I use tomcat 7.0 and JSF 2.1 and I have problem when I call in my .xhtml page something like that: #{homePage.get("userName")}
I get javax.el.ELException: Caused by: java.lang.NullPointerException
at mainPacket.HomePageBean.get(HomePageBean.java:35)
I have ManagedBean like below:
#ManagedBean(name = "homePage")
#ViewScoped
public class HomePageBean {
private Map<String, Object> map;
public HomePageBean() {
map= FacesContext.getCurrentInstance().getExternalContext().getSessionMap();
//remove unnecessary values from sessionMap
FacesContext.getCurrentInstance().getExternalContext().getSessionMap().clear();
}
public String get(Object s){
return map.get(s).toString();
}
}
When I don't use clear, everything works ok. But I want to clear sessionMap. How to resolve it ?
Thanks
Java is an object oriented language. It doesn't give you a copy of the object everytime you request it. No, it gives you a reference to the object instance in memory. At the moment you invoke Map#clear() on the session map, then the map reference which you obtained just beforehand is basically also emptied, because it points to exactly the same map instance which you just emptied!
Your concrete functional requirement is nowhere mentioned in the question and the whole design in the code posted so far makes honestly no utter sense (I can't imagine any sensible real world use case for this), so it's hard to propose you the right solution. Best what you can get is the advice to add a nullcheck.
public String get(Object s){
Object value = map.get(s);
return (value != null) ? value.toString() : null;
}
You should by the way be very careful with abruptly emptying the session map this way. JSF stores view scoped and session scoped managed beans in there and it's also used by the flash scope.
Related
I'm building REST API on the top of Spring Data Rest. Initially all repositories where extending JpaRepository. Lately decision has been made to take a more flexible approach and use QueryDslPredicateExecutor<T> along with QuerydslBinderCustomizer<Q>.
Pretty much all findAll methods exposed in repositories should address two scenarios
principal has a role ROLE_ADMIN then no filtering should be applied a part from Pageable,Sort
principal does not have a role ROLE_ADMIN I would return only those entities which belong to the current user
Getting that done was as simple as annotating findAll method as below.
#Query("select e from Entity e where e.field = ?#{principal} or 1=?#{hasRole('ROLE_ADMIN') ? 1 : 0}")
Page<Entity> findAll(Pageable pageable);
Now I want our findAll to be something similar to below
Page<Entity> findAll(Predicate predicate, Pageable pageable)
Predicate is being build from request parameters(courtesy of #QuerydslPredicate) and is being passed in to RepositoryEntityController which is all being managed by spring-data-rest which is great.
#ResponseBody
#RequestMapping(value = BASE_MAPPING, method = RequestMethod.GET)
public Resources<?> getCollectionResource(#QuerydslPredicate RootResourceInformation resourceInformation,
DefaultedPageable pageable, Sort sort, PersistentEntityResourceAssembler assembler)
throws ResourceNotFoundException, HttpRequestMethodNotSupportedException {
I want to tweak that predicate(2 scenarios as above that I want to address).
It would be something simialr to below.
BooleanBuilder builder = new BooleanBuilder(predicateBuildFromHttpRequest);
builder.and(predicateAddressingOurRequirements);
builder.getValue();
#PostFilter won't be an option as return type for all repos is Page<Entity>.
Use case that I want to address seems to be quite common to me. Having said that I had a look at spring-data and spring-data-rest documentation and could not find anything related to my question.
Question is : Am I missing something obvious here and there is a quick win for it? or I would need to implement custom solution myself? Any comments very much appreciated!
The Querydsl predicates are constructed by QuerydslAwareRootResourceInformationHandlerMethodArgumentResolver which is sadly package private and can't be directly extended.
However, you can make a copy of that, add your security predicate logic and then drop in your implementation instead of the former resolver.
public class MyQueryDslRootResourceArgumentResolver extends RootResourceInformationHandlerMethodArgumentResolver {
// the most of the code is ommitted, the content is identical with
// QuerydslAwareRootResourceInformationHandlerMethodArgumentResolver,
// the important part is postProcessMethod where you can modify the predicate
#Override
#SuppressWarnings({"unchecked"})
protected RepositoryInvoker postProcess(MethodParameter parameter, RepositoryInvoker invoker,
Class<?> domainType, Map<String, String[]> parameters) {
Object repository = repositories.getRepositoryFor(domainType);
if (!QueryDslPredicateExecutor.class.isInstance(repository)
|| !parameter.hasParameterAnnotation(QuerydslPredicate.class)) {
return invoker;
}
ClassTypeInformation<?> type = ClassTypeInformation.from(domainType);
QuerydslBindings bindings = factory.createBindingsFor(null, type);
// modify your predicate here
Predicate predicate = predicateBuilder.getPredicate(type, toMultiValueMap(parameters), bindings);
return new QuerydslRepositoryInvokerAdapter(invoker, (QueryDslPredicateExecutor<Object>) repository, predicate);
}
}
Then add you own configuration class with the custom resolver implementation.
public class CustomRepositoryRestMvcConfiguration extends RepositoryRestMvcConfiguration {
#Autowired
ApplicationContext applicationContext;
#Override
public RootResourceInformationHandlerMethodArgumentResolver repoRequestArgumentResolver() {
QuerydslBindingsFactory factory = applicationContext.getBean(QuerydslBindingsFactory.class);
QuerydslPredicateBuilder predicateBuilder = new QuerydslPredicateBuilder(defaultConversionService(),
factory.getEntityPathResolver());
return new MyQueryDslRootResourceArgumentResolver(repositories(),
repositoryInvokerFactory(defaultConversionService()), resourceMetadataHandlerMethodArgumentResolver(),
predicateBuilder, factory);
}
}
Here is an example project that modifies the Predicate (that is produced by the parameters from url) before passing it to the repository.
The demonstration of what David Siro explained above
https://github.com/yeldarxman/QueryDslPredicateModifier
I am new to spring security, and recently worked on a project that require to do method level security.
I managed to handle it like below:
#Repository
public class EmployeeDaoImpl{
#PreAuthorize("#mySecurityService.canAdd('ROLE_ADMIN') ")
public void addEmployee(EmployeeEntity employee) {
try{
this.sessionFactory.getCurrentSession().save(employee);
}catch(AccessDeniedException e){
}
}
}
#Component
public class MySecurityService {
public boolean canAdd(String user) {
System.out.println("Entered has permission..........");
if(user.equals("ROLE_ADMIN")){
return false;
}
return false;
}
}
so far so good, everthing is working fine and smoothly.
My question here is about performance, how spring behind the scenes handle calling the method in the #PreAuthorize(), do spring do any kind of object/method caching or proxy-ing, or every time call the method by reflection, and how this will affect the performance?
I've did a lot of search and only found this link, it helped me, but do you have any further explaination specific to #PreAuthorize case.
http://spring.io/blog/2007/07/19/debunking-myths-proxies-impact-performance/
Hope my question is clear, Thanks.
First, the expression needs to be parsed, and only then it can be evaluated.
As a result of parsing, the expression is converted into a tree of SpelNodes. In particular, MethodReference is a SpelNode responsible for method calling.
The parsing part is cached well in PreInvocationAuthorizationAdvice.
The details of the implementation of MethodReferencecan be found here:
org.springframework.expression.spel.ast.MethodReference
org.springframework.expression.spel.ast.MethodReference#getValueInternal(...)
org.springframework.expression.spel.support.ReflectiveMethodExecutor
There is caching and the java.lang.reflect.Method reference is evaluated only once (if the target object remains the same type).
So this is pretty the most that could have been done by Spring. Further improvements require byte code generation, which would be an overkill in my opinion.
Is there any way in Struts2 by which I can get list of namespaces in my App ?
I want this as set or list at runtime .
I am using Struts2 RestActionMapper plugin.
When there invalid namespace is specified for valid action, Struts is throwing namespace error.
But I could not redirected to standard error page when this error occurs. I tried almost all options e.g.global error mapping default namespace etc . Nothing worked. So thought it would be great if I could get list of namespaces in my app, thus i could have checked invalid namespace against my list of valid namespaces and accordingly I could have thrown generic error which would finally result in my standard error page.
I am looking for how to get list of all namespaces in my project.
So basically I want to do something like this.
validNamespaces = getNamespaces();
if(validNamespaces.contains(namespaceRetrivedFromRestPlugin))
{Sysout("This is valid namespace.")}
else
{Sysout("Invalid namespace");}
This is possible, though like Steven has pretty much stated, I'm not convinced that this is the right approach to the problem you state of redirecting to an error page. But, I'll leave that part up to you and use this space to answer the namespace question.
This code will have to be in a Struts2-created object for the injection to work.
private Configuration configuration;
#Inject
public void setConfiguration(Configuration config) {
this.configuration = config;
}
protected Set<String> getNamespaces() {
Set<String> namespaces = Collections.emptySet();
Map<String, Map<String, ActionConfig>> allActionConfigs = this.configuration.getRuntimeConfiguration().getActionConfigs();
if (allActionConfigs != null) {
namespaces = allActionConfigs.keySet();
}
return namespaces;
}
The configuration can also be obtained from a ConfigurationManager. Also, you would obviously want to store these in a variable rather than calling above method over and over. If your object is, say, an interceptor, then you could call this method from the init() method and store it in a class-level variable.
I am writing a (composite) component that needs to interact with my DAO. Here is how the Java part is declared:
#FacesComponent(value="selectLocation")
public class SelectLocation extends UINamingContainer {
To get the DAO object, I tried the CDI annotation:
#Inject private LocationControl lc;
And that didn't work so I tried the Faces annotation:
#ManagedProperty (value = "#{locationControl}") private LocationControl lc;
Both cases nothing happens -- the property lc ends up as null after the constructor finishes.
I use CDI in all my backing beans and it all works. This would be using Weld inside GlassFish 3.1.1. Any suggestions on how to get the resource?
I have a work-around for now, which is to basically put in the boiler-plate code that CDI et. al. is supposed to do away with. I now have this method:
public LocationControl getLocationControl() {
if (lc != null) return lc;
FacesContext fc = getFacesContext();
Object obj = fc.getApplication().evaluateExpressionGet(fc, "#{locationControl}", LocationControl.class);
if (obj instanceof LocationControl) lc = (LocationControl) obj;
return lc;
}
I would like to know if anyone has a better solution.
I don't know if it also works for components, but with CDI + MyFaces CODI you have #Advanced to mark e.g. Phase-Listeners which should be able to use #Inject. If it doesn't work, you could create a feature request in their JIRA. They are pretty fast and there are frequent releases.
Or you use:
MyBean myBean = BeanManagerProvider.getInstance().getContextualReference(MyBean.class);
manually.
There is a way to do this work without workarounds?
Yes, just use a backing bean the usual way.
<x:someComponent value="#{someBean.someProperty}" />
Wrap if necessary in a reusable tagfile/composite to keep it DRY:
<my:someComponent />
I am attempting to create an AttachedProperty for a DataGridColumn within Silverlight 3.0 and I am having some issues.
Here is the AttachedProperty:
public class DataGridColumnHelper
{
public static readonly DependencyProperty HeaderProperty =
DependencyProperty.RegisterAttached("Header", typeof(string), typeof(DataGridColumnHelper),
new PropertyMetadata(OnHeaderPropertyChanged));
private static void OnHeaderPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
string header = GetHeader(d);
var dataGridColumn = d as DataGridColumn;
if (dataGridColumn == null)
{
return;
}
dataGridColumn.Header = GetHeader(dataGridColumn);
}
public static string GetHeader(DependencyObject obj)
{
return (string)obj.GetValue(HeaderProperty);
}
public static void SetHeader(DependencyObject obj, string value)
{
obj.SetValue(HeaderProperty, value);
}
}
As you can see it is really simple, I am trying to overcome the limitation that the Header Property in the DataGridColumn class cannot be bound.
This XAML works as expected...
<Controls:DataGridTextColumn Binding="{Binding OwnerName}"
HeaderStyle="{StaticResource DataGridColumnHeaderStyle}"
Behaviors:DataGridColumnHelper.Header="User Name"/>
However this XAML throws an error...(Specifically: {System.Windows.Markup.XamlParseException: AG_E_PARSER_PROPERTY_NOT_FOUND [Line: 224 Position: 112]
at System.Windows.Application.LoadComponent(Object component, Uri resourceLocator)
....})
<Controls:DataGridTextColumn Binding="{Binding OwnerName}"
HeaderStyle="{StaticResource DataGridColumnHeaderStyle}"
Behaviors:DataGridColumnHelper.Header="{Binding Resources.UserNameListViewHeading, Source={StaticResource Labels}}"/>
Just for experimentation I attached this property (with the binding syntax above) to a DataGrid and checked the DataGridColumnHelper.Header property in the OnHeaderPropertyChanged method and the value was correct (and an exception wasn't thrown)
It is my understanding that the object that the AttachedProperty is attached to must be a DependencyProperty. Looking through Reflector, DataGridColumn (from which DataGridTextColumn derives) derives from DependencyProperty.
Can somebody please shed some light on this? I am trying to Localize our application, and I am having trouble with the DataGrid. I am sure I can do this in code-behind, but I am trying to avoid that.
Chris, the problem is very simple, this won't work because the DataGridTextColumn is "detached" from the Visual Tree. Your DataGridTextColumn object is rooted in the Columns collection of the DataGrid - see the indirection. So even attached properties will not work as you expect. Now there is a way to make all this work using something I'm calling Attached Bindings, see:
http://www.orktane.com/Blog/post/2009/09/29/Introducing-nRouteToolkit-for-Silverlight-(Part-I).aspx
Just remember to attach the binding properties using something that is in the VisualTree (so the Grid holding the column would do just fine.)
Hope this helps.
Try using this, im assuming UserName is a property in your viewmodel
<Controls:DataGridTextColumn Binding="{Binding OwnerName}"
HeaderStyle="{StaticResource DataGridColumnHeaderStyle}"
Behaviors:DataGridColumnHelper.Header="{Binding UserName}"/>
I cant test your scenario so my post is just an idea. Might work, might not.