dynamicadd.java

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package tw.com.javaworld.CH16;

import java.io.*;
import java.util.*;
import javax.servlet.jsp.*;
import javax.servlet.jsp.tagext.*;

public class DynamicAdd extends SimpleTagSupport implements DynamicAttributes {
	
	private ArrayList keys = new ArrayList();
	private ArrayList values = new ArrayList();

	public void doTag() throws JspException, IOException {
	
		JspContext ctx = getJspContext();
		JspWriter out = ctx.getOut();
			
		float num = 0;
		float sum = Float.parseFloat((String)values.get(0));
		out.print(sum); 
			
		for (int i = 1 ; i < keys.size() ; i++) {
			String temp = (String)values.get(i);
			num = Float.parseFloat(temp);
			sum = sum + num;  
			out.print(" + " + num);
		}
			
		out.print(" = " + sum);
		ctx.setAttribute("sum", Float.toString(sum));
			
	}
	
	public void setDynamicAttribute(String uri, String name, Object value) throws JspException {
		keys.add(name);
		values.add(value);
	}
}