RequestProcessor类
前面提到过，当ActionServlet接收到客户请求后，会进行一连串的初始化操作，然后，就会将客户请求转交给合适的处理器进行处理，这个合适的处理器就是org.apache.struts.action.RequestProcessor或其子类的一个实例(根据Struts配置文件中的配置)。提供了默认实现，如果需要自定义这些行为，可以重载这个类定义自己的处理行为，当你想要自定义操作时，Struts推荐你重载这个类而不是ActionServlet。
下面的代码片断提供了RequestProcessor的默认行为实现代码：
public void process(HttpServletRequest request, HttpServletResponse response)
throws IOException, ServletException {
// Wrap multipart requests with a special wrapper
request = processMultipart(request);
// Identify the path component we will use to select a mapping
String path = processPath(request, response);
if (path == null) {
return;
}
if (log.isInfoEnabled( )) {
log.info("Processing a '" + request.getMethod( ) +
"' for path '" + path + "'");
}
// Select a Locale for the current user if requested
processLocale(request, response);
// Set the content type and no-caching headers if requested
processContent(request, response);
processNoCache(request, response);
// General-purpose preprocessing hook
if (!processPreprocess(request, response)) {
return;
}
// Identify the mapping for this request
ActionMapping mapping = processMapping(request, response, path);
if (mapping == null) {
return;
}
// Check for any role required to perform this action
if (!processRoles(request, response, mapping)) {
return;
}
// Process any ActionForm bean related to this request
ActionForm form = processActionForm(request, response, mapping);
processPopulate(request, response, form, mapping);
if (!processValidate(request, response, form, mapping)) {
return;
}
// Process a forward or include specified by this mapping
if (!processForward(request, response, mapping)) {
return;
}
if (!processInclude(request, response, mapping)) {
return;
}
// Create or acquire the Action instance to process this request
Action action = processActionCreate(request, response, mapping);
if (action == null) {
return;
}
// Call the Action instance itself
ActionForward forward =
processActionPerform(request, response, action, form, mapping);
// Process the returned ActionForward instance
processActionForward(request, response, forward);
}