?? actiondispatcher.java
字號:
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);
}
}
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