JSP String To Java Class

Question

I have a jsp page. Page have a requested field as string.

<% String token = ""+request.getParameter(); %>

In this jsp page also has a test class.

 <%!
      public static String usetoken()
          {
              String testtoken = ""+token;
          }

 %>

This usetoken class can not solve the token string. How can I solve that ? I need to call a string inside a class which inside a jsp page.

Thanks,

Answer 1

Firstly, as you may know, a jsp will be compiled to a servlet. All scriptlet code will be "inserted" into service() method and all declarations will be inserted to servlet class. So, for your situation, we'll have something like this(simplified):

public class FooServlet extends HttpServlet {

    public static String useToken() {
        String testtoken = ""+ token;
        return testtoken;
    }

    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String token = ""+ request.getParameter();
    }
}

As you see, userToken() method can't know about 'token' local variable inside service() method.

Also, you can't access HttpServletRequest in your jsp declaration, because it's a parameter of service() method.

BUT

You can use JSTL for something like this. You can declare variable:

<c:set var="token" value="${requestScope.token}"/>

And access it anywhere in your jsp using expression language(EL):

${token}

---

If you don't know, writing scriptlets inside your jsp considered bad practice . You need to do business logic somewhere outside and provide view as jsp. So use JSTL, your custom tags and EL.