I have a controller (for example. MyManager) where I invoke method (for example myMethod() ) of component class (bean), for example MyComponent. I have I servlet where I want to invoke myMethod() . In servlet I have annotated MyManager by #Autowired annotation , despite this I got NullPointerException. I saw this kind of topic but it is not useful for me. For imagination I write little code :
public class myClass extends HttpServlet {
#Autowired
private MyComponent component;
public void init(ServletConfig config) throws ServletException{
super.init(config);
SpringBeanAutowiringSupport.processInjectionBasedOnCurrentContext(this);
}
protected void doGet(HttpServletRequest req,HttpServletResponse res) throws ... {
List<MyObject> objects =component.myMethod(); // Here is the problem, component is null
}
}
}
I make Spring configuration file "context.xml" and I got bean (component) object, but now I have problem with injected EntityManager in bean object. Now it is null , can anyone help me to solve this problem ? Also update init() method.
public void init(ServletConfig config) throws ServletException{
ApplicationContext con = new ClassPathXmlApplicationContext("context.xml");
component = (MyComponent) con.getBean("myBean");
}
You cannot autowire dependencies like that because Servlets are not Spring Beans. You need to do something like the following:
#Override
public void init() throws ServletException {
super.init();
ApplicationContext applicationContext = WebApplicationContextUtils.getWebApplicationContext(getServletContext());
component= applicationContext.getBean(MyComponent.class);
}
Also drop the #Autowired annotation from component
Related
I have a requirement where I had to use Spring beans inside a POJO class to retrieve a MyDomainClass object. Since Autowiring the beans inside the class which is not managed by Spring isn't possible, I had to explicitly get the ApplicationContext from another util class and retrieve the bean from applicationContext object. Please find the code below
#Component
public class ApplicationContextUtils implements ApplicationContextAware{
private static ApplicationContext applicationContext;
#Override
public void setApplicationContext(ApplicationContext appContext)
throws BeansException {
applicationContext = appContext;
}
public static ApplicationContext getApplicationContext() {
return applicationContext;
}
}
The code for using the applicationContext and retrieving the bean is below
public class MyNonBeanClass{
public MyDomainClass retrieveMyDomainObj(){
ApplicationContext applicationContext=ApplicationContextUtils.getApplicationContext();
TestBean testBean=(TestBean)applicationContext.getBean("testBean");
return testBean.retrieve(param1,param2);
}
}
This code is working as expected and I am able to fetch the beans from the application context successfully. But writing the test case has been challenging to say the least. I am not even sure if we will be able to write the test case for my non bean class but I would still like to try. I am trying to use PowerMock to mock the static invocation of getApplicationContext() in ApplicationContextUtils. But I am unable to get the applicationContext necessary for getting the TestBean object. And a NullPointerException is thrown when the getBean() is called on applicationContext. Please help with this.
#RunWith(PowerMockRunner.class)
#PrepareForTest(ApplicationContextUtils.class)
#ContextConfiguration(classes= { BaseTestContext.class})
public class MyNonBeanClassTest implements ApplicationContextAware{
MyNonBeanClass myNonBeanClass;
ApplicationContext applicationContext;
#Test
public void test_retrieveMyDomainObj(){
myNonBeanClass=new MyNonBeanClass();
PowerMockito.mockStatic(ApplicationContextUtils.class);
when(ApplicationContextUtils.getApplicationContext()).thenReturn(applicationContext);
assertNotNull(myNonBeanClass.retrieveMyDomainObj(param1, param2));
}
#Override
public void setApplicationContext(ApplicationContext appContext) throws BeansException {
// TODO Auto-generated method stub
this.applicationContext=appContext;
}
public ApplicationContext getApplicationContext(){
return this.applicationContext;
}
}
I am looking to lazy load all spring beans when running integration tests that utilize #ContextConfiguration. Ideally I would be able to apply this lazy loading in one place and have it applied to any beans that are loaded via the #ContextConfiguration annotation.
Yes it is.
You can do this using BeanDefinitionRegistryPostProcessor/BeanFactoryPostProcessor.
#Configuration
static class LazyBeans implements BeanDefinitionRegistryPostProcessor {
#Override
public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry bdr) throws BeansException {
for (String name : bdr.getBeanDefinitionNames()) {
final BeanDefinition beanDefinition = bdr.getBeanDefinition(name);
if (beanDefinition.getRole() == BeanDefinition.ROLE_APPLICATION) {
beanDefinition.setLazyInit(true);
}
}
}
#Override
public void postProcessBeanFactory(ConfigurableListableBeanFactory clbf) throws BeansException {}
}
I am trying to do an image upload API. I have a ImageUpload task as follows,
#Component
#Configurable(preConstruction = true)
#Scope(BeanDefinition.SCOPE_PROTOTYPE)
public class ImageUploadTask implements Callable<JSONObject> {
#Autowired
private ImageUploadService imageUploadService;
#Override
public JSONObject call() throws Exception {
....
//Upload image via `imageUploadService`
imageUploadService.getService().path('...').post('...'); // Getting null pointer here for imageUploadService which is a WebTarget
}
}
The ImageUploadService looks like the below,
#Component
public class ImageUploadService {
#Inject
#EndPoint(name="imageservice") //Custom annotation, battle tested and works well for all other services
private WebTarget imageservice;
public WebTarget getService() {
return imageservice;
}
}
Here is the spring boot application class,
#ComponentScan
#EnableSpringConfigured
#EnableLoadTimeWeaving(aspectjWeaving=EnableLoadTimeWeaving.AspectJWeaving.ENABLED)
#EnableAutoConfiguration
public class ImageApplication extends SpringBootServletInitializer {
#Bean
public InstrumentationLoadTimeWeaver loadTimeWeaver() throws Throwable {
InstrumentationLoadTimeWeaver loadTimeWeaver = new InstrumentationLoadTimeWeaver();
return loadTimeWeaver;
}
#Override
public void onStartup(ServletContext servletContext) throws ServletException {
super.onStartup(servletContext);
servletContext.addListener(new RequestContextListener());
}
public static void main(String[] args) throws IOException {
SpringApplication.run(ImageApplication.class);
}
}
Additional information :
Spring version of dependencies are at 4.2.5.RELEASE
pom.xml has dependencies added for spring-aspects and
spring-instrument
I am getting a NullPointerException in ImageUploadTask. My suspicion is that #Autowired doesn't work as expected.
Why wouldn't work and how do I fix this?
Is it mandatory to use #Autowired only when I use #Conigurable, why not use #Inject? (though I tried it and getting same NPE)
By default the autowiring for the #Configurable is off i.e. Autowire.NO beacuse of which the imageUploadService is null
Thus update the code to explicity enable it either as BY_NAME or BY_TYPE as below.
#Component
#Configurable(preConstruction = true, autowire = Autowire.BY_NAME)
#Scope(BeanDefinition.SCOPE_PROTOTYPE)
public class ImageUploadTask implements Callable<JSONObject> { .... }
Rest of the configuration viz. enabling load time weaving seems fine.
Also regarding #Inject annotation have a look here which pretty much explains the difference (or similarity perhaps)
I have defined a service in Spring
#Service("StockageService")
public class StockageServiceImpl implements StockageService{
}
with
public interface StockageService extends Serializable {
}
And I need in a servlet to invoke this service
So I wrote
public class SpringApplicationContextListener implements ServletContextListener {
#Override
public void contextInitialized(ServletContextEvent sce) {
ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext.xml");
sce.getServletContext().setAttribute("applicationContext", ac);
}
public void contextDestroyed(ServletContextEvent sce) {
throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
}
}
And
public class handler extends HttpServlet {
private String message;
private StockageService stockageService;
#Override
public void init(ServletConfig config) throws ServletException {
super.init(config);
ApplicationContext ac = (ApplicationContext) config.getServletContext().getAttribute("applicationContext");
this.stockageService = (StockageService)ac.getBean("StockageService");
}
The problem is that I get a NPE at the last mentionned line
(StockageService)ac.getBean("StockageService");
Where could I have made a mistake ?
First, thanks ankur-singhal for having taken the time to answer my question
I understand the reasonnement of your answer but it does not work when I invoke
ApplicationContextUtils. getApplicationContext().getBean("StockageService");
So I used a trick which works but I do not understand very well
I override the init in my servlet as it follows
#Override
public void init(ServletConfig config) throws ServletException {
super.init(config);
SpringBeanAutowiringSupport.processInjectionBasedOnServletContext(this,
config.getServletContext());
}
and I have to put a
#Autowired
private StockageService stockageService;
in the servlet and it works
It seems that ApplicationContext itself is comming as null.
Look at below code and try make use of this.
ApplicationContextUtils.java
We will create the following utility class, it implements ApplicationContextAware and provides the setApplicationContext which will be invoked by spring container and the applicationContext will be passed by it. We store it in a static variable and expose it through a get method so that it can be accessed all through the application.
You can set the same while creating ApplicationContext
import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
public class ApplicationContextUtils implements ApplicationContextAware {
private static ApplicationContext ctx;
#Override
public void setApplicationContext(ApplicationContext appContext)
throws BeansException {
ctx = appContext;
}
public static ApplicationContext getApplicationContext() {
return ctx;
}
}
For static analysis of my Spring config, I need just the bean definitions - actually creating the beans would cause problems because some need a (properly initialized) database.
Is there a way to prevent the AnnotationConfigApplicationContext to create any beans? Instead, it should just load and analyze the config and stop.
you could implement the BeanDefinitionRegistryPostProcessor interface. in the postProcessBeanDefinitionRegistry method you have access to BeanDefinition's
public class MyBeanDefinitionRegistryPostProcessor implements BeanDefinitionRegistryPostProcessor {
#Override
public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
// ...
}
#Override
public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {
registry.getBeanDefinition("myBean");
}
}