7.9. Preventing Double Form Submissions

Problem

You need to stop users from inadvertently submitting a form twice.

Solution

Use the Struts token facility to reject a duplicate request. First, as shown in Example 7-6, save a token in the HTTP request in the Action which precedes the JSP containing the form.

Example 7-6. Action that saves token

package com.oreilly.strutsckbk.ch06;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.struts.action.Action;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;

public class SaveTokenAction extends Action {
    public ActionForward execute(ActionMapping mapping, ActionForm form,
            HttpServletRequest request, HttpServletResponse response)
            throws Exception {
        // save a token
        saveToken(request);

        // load the data to view
        BusinessService.loadData( );
        
        return mapping.findForward("success");
    }
}

You don't have to make any changes to the JSP that displays the form as long as you create the form using the html:form tag (as shown in Example 7-7).

Example 7-7. JSP page for token handling

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib uri="http://struts.apache.org/tags-html" prefix="html" %>

<html>
<head>
  <title>Struts Cookbook - Chapter 7 : Token Test</title> </head> <body bgcolor="white"> <h2>Token Test</h2> <html:errors/> <html:form action="/SaveData"> <html:text property="name"/> <html:submit/> ...

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