前台代码
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>计算器</title>
</head>
<body>
<form action="//cal" method="post">
<input type="text" name="first" value="">
<select name="holder">
<option>+</option>
<option>-</option>
<option>*</option>
<option>/</option>
</select>
<input type="text" name="second" value="">
<input type="submit" name="dengyu" value="=">
<input type="text" name="result" value="">
</form>
</body>
</html>
后台Java代码：
package calculator;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.sound.midi.Sequence;
public class calculator extends HttpServlet{
private static final long serialVersionUID = 1L;
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
// TODO Auto-generated method stub
Integer result=1;
req.setCharacterEncoding("UTF-8");
resp.setContentType("text/html;charset=UTF-8");
String second=req.getParameter("second");
System.out.println(second);
if((req.getParameter("first")!=null||"".equals(req.getParameter("first")))&&(req.getParameter("second")!=null||"".equals(req.getParameter("second")))) {
System.out.println("fajdsfkdsfsdk");
Integer num1=Integer.valueOf(req.getParameter("first"));
Integer num2=Integer.valueOf(req.getParameter("second"));
switch (req.getParameter("holder")) {
case "+":
result=num1+num2;
break;
case "-":
result=num1-num2;
break;
case "*":
result=num1*num2;
break;
case "/":
result=num1/num2;
break;
default:
System.out.println("您输入有误，请重新输入");
break;
}
}
PrintWriter out=resp.getWriter();
System.out.println("fajdsfkdsfsdk");
out.println("<form action='/calculator' method='post'>");
out.println("<input name='first' value='"
+ (req.getParameter("first")==null?"":req.getParameter("first")) +"' />");
out.println("<select name='holder'>");
if("+".equals(req.getParameter("holder")))
{
out.println("<option selected='true'>+</option>");
}
else {
out.println("<option>+</option>");
}
if("-".equals(req.getParameter("holder")))
{
out.println("<option selected='true'>-</option>");
}
else {
out.println("<option>-</option>");
}
if("*".equals(req.getParameter("holder")))
{
out.println("<option selected='true'>*</option>");
}
else {
out.println("<option>*</option>");
}
if("/".equals(req.getParameter("holder")))
{
out.println("<option selected='true'>/</option>");
}
else {
out.println("<option>/</option>");
}
out.println("</select>");
out.println("<input name='second' value='"
+ (req.getParameter("second")==null?"":req.getParameter("second")) +"' />");
out.print("<input type='submit' name='dengyu' value='=' />");
out.println("<input name='result' value='"+result+"' />");
out.println("</form>");
}
}