MVC模式简单实例：实现简易四则运算器

jisuan.jsp页面提供表单，用户可以通过表单输入两个数以及选择运算符号：

<%@ page language="java" import="java.util.*,ch10.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>



  
    
    
    
    
	
	
	    
	
	
	

  
  
  
    

    
请输入两个数：  
	
请选择符号：
				+(加)
				-(减)
				*(乘)
				/(除)

	
	
	
	
    
    
    

      计算结果为：<%
    messagebean mm=(messagebean)session.getAttribute("mm");
     if(mm==null){%>
     0.00+0.00=0.00
     <%} else{%>
     <%= mm.getOne()%><%= mm.getFuhao() %><%= mm.getTwo() %>=<%=mm.getResult() %>
     <%} %>
  

JAVABean负责存储运算数、运算符号和运算结果：

messagebean.java:

package ch10;

public class messagebean {
	private double one,two,result;
	private String fuhao;
	public double getOne() {
		return one;
	}
	public void setOne(double one) {
		this.one = one;
	}
	public double getTwo() {
		return two;
	}
	public void setTwo(double two) {
		this.two = two;
	}
	public double getResult() {
		return result;
	}
	public void setResult(double result) {
		this.result = result;
	}
	public String getFuhao() {
		return fuhao;
	}
	public void setFuhao(String fuhao) {
		this.fuhao = fuhao;
	}
}

 servlet控制器负责运算，并将运算结果存储在javabean中,并将结果显示在JSP页面中：

chuli.java:

package ch10;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class chuli extends HttpServlet {
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		this.doPost(request, response);
	}

	
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		PrintWriter out=response.getWriter();
		request.setCharacterEncoding("UTF-8");
		response.setContentType("text/html;charset=utf-8");
		String one1=new String(request.getParameter("one").getBytes("ISO-8859-1"),"UTF-8");
		String two1=new String(request.getParameter("two").getBytes("ISO-8859-1"),"UTF-8");
		String fuhao=new String(request.getParameter("select").getBytes("ISO-8859-1"),"UTF-8");
		double one=Double.parseDouble(one1);
		double two=Double.parseDouble(two1);
		double result=0;
		if(one1 == null||two1 == null|| one1.length()==0||two1.length()==0){
			out.print("请先输入：");
		}
		if(fuhao.equals("+")){
			result=one+two;
		}
		if(fuhao.equals("-")){
			result=one-two;
		}
		if(fuhao.equals("*")){
			result=one*two;
		}
		if(fuhao.equals("/")){
			result=one/two;
		}
		messagebean mm=new messagebean();
		mm.setFuhao(fuhao);
		mm.setOne(one);
		mm.setResult(result);
		mm.setTwo(two);
		
		request.getSession().setAttribute("mm", mm);
		response.sendRedirect("jisuan.jsp");
	}

}

运行效果图：