servlet实现简单的计算器

曼路

发布于 2018-10-18 15:32:47

2.3K0

发布于 2018-10-18 15:32:47

文章被收录于专栏：浪淘沙浪淘沙

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。

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:

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:

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

<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

<?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：