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,

I hope this is usefull for you https://stackoverflow.com/questions/33183108/how-to-print-a-java-string-in-a-jsp-file — ottis79, Sep 15 '17 at 13:09
@ottis79 no it is not. Please read carrefully. I can use like that. But I can not insert token string to class. — Emin, Sep 15 '17 at 13:13
`token` is a local variable, not existing in definition context (i.e. inside `<%! ... %>` block) — Jozef Chocholacek, Sep 15 '17 at 13:15
@JozefChocholacek I know that but inside <%! ... %> request is not working. — Emin, Sep 15 '17 at 13:16

score 1 · Answer 1 · answered Sep 15 '17 at 14:17

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.

JSP String To Java Class

1 Answers1