Calling a java method in jsp

Question

I have a java class which performs some operations on files. Since the java code is huge I don\'t want to write this code in jsp. I want to call the methods in jsp whenever

Answer 1

Depending on the kind of action you'd like to call, there you normally use taglibs, EL functions or servlets for. Java code really, really doesn't belong in JSP files, but in Java classes.

If you want to preprocess a request, use the Servlet doGet() method. E.g.

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    // Preprocess request here.
    doYourThingHere();
    // And forward to JSP to display data.
    request.getRequestDispatcher("page.jsp").forward(request, response);
}

If you want to postprocess a request after some form submit, use the Servlet doPost() method instead.

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    // Postprocess request here.
    doYourThingHere();
    // And forward to JSP to display results.
    request.getRequestDispatcher("page.jsp").forward(request, response);
}

If you want to control the page flow and/or HTML output, use a taglib like JSTL core taglib or create custom tags.

If you want to execute static/helper functions, use EL functions like JSTL fn taglib or create custom functions.