新手 servlet求助各位大侠
1、采用Servlet编写程序实现在页面上整数的加(Plus)和减(Minus)的功能,页面效果如下所示。  
请输入两个整数:
操作数1:(文本)   操作数2:(文本)
plus    minus  
------解决方案--------------------
我帮你写了一下,代码如下:
1.index.jsp
<%@ page language="java" import="java.util.*" pageEncoding="gbk"%>
<html>
	<body>
		<form action="MyServlet" method="post">
			<input type="text" name="a" value="${a}">
			<select name="type">
			    <option value="Plus">+</option>
			    <option value="Minus">-</option>
			</select>
			<input type="text" name="b"value="${b}">
			=<input type="text" value="${result}"><input type="submit" value="计算"/><br>
		</form>
	</body>
</html>
2.MyServlet.java
package servlet;
import 
java.io.IOException;
import 
javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class MyServlet extends HttpServlet {
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws 
ServletException, 
IOException {
		int a=request.getParameter("a")==null?0:Integer.parseInt(request.getParameter("a"));
		int b=request.getParameter("b")==null?0:Integer.parseInt(request.getParameter("b"));
		String type=request.getParameter("type");
		int result=0;
		if("Plus".equals(type)){
			result=a+b;
		}else if("Minus".equals(type)){
			result=a-b;
		}
		request.setAttribute("a", a);
		request.setAttribute("b", b);
		request.setAttribute("result", result);
		request.getRequestDispatcher("/index.jsp").forward(request, response);
	}
}
3.web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5"  
	xmlns="http://java.sun.com/xml/ns/javaee"  
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  
	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee  
	http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
 <servlet>
   <servlet-name>MyServlet</servlet-name>
   <servlet-class>servlet.MyServlet</servlet-class>
 </servlet>
 <servlet-mapping>
   <servlet-name>MyServlet</servlet-name>
   <url-pattern>/MyServlet</url-pattern>
 </servlet-mapping>
 <welcome-file-list>
   <welcome-file>index.jsp</welcome-file>
 </welcome-file-list>
</web-app>
------解决方案--------------------
Java code
package com.birdy.rmi;
import java.rmi.Remote;
public interface Calculator extends Remote{
    public long add(long a , long b) throws java.rmi.RemoteException;
    public long sub(long a , long b) throws java.rmi.RemoteException;
}