servlet实现简单的计算器

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从今天开始，我会将这学期陆续学习的一些知识，发到网上，也会不断添加新的知识点。 今天，先用servlet编写一个简易的计算器。使用eclipse或myeclipse编写（需要配置jdk,tomcat.可以去其他博客下找教程） 首秀创建一个webproject工程，自己起名字。如果是用eclispe 编写的，那么要选择(Dynamic web project)，并且一步一步的创建，最后一部要选择创建web.xml文件。

记得勾选Generate web.xml

接下来进入正文：

本次共需要写4个部分： Cal.java ：计算器的基本文件。即构成 CalServlet.java：逻辑文件，前台提交数据，进行处理，返回结果。 Cal.jsp：前台界面 ，用户输入信息并可得到结果。 web.xml:配置文件

Cal.jsp:

代码语言：javascript
复制
package Calculator;

public class Cal {

private float num1;

private String op;

private float num2;

public float getNum1() {

return num1;

}

public void setNum1(float num) {

this.num1 = num;

}

public String getOp() {

return op;

}

public void setOp(String op) {

this.op = op;

}

public Float getNum2() {

return num2;

}

public void setNum2(float num2) {

this.num2 = num2;

}


}

CalServlet.java:

代码语言：javascript
复制
package CalServlet;


import java.io.IOException;


import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;


import Calculator.Cal;


public class CalServlet extends HttpServlet {


/**
 * Constructor of the object.
 */
public CalServlet() {
    super();
}

/**
 * The doGet method of the servlet. <br>
 *
 * This method is called when a form has its tag value method equals to get.
 * 
 * @param request the request send by the client to the server
 * @param response the response send by the server to the client
 * @throws ServletException if an error occurred
 * @throws IOException if an error occurred
 */
public void doGet(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    Cal cal=new Cal();
    cal.setNum1(Float.parseFloat( request.getParameter("num1")));
    cal.setNum2(Float.parseFloat( request.getParameter("num2")));
    cal.setOp(request.getParameter("op"));
    float result=0;
    switch(cal.getOp().charAt(0)){
       case '+':result=cal.getNum1()+cal.getNum2();break;
       case '-':result=cal.getNum1()-cal.getNum2();break;
       case '*':result=cal.getNum1()*cal.getNum2();break;
       case '/':result=cal.getNum1()/cal.getNum2();

    }
    request.setAttribute("cal", cal);
    request.setAttribute("result", result);
    request.getRequestDispatcher("../Cal.jsp").forward(request, response);
}

/**
 * The doPost method of the servlet. <br>
 *
 * This method is called when a form has its tag value method equals to post.
 * 
 * @param request the request send by the client to the server
 * @param response the response send by the server to the client
 * @throws ServletException if an error occurred
 * @throws IOException if an error occurred
 */
public void doPost(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {

}



}

Cal.jsp

代码语言：javascript
复制
<body>

<form action="servlet/CalServlet"  method="get">

操作数1：<input type="text" name="num1" value="${requestScope.cal.num1}"><br>

操作符号：<input type="radio" name="op" value="+"${requestScope.cal.op=="+"?"checked":""}>+

<input type="radio" name="op" value="-" ${requestScope.cal.op=="-"?"checked":""}>-

<input type="radio" name="op" value="" ${requestScope.cal.op==""?"checked":""}>*

<input type="radio" name="op" value="/" ${requestScope.cal.op=="/"?"checked":""}>/<br>

操作数2：<input type="text" name="num2" value=" ${requestScope.cal.num2 }"><br>

<input type="submit" value="计算"><br>

结果：   <input type="text" value="${requestScope.result} ">

</form>

</body>

web.xml

代码语言：javascript
复制
<?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">

<display-name></display-name>

<servlet>

<description>This is the description of my J2EE component</description>

<display-name>This is the display name of my J2EE component</display-name>

<servlet-name>CalServlet</servlet-name>

<servlet-class>CalServlet.CalServlet</servlet-class>

</servlet>


<servlet-mapping>

<servlet-name>CalServlet</servlet-name>

<url-pattern>/servlet/CalServlet</url-pattern>

</servlet-mapping>

<welcome-file-list>

<welcome-file>index.jsp</welcome-file>

</welcome-file-list>

</web-app>

运行结果：

这里写图片描述

如果有不懂的地方，欢迎评论。

#servlet#eclipse#jdk#tomcat#xml