如何在JSP中传递值 <form> 到一个java方法

Question

I have aa JSP file in this format(two select tags)-

<%@ page import="mypackage.*" %>

<all the main tags>...

<form> 
<select> options... </select> 
<select> options... </select> 
<input type="submit" value="submit" /> 
</form>

<textarea></textarea>

There is a java method inside "mypackage" which should take arguments from the <select> tags after clicking on submit. The method returns a string which I want to output in the <textarea> . How do I go about this ?

Thanks a lot guys.

Answer 1

Send it as HTTP POST or HTTP GET to a servlet, and receive it via doGet() or doPost() methods. You can access it via HttpServletRequest.getParameter() .

void doPost(HttpServletRequest request, HttpServletResponse response)

Answer 2

I see that you are importing the mypackage.* classes into your JSP. Indeed, you could include Java code inside your JSP and call the class directly. Something like:

<%
    MyClass c = new MyClass();
    String result = c.doSomething(request.getParameter("select"));
    out.println("<textarea>" + result + "</textarea>");
%>

should be sufficient (but not good: the result should be escaped).

However, this code is not very maintainable and it can be done better (the answer of kaustav datta is one standard way of doing it).

It can be done in a more elegant way using the Spring framework's MVC part: http://static.springsource.org/spring/docs/3.1.x/spring-framework-reference/html/mvc.html

It needs some configuration at the beginning and takes some time to understand, but when you got it, it is very nice.

In your case, a controller of the following form would be sufficient:

@Controller
public class SelectController {

   private final class MyClass c = new MyClass();

   @RequestMapping(value="/select", method = RequestMethod.POST)
   public String doSelect(@RequestParam("selection") final String selection, final ModelMap model) {
       final String result = c.doSomething(selection);
       modelMap.addAttribute("result", result);

       return "yourJsp";
   }
} 

Answer 3

request.getParameterValues("select")

here getParameterValues is a method of the request interface which returns a string in argument of this method pass name of your controller

when you get value from text box use the method request.getParameter("name");