下面是用jsp、servlet开发的一简单的web应用。需求描述如下：用jsp、servlet等技术开发一个网站应用程序，实现两个整数的加减乘(除暂时不考虑)运算。现有如下应用程序，请尽可能的指出其中存在的问题，并修正。其中采用jsp1.2，servlet2.3，在tomcat 4服务器上运行。
程序介绍如下：
有两个jsp文件，index.jsp显示输入两个数据和一个运算符号，提交到servlet----MathServlet进行运算，运算的结果在result.jsp页面上显示：
index.jsp代码如下:
<%@ page contentType="text/html;charset=gb2312" language="java" %>
<html>
<head><title>test java </title></head>
<body>Place your content here</body>
<FORM METHOD=POST ACTION="<%=request.getContextPath()%>/MathServlet">
<BR>
<BR> <INPUT NAME="p1" VALUE="">
<BR> <INPUT NAME="p2" VALUE="">
<BR> <INPUT NAME="method" VALUE="">
<BR> <INPUT TYPE=SUBMIT VALUE="submit">
</FORM>
</html>
result.jsp代码如下:
<%@ page contentType="text/html;charset=gb2312" language="java" %>
<%
int result=request.getParameter("reslut");
%>
<html>
<br>
<%=result%>
</html>
servlet----MathServlet代码如下:
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.ServletException;
import java.io.IOException;
public class MathServlet extends HttpServlet {
private int a;
private int b;
private String mathMethod;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doPost(request,response);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
a=new Integer(request.getParameter("p1")).intValue();
b=new Integer(request.getParameter("p2")).intValue();
mathMethod=request.getParameter("method");
int result=Canculate();
request.setAttribute("result",new Integer(result).toString());
getServletConfig().getServletContext().getRequestDispatcher("/result.jsp").forward(request, response);
}
public int Canculate() throws ServletException{
MathBean mathBean=new MathBean(a,b);
int result=0;
if(mathMethod=="+"){
result=mathBean.add();
}else if(mathMethod=="-"){
result=mathBean.substract();
}else if(mathMethod=="*"){
result=mathBean.multiple();
}else{
throw new ServletException("参数错误");
}
return result;
}
}
其中MathBean代码如下:
public class MathBean {
int a;
int b;
public MathBean(int a,int b){
this.a=a;
this.b=b;
}
//加
public int add(){
return a+b;
}
//减
public int substract(){
return a-b;
}
//乘
public int multiple(){
return a*b;
}
}
部署文件web.xml如下：
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd">
<web-app>
<servlet>
<servlet-name>MathServlet</servlet-name>
<servlet-class>MathServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>MathServlet</servlet-name>
<url-pattern>/MathServlet</url-pattern>
</servlet-mapping>
</web-app>