} } }

    Servlet的MVC模式(策画一元二次方程的根)

    添加时间:2013-5-14 点击量:

    设计一个Web应用,该Web应用供给两个jsp页面,一个页面是用户输入一元二次方程的系数,另一个显示一元二次方程的系和根。Web应用供给一个名字为handle的servlet对象,handle负责策画一元二次方程的根,然后将有关数据存储到JavaBean中;Web应用供给的javaBean负责描画一个一元二次方程,供给简单的获取数据和批改数据的办法。


    用户须要为web.xml文件添加的如下字标识表记标帜:



    1 <servlet>
    
    2 <servlet-name>handle</servlet-name>
    3 <servlet-class>sun.yourservlet.HandleData</servlet-class>
    4 </servlet>
    5 <servlet-mapping>
    6 <servlet-name>handle</servlet-name>
    7 <url-pattern>/handleData</url-pattern>
    8 </servlet-mapping>


    1>模型(javabean)



     1 package moon.yourbean;
    
    2
    3 public class Equation
    4 { double a,b,c;
    5 String rootOne,rootTwo;
    6 boolean squareEquation;
    7 public void setA(double a)
    8 { this.a=a;
    9 }
    10 public double getA()
    11 { return a;
    12 }
    13 public void setB(double b)
    14 { this.b=b;
    15 }
    16 public double getB()
    17 { return b;
    18 }
    19 public void setC(double c)
    20 { this.c=c;
    21 }
    22 public double getC()
    23 { return c;
    24 }
    25 public void setRootOne(String root)
    26 { rootOne=root;
    27 }
    28 public String getRootOne()
    29 { return rootOne;
    30 }
    31 public void setRootTwo(String root)
    32 { rootTwo=root;
    33 }
    34 public String getRootTwo()
    35 { return rootTwo;
    36 }
    37 public void setIsSquareEquation(boolean b)
    38 { squareEquation=b;
    39 }
    40 public boolean getIsSquareEquation()
    41 { return squareEquation;
    42 }
    43 }


    2>试图(jsp页面)
    input.jsp



     1 <%@ page contentType=text/html;charset=GB2312 %>
    
    2 <HTML><BODY ><Font size=2>
    3 <FORM action=handleData Method=post >
    4 <BR>输入一元二次方程的系数:
    5 <BR> 二次项系数a:<Input type=text name=a size=4>
    6 一次项系数b:<Input type=text name=b size=4>
    7 常数项c:<Input type=text name=c size=4>
    8 <Input type=submit value=提交>
    9 </FORM>
    10 </Font></BODY></HTML>


    show.jsp



     1 <%@ page contentType=text/html;charset=GB2312 %>
    
    2 <%@ page import=moon.yourbean.%>
    3 <jsp:useBean id=equation type=moon.yourbean.Equation scope=request/>
    4 <HTML><BODY ><Font size=2>
    5 一元二次方程的系数是:
    6 <BR> 二次项系数:<jsp:getProperty name=equation property=a/>
    7 一次项系数:<jsp:getProperty name=equation property=b/>
    8 常数项:<jsp:getProperty name=equation property=c/>
    9 <BR>是一元二次方程吗?<jsp:getProperty name=equation property=isSquareEquation/>
    10 <BR>方程的两个根是:<jsp:getProperty name=equation property=rootOne/>
    11 <jsp:getProperty name=equation property=rootTwo/>
    12 </FONT></BODY></HTML>


    3>把握器(servlet)



     1 package sun.yourservlet;
    
    2 import moon.yourbean.;
    3 import java.io.;
    4 import javax.servlet.;
    5 import javax.servlet.http.;
    6 public class HandleData extends HttpServlet
    7 { public void init(ServletConfig config) throws ServletException
    8 {super.init(config);
    9 }
    10 public void doPost(HttpServletRequest request,HttpServletResponse response)
    11 throws ServletException,IOException
    12 { Equation equ=new Equation(); //创建Javabean对象
    13 request.setAttribute(equation,equ);// 将equ存储到HttpServletRequest对象中
    14 double a=Double.parseDouble(request.getParameter(a));
    15 double b=Double.parseDouble(request.getParameter(b));
    16 double c=Double.parseDouble(request.getParameter(c));
    17 equ.setA(a); //将数据存储在equ中
    18 equ.setB(b);
    19 equ.setC(c);
    20 if(a!=0
    21 equ.setIsSquareEquation(true);
    22 else
    23 equ.setIsSquareEquation(true);
    24 double disk=bb-4ac;
    25 if(disk<0
    26 { equ.setRootOne(无实根);
    27 equ.setRootTwo(无实根);
    28 }
    29 else
    30 { double root1=(-b+Math.sqrt(disk))/(2a),
    31 root2=(-b-Math.sqrt(disk))/(2a);
    32 equ.setRootOne(+root1);
    33 equ.setRootTwo(+root2);
    34 }
    35 RequestDispatcher dispatcher=request.getRequestDispatcher(show.jsp);
    36 dispatcher.forward(request,response); //恳求show.jsp显示equ中的数据
    37 }
    38 public void doGet(HttpServletRequest request,HttpServletResponse response)
    39 throws ServletException,IOException
    40 { doPost(request,response);
    41 }
    42 }


    所有随风而逝的都属于昨天的,所有历经风雨留下来的才是面向未来的。—— 玛格丽特·米切尔 《飘》
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