);
         result=formatter.format(value);
        pageContext.getOut().write(result);
      }

    } catch (IllegalArgumentException e) {
      // nested reference to a property returns null
    } catch (Exception e) {
    	e.printStackTrace();
      throw new JspTagException(e.getMessage());
    }  
		return EVAL_PAGE;
	}
}