struts 1.xフォームの重複提出を防止します.

public class PrepareTokenAction extends Action {
    public ActionForward execute(
        ActionMapping mapping,
        ActionForm form,
        HttpServletRequest request,
        HttpServletResponse response)
        throws Exception {

        // Generate a unique token that will be
        // check when the form is submitted
        saveToken(request);


        // Forward to the form
        return mapping.findForward("success");

    }
}

public class ProcessTokenAction extends Action {
public ActionForward execute(
        ActionMapping mapping,
        ActionForm form,
        HttpServletRequest request,
        HttpServletResponse response)
        throws Exception {

        // If user pressed 'Cancel' button,
        // return to home page
        if (isCancelled(request)) {
            return mapping.findForward("home");
        }

        ActionErrors errors = new ActionErrors();

        // Prevent unintentional duplication submissions by checking
        // that we have not received this token previously
        if (!isTokenValid(request)) {
            errors.add(
                ActionMessages.GLOBAL_MESSAGE,
                new ActionMessage("errors.token"));
        }
        resetToken(request);

        // Report any errors we have discovered back to the original form
        if (!errors.isEmpty()) {
            saveErrors(request, errors);
            saveToken(request);
            return (mapping.getInputForward());
        }

        // Forward to result page
        return mapping.findForward("success");
    }

}