public class Calculator {public double addition(double num1,double num2) {return num1+num2;}public double subtract(double num1,double num2) {return num1-num2;}public double multiply(double num1,double num2) {return num1*num2;}public double divide(double num1,double num2) {return num1/num2;}
}

    Welcome to out website <br><html:form action="/calc" method="post">
<input type="hidden" name="operate" />
Calculator<br/>
num1:
<input type="text" name="num1"><br/>
num2:
<input type="text" name="num2"><br/>
<button οnclick="doSubmit('doAddition')">加</button>
<button οnclick="doSubmit('doSubtract')">减</button>
<button οnclick="doSubmit('doMultiply')">×</button>
<button οnclick="doSubmit('dodDivide')">÷</button>
</html:form>

<script>function doSubmit(opr){document.forms[0].elements["operate"].value=opr;document.forms[0].submit();}
</script>

public ActionForward doAddition(ActionMapping mapping, ActionForm form,HttpServletRequest request, HttpServletResponse response) {CalcForm calcForm = (CalcForm) form;// TODO Auto-generated method stubCalculator calculator = new Calculator();double result;result= calculator.addition(Double.parseDouble(calcForm.getNum1()), Double.parseDouble(calcForm.getNum2()));request.setAttribute("result", result);return mapping.findForward("result");}public ActionForward doSubtract(ActionMapping mapping, ActionForm form,HttpServletRequest request, HttpServletResponse response) {CalcForm calcForm = (CalcForm) form;// TODO Auto-generated method stubCalculator calculator = new Calculator();double result;result= calculator.subtract(Double.parseDouble(calcForm.getNum1()), Double.parseDouble(calcForm.getNum2()));request.setAttribute("result", result);return mapping.findForward("result");}public ActionForward doMultiply(ActionMapping mapping, ActionForm form,HttpServletRequest request, HttpServletResponse response) {CalcForm calcForm = (CalcForm) form;// TODO Auto-generated method stubCalculator calculator = new Calculator();double result;result= calculator.multiply(Double.parseDouble(calcForm.getNum1()), Double.parseDouble(calcForm.getNum2()));request.setAttribute("result", result);return mapping.findForward("result");}public ActionForward dodDivide(ActionMapping mapping, ActionForm form,HttpServletRequest request, HttpServletResponse response) {CalcForm calcForm = (CalcForm) form;// TODO Auto-generated method stubCalculator calculator = new Calculator();double result;result= calculator.divide(Double.parseDouble(calcForm.getNum1()), Double.parseDouble(calcForm.getNum2()));request.setAttribute("result", result);return mapping.findForward("result");}