我在带有Tomcat Apache的Eclipse中具有DynamicWebApp。
[我的任务：该bean由2个Integer类型的操作数组成，并且算术运算的加法运算符以'+'表示，减法运算符以'-'表示，而乘法运算以'MUL'表示。 Bean返回Integer类型的计算结果。然后实现以下两种情况：
场景1：实现一个合适的Java Servlet，该Java Servlet调用Java Bean。您可以使用自己的HTML页面调用servlet。方案2：实现一个合适的Java服务器页面，该页面使用JSP标准操作重用Java Bean。然后从JSP页面调用您的bean。
html打开，我可以计算。提交后没有打开任何内容，但我可以在浏览器URL中看到我写的内容。并且如果我启动jsp而不是得到：在类型为（bean.CalculatorBean）的bean中找不到有关属性（firstNum）的任何信息。
我的html代码叫做：[[index.html
<!DOCTYPE html>
<html>
<head>
<meta charset="ISO-8859-1">
<title>Hallo Welt</title>
</head>
<body>
<form action="HalloServlet" method="get" style="text-align: center">
<table border="1" width="25%">
<tr style="text-align: center">
<td colspan="2">Rechner</td>
<td></td>
</tr>
<tr>
<td>Zahl 1</td>
<td><input type="text" name="firstNum"></td>
</tr>
<tr>
<td>Operator</td>
<td><select name="operator">
<option value="+">+</option>
<option value="-">-</option>
<option value="*">MUL</option>
</select></td>
</tr>
<tr>
<td>Zahl 2</td>
<td><input type="text" name="secondNum"></td>
</tr>
<tr>
<td colspan="2"><input type="submit" value="="></td>
</tr>
</table>
</form>
</body>
</html>
被称为servlet：HalloServlet.java
package calculator;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import bean.CalculatorBean;
@WebServlet("/HalloServlet")
public class HalloServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// TODO Auto-generated method stub
response.getWriter().append("Served at: ").append(request.getContextPath());
// Get Parameter from index.html
int operand1 = Integer.parseInt(request.getParameter("firstNum"));
int operand2 = Integer.parseInt(request.getParameter("secondNum"));
char operator1 = request.getParameter("operator").charAt(0);
// Parameter from HalloServlet.java to CalculatorBean
CalculatorBean.setFirstNum(operand1);
CalculatorBean.setSecondNum(operand2);
CalculatorBean.setOperator(operator1);
// Parameter from CalculatorBean to HalloServlet.java
CalculatorBean.getFirstNum();
CalculatorBean.getSecondNum();
CalculatorBean.getOperator();
int i = Integer.parseInt(request.getParameter("result"));
PrintWriter out = response.getWriter();
out.println(i);
out.flush();
}
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// TODO Auto-generated method stub
response.getWriter().append("Served at: ").append(request.getContextPath());
}
}
bean称为：CalculatorBean.java
package bean;
public class CalculatorBean {
private int firstNum;
private int secondNum;
private char operator = '+';
private int result;
public static void getFirstNum() {
}
public static void setFirstNum(int firstNum) {
}
public static void getSecondNum() {
}
public static void setSecondNum(int secondNum) {
}
public static void getOperator() {
}
public static void setOperator(char operator) {
}
public int getResult() {
return result;
}
public void setResult(int result) {
this.result = result;
}
public void calculate() {
switch (this.operator) {
case '+': {
this.result = this.firstNum + this.secondNum;
break;
}
case '-': {
this.result = this.firstNum - this.secondNum;
break;
}
case '*': {
this.result = this.firstNum * this.secondNum;
break;
}
}
}
}
jsp称为：HalloJSP.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
</head>
<body>
<jsp:useBean id="CalculatorBean" class="bean.CalculatorBean">
</jsp:useBean>
<jsp:setProperty name="CalculatorBean" property="*" />
<%
CalculatorBean.calculate();
%>
<br />
<hr>
<br /> Ergebnis:
<jsp:getProperty name="CalculatorBean" property="firstNum" />
<jsp:getProperty name="CalculatorBean" property="operator" />
<jsp:getProperty name="CalculatorBean" property="secondNum" />
=
<jsp:getProperty name="CalculatorBean" property="result" />
<br />
<hr>
<br />
<form action="HalloJSP.jsp" method="post" style="text-align: center">
<table border="1" width="25%">
<tr style="text-align: center">
<td colspan="2">Rechner</td>
<td></td>
</tr>
<tr>
<td>Zahl 1</td>
<td><input type="text" name="firstNum"></td>
</tr>
<tr>
<td>Operator</td>
<td><select name="operator">
<option value="+">+</option>
<option value="-">-</option>
<option value="*">MUL</option>
</select></td>
</tr>
<tr>
<td>Zahl 2</td>
<td><input type="text" name="secondNum"></td>
</tr>
<tr>
<td colspan="2"><input type="submit" value="="></td>
</tr>
</table>
</form>
</body>
</html>
web.xml：
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd" id="WebApp_ID" version="4.0">
<display-name>hallowelt</display-name>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
<welcome-file>index.htm</welcome-file>
<welcome-file>index.jsp</welcome-file>
<welcome-file>default.html</welcome-file>
<welcome-file>default.htm</welcome-file>
<welcome-file>default.jsp</welcome-file>
</welcome-file-list>
</web-app>
我在带有Tomcat Apache的Eclipse中有一个DynamicWebApp。我的任务：bean由2个Integer类型的操作数组成，算术运算的文本形式为'+'，'-'和...