Implement a simple calculator program that requires: Use the Jsp+javabean mode implementation.
The project source code is as follows:
Files: calculator.jsp
<% @ page language = "java" pageEncoding = "UTF-8"%>
<% @ page isErrorPage = "true"%>
<% @ page errorPage = "calculator.jsp"%>
<% @ taglib uri = "http://java.sun.com/jsp/jstl/core" prefix = "c"%>
<! DOCTYPE HTML PUBLIC "-// W3C // DTD HTML 4.01 Transitional // EN">
<html>
<head>
<title> Simple computer </ title>
</ head>
<body>
<%-Create Calculator object-%>
<jsp: useBean id = "cal" class = "cn.zq.domain.Calculator" />
<%-Set value Wildcard * means set all attributes-%>
<jsp: setProperty property = "*" name = "cal" />
The
The
<%-
Calculation
-%>
<c: if test = "$ {empty pageContext.exception}">
<%
cal.calculate ();
%>
</ c: if>
The
The
<hr />
<p> Calculation result: $ {cal.firstNum} $ {cal.operator} $ {cal.secondNum} = $ {cal.result} </ p>
<hr />
The
<%-
Build url
-%>
<c: url var = "formUrl" value = "/ calculator.jsp" />
<form action = "$ {formUrl}" method = "post">
<table border = "1" cellpadding = "2">
<tr>
<td colspan = "2" align = "center"> My calculator </ td>
</ tr>
<tr>
<td> First parameter: </ 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 = "*"> * </ option>
<option value = "/"> / </ option>
</ select>
</ td>
</ tr>
<tr>
<td> Second parameter: </ td>
<td>
<input type = "text" name = "secondNum">
</ td>
</ tr>
<tr>
<td colspan = "2">
<input type = "submit" value = "Calculation" />
</ td>
</ tr>
</ table>
</ form>
</ body>
</ html>
The javabean code used in this article is as follows:
package cn.zq.domain;
public class Calculator {
private String firstNum;
private String operator;
private String secondNum;
private String result;
public String getFirstNum () {
return firstNum;
}
public void setFirstNum (String firstNum) {
this.firstNum = firstNum;
}
public String getOperator () {
return operator;
}
public void setOperator (String operator) {
this.operator = operator;
}
public String getSecondNum () {
return secondNum;
}
public void setSecondNum (String secondNum) {
this.secondNum = secondNum;
}
public String getResult () {
return result;
}
public void setResult (String result) {
this.result = result;
}
public Calculator () {}
public Calculator (String firstNum, String operator, String secondNum,
String result) {
this.firstNum = firstNum;
this.operator = operator;
this.secondNum = secondNum;
this.result = result;
}
The
public void calculate () {
if (operator! = null &&! operator.equals ("")) {
double first = new Double (firstNum);
double second = new Double (secondNum);
char oper = operator.charAt (0);
switch (oper) {
case '+':
result = first + second + "";
break;
case '-':
result = first-second + "";
break;
case '*':
result = first * second + "";
break;
case '/':
result = first / second + "";
break;
default:
throw new RuntimeException ("Unknown operator!");
}
}
}
}
The final result is as follows:
Summary: The previous is just a small exercise, in fact, there are still many defects, and the data has not been verified after submission. Obviously, the jsp + javabean mode is only suitable for simple calculations. If the function to be completed is more complicated, this mode is not suitable. If you do some business processing on the jsp page, it also makes the program chaotic, and finally it is difficult to maintain. The processing of the business logic in the above example is done directly in javabean. In actual projects, business is not so simple, often involving some For the operation of the database, the various components should be separated, so that it will be easier to maintain in the future, and it will also make the programmers enjoyable. If it is a project with a logical hierarchy that is not very good, the maintenance is really disgusting , Driving me crazy.
Simple calculator for JSP practice (using jsp + javabean mode)
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