actiondispatcher.java

strust 框架 的源程序以及java类源代码

        String name = "unspecified";
        Method method = null;
        try {
            method = getMethod(name);

        } catch (NoSuchMethodException e) {
            String message = messages.getMessage("dispatch.parameter",
                    mapping.getPath(),
                    mapping.getParameter());

            log.error(message);

            throw new ServletException(message);
        }

        return dispatchMethod(mapping, form, request, response, name, method);

    }

    /**
     * <p>Dispatches to the target class' cancelled method, if present, 
     * otherwise returns null. Classes utilizing <code>ActionDispatcher</code> 
     * should provide a <code>cancelled</code> method if they wish to provide 
     * behavior different than returning null.</p>
     */
    protected ActionForward cancelled(ActionMapping mapping,
                                      ActionForm form,
                                      HttpServletRequest request,
                                      HttpServletResponse response)
            throws Exception {

        // Identify if there is an "cancelled" method to be dispatched to
        String name = "cancelled";
        Method method = null;
        try {
            method = getMethod(name);

        } catch (NoSuchMethodException e) {
            return null;
        }

        return dispatchMethod(mapping, form, request, response, name, method);

    }

    // ----------------------------------------------------- Protected Methods


    /**
     * Dispatch to the specified method.
     */
    protected ActionForward dispatchMethod(ActionMapping mapping,
                                           ActionForm form,
                                           HttpServletRequest request,
                                           HttpServletResponse response,
                                           String name) throws Exception {

        // Make sure we have a valid method name to call.
        // This may be null if the user hacks the query string.
        if (name == null) {
            return this.unspecified(mapping, form, request, response);
        }

        // Identify the method object to be dispatched to
        Method method = null;
        try {
            method = getMethod(name);

        } catch (NoSuchMethodException e) {
            String message =
                    messages.getMessage("dispatch.method", mapping.getPath(), name);
            log.error(message, e);

            String userMsg =
                messages.getMessage("dispatch.method.user", mapping.getPath());
            throw new NoSuchMethodException(userMsg);
        }

        return dispatchMethod(mapping, form, request, response, name, method);

    }

    /**
     * Dispatch to the specified method.
     */
    protected ActionForward dispatchMethod(ActionMapping mapping,
                                           ActionForm form,
                                           HttpServletRequest request,
                                           HttpServletResponse response,
                                           String name,
                                           Method method) throws Exception {

        ActionForward forward = null;
        try {
            Object args[] = {mapping, form, request, response};
            forward = (ActionForward) method.invoke(actionInstance, args);

        } catch (ClassCastException e) {
            String message =
                    messages.getMessage("dispatch.return", mapping.getPath(), name);
            log.error(message, e);
            throw e;

        } catch (IllegalAccessException e) {
            String message =
                    messages.getMessage("dispatch.error", mapping.getPath(), name);
            log.error(message, e);
            throw e;

        } catch (InvocationTargetException e) {
            // Rethrow the target exception if possible so that the
            // exception handling machinery can deal with it
            Throwable t = e.getTargetException();
            if (t instanceof Exception) {
                throw ((Exception) t);
            } else {
                String message =
                        messages.getMessage("dispatch.error", mapping.getPath(), name);
                log.error(message, e);
                throw new ServletException(t);
            }
        }

        // Return the returned ActionForward instance
        return (forward);
    }


    /**
     * Introspect the current class to identify a method of the specified
     * name that accepts the same parameter types as the <code>execute</code>
     * method does.
     *
     * @param name Name of the method to be introspected
     * @throws NoSuchMethodException if no such method can be found
     */
    protected Method getMethod(String name)
            throws NoSuchMethodException {

        synchronized (methods) {
            Method method = (Method) methods.get(name);
            if (method == null) {
                method = clazz.getMethod(name, types);
                methods.put(name, method);
            }
            return (method);
        }

    }

    /**
     * <p>Returns the parameter value as influenced by the selected
     * {@link #flavor} specified for this <code>ActionDispatcher</code>.</p>
     *
     * @param mapping  The ActionMapping used to select this instance
     * @param form     The optional ActionForm bean for this request (if any)
     * @param request  The HTTP request we are processing
     * @param response The HTTP response we are creating
     * @return The <code>ActionMapping</code> parameter's value
     */
    protected String getParameter(ActionMapping mapping,
                                  ActionForm form,
                                  HttpServletRequest request,
                                  HttpServletResponse response)
            throws Exception {

        String parameter = mapping.getParameter();
        if ("".equals(parameter)) {
            parameter = null;
        }
        
        if ((parameter == null) && (flavor == DEFAULT_FLAVOR)) {
            // use "method" for DEFAULT_FLAVOR if no parameter was provided
            return "method";
        }

        if ((parameter == null) &&
                ((flavor == MAPPING_FLAVOR || flavor == DISPATCH_FLAVOR))) {
            String message =
                    messages.getMessage("dispatch.handler", mapping.getPath());

            log.error(message);

            throw new ServletException(message);
        }

        return parameter;

    }

    /**
     * Returns the method name, given a parameter's value.
     *
     * @param mapping   The ActionMapping used to select this instance
     * @param form      The optional ActionForm bean for this request (if any)
     * @param request   The HTTP request we are processing
     * @param response  The HTTP response we are creating
     * @param parameter The <code>ActionMapping</code> parameter's name
     * @return The method's name.
     */
    protected String getMethodName(ActionMapping mapping,
                                   ActionForm form,
                                   HttpServletRequest request,
                                   HttpServletResponse response,
                                   String parameter)
            throws Exception {


        // "Mapping" flavor, defaults to "method"
        if (flavor == MAPPING_FLAVOR) {
            return parameter;
        }

        // default behaviour
        return request.getParameter(parameter);
    }

    /**
     * <p>Returns <code>true</code> if the current form's cancel button was
     * pressed.  This method will check if the <code>Globals.CANCEL_KEY</code>
     * request attribute has been set, which normally occurs if the cancel
     * button generated by <strong>CancelTag</strong> was pressed by the user
     * in the current request.  If <code>true</code>, validation performed
     * by an <strong>ActionForm</strong>'s <code>validate()</code> method
     * will have been skipped by the controller servlet.</p>
     *
     * @param request The servlet request we are processing
     * @see org.apache.struts.taglib.html.CancelTag
     */
    protected boolean isCancelled(HttpServletRequest request) {

        return (request.getAttribute(Globals.CANCEL_KEY) != null);

    }

}