I have Spring bean with annotations:
#Named
#Scope("session")
And this bean property:
#Autowired
ApplicationContext appContext;
The Spring configuration file has entry (that works for other anotations/injections):
<context:component-scan base-package="my.package.name" />
Why appContext is null after such code and configuration?
I am trying to get ApplicationContext (to call getBean(...) on it) and this can be quite involved task (judging from other discussions) in previous Spring versions (e.g. one is required to get ServletContext in Spring web application to create ApplicationContext and getting ServletContext can be quite involved task for beans that don't directly access HTTP Request objects). In Spring 3.x, as I understand, simple #Autwired injection can be used. How AppContext can be accessed?
Here the first problem is you are using #Named which is Java EE annotation and as for as I know Spring yet to support Java EE annotations. Hence instead of using #Named try to use Spring annotation #Service, #Component, #Repository etc.
Here is the example for you I have used JSF Managed bean as well to show how to integrate beans.
#ManagedBean(name="myBacking")
#RequestScoped
public class MyBacking {
private String myText;
#ManagedProperty(value="#{mySpring}")
MySpringBean mySpring;
public String getMyText() {
myText = mySpring.getText();
return myText;
}
public void setMyText(String myText) {
this.myText = myText;
}
public MySpringBean getMySpring() {
return mySpring;
}
public void setMySpring(MySpringBean mySpring) {
this.mySpring = mySpring;
}
}
#Service("mySpring")
#Scope("request")
public class MySpringBean {
#Autowired
MySecond mySecond;
public String getText(){
return "Hello KP" + mySecond.appObj();
}
}
#Service
#Scope("request")
public class MySecond {
#Autowired
ApplicationContext applicationContext;
public String appObj(){
MyThrid mythird =(MyThrid)applicationContext.getBean("myThrid");
return "My Second Bean calld "+ mythird.getTxt();
}
}
#Service
public class MyThrid {
public String getTxt(){
return "from thrid Bean";
}
}
Related
Is it possible to wire a Spring Managed Bean into a class which is not
managed by Spring IoC?
Let's say there are two classes ClassA (not managed by spring) and
ClassB (managed by Spring) is it possible to wire ClassB in ClassA.
This was a recent question I came across and I had no clue how to do it?
Yes It is possible. You'll need an ApplicationContextAware implementation for getting the Spring Managed Bean instance using the ApplicationContext. It's an old Spring Framework trick.
import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;
#Component
public final class BeanUtil implements ApplicationContextAware {
private static ApplicationContext CONTEXT;
#Override
public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
CONTEXT = applicationContext;
}
public static <T> T getBean(Class<T> beanClass) {
return CONTEXT.getBean(beanClass);
}
}
Then you must use BeanUtil::getBean static method in ClassA to get the ClassB instance within the ApplicationContext.
public class ClassA {
private ClassB classB;
#Override
public String toString() {
return "ClassA - " + getClassB().toString();
}
// Lazy initialization of ClassB to avoid NullPointerException
private ClassB getClassB() {
if (classB == null) {
classB = BeanUtil.getBean(ClassB.class);
}
return classB;
}
}
Forget about "wiring" if Spring is not managing the bean.
Instead,
just solve the problem of "How do I get a reference to a managed bean into a non-managed bean".
In your example,
since ClassA is not managed by Spring you must be creating it somewhere.
Pass a reference to ClassB to ClassA when you create the instance of ClassA.
When i try to run a spring boot project, it tolde me that it can not autowire some beans whitch are instanciated in a configuration classes.
I think that spring can not load those configuration classes in order.
The stack trace : no bean found the be autowired Ignite<Long,MyEntity> myEntityCache in MyDao
Here is the source :
The main class
#SpringBootApplication
// The beans in the IgniteConfig have to be loaded before dao, service, and Controller
#ComponentScan(basePackageClasses={IgniteConfig.class,AppConfig.class})
public class DemoIgnite {
public static void main(String[] args) {
SpringApplication.run(DemoIgnite .class, args);
}
}
Config Class 1
#Configuration
public class IgniteConfig {
#Bean
public SpringContext springContext() {
return new SpringContext();
}
#Bean
public Ignite igniteInstance(#Autowired SpringContext springContext) {
IgniteConfiguration cfg = new IgniteConfiguration();
cfg.setIgniteInstanceName("instance");
List<CacheConfiguration> ccDas = new ArrayList<>();
CacheConfiguration cch = new CacheConfiguration<>("myEntitycache");
cch.setCacheMode(CacheMode.REPLICATED);
cch.setIndexedTypes(Long.class, myEntity.class);
ccDas.add(cch);
cfg.setCacheConfiguration( ccDas.toArray(new CacheConfiguration[0]));
SpringCacheManager springCacheManager = new SpringCacheManager();
springCacheManager.setConfiguration(cfg);
return Ignition.start(cfg);
}
#Bean
public IgniteCache<Long, MyEntity> myEntityCache(#Autowired Ignite igniteInstance) {
return igniteInstance.cache("myEntitycache");
}
Config class 2
#Configuration
#ComponentScan({
"com.demo.repository",
"com.demo.service",
"com.demo.controller"
})
public class AppConfig {
}
Dao class
#Repository
public class MyDao{
#Autowired
private Ignite<Long,MyEntity> myEntityCache;
...
Service class:
#Service
public class MyService{
#Autowird
private MyDao dao;
...
Controller class:
#RestController
#RequestMapping
public class MyController{
#Autowired
private MyService service;
....
This means that you don't have a bean of Ignite<Long,MyEntity> type in your context. Moreover springContext bean seems redundant, it's not used by igniteInstance bean. As pointed out by moilejter it probably should be:
IgniteConfig
#Bean
public Ignite ignite() {
...
}
#Bean
public IgniteCache<Long, MyEntity> myEntityCache() {
return ignite().cache("myEntitycache");
}
MyDao
#Repository
public class MyDao {
#Autowired
private IgniteCache<Long, MyEntity> myEntityCache;
...
}
In principle Spring performs the bean setup in few phases as explained in chapter 1.3.2. Instantiating Beans docs:
Bean definition discovery - resources like #Configuration classes or XML files are scanned and bean signatures are collected.
Eager beans instantiation e.g. singletons - from the definitions collected in point 1 while resolving dependencies between definitions. That's why there is no explicit bean instantiation order as the process is driven from dependencies.
Lazy beans instantiation e.g. #Lazy annotated - when the context is already up, this beans will be constructed only when accessed from code.
I am working on one component to achieve audit using Spring AOP. I could use it for most of the service's methods. But found that with Mybatis mappers AOP point-cuts don't work.
Basically, Spring AOP only works with Spring-managed beans. But these mapper beans have been scanned using mybatis.spring.*.MapperScan and can be autowired in other Spring components.
Why can these beans not be scanned for Spring AOP? Any idea?
I can use AspectJ but was keen to find out how mybatis.spring.*.MapperScan works.
for example -
I have these configurations one for Mybatis mapper scan and other config for application specific configurations.
#Configuration
#MapperScan("com.test.mapper")
public class ProviderConfiguration {
#Bean
public SqlSessionFactory sqlSessionFactory(final DataSource src) throws Exception {
...
}
}
#Configuration
#EnableAspectJAutoProxy
public class MainConfiguration {
}
My Dao logic where i call mapper method -
#Component
public class TestDao {
//injecting mybatis mapper here
#Inject
private SaveTableData saveTableData;
public TableData save(TableData tableData) {
saveTableData.updateTableData(tableData);
}
}
I have registered my pointcuts as below
#Component
#Aspect
public class TestAdvices {
#Pointcut("execution(* com.test.mapper.SaveTableData.updateTableData(*))")
public void commonSaveTableData(TableData tableData) {
}
#Pointcut("execution(* com.test.service.CreateTableData.createTableData(*))")
public void commonCreateTableData(TableData tableData) {
}
//advices
#After("commonSaveTableData(tableData)")
public void addHistoryWhenSaveTableData(TableData tableData) throws Throwable {
//do stuff
}
//advices
#After("commonCreateTableData(tableData)")
public void addHistoryWhenCreateTableData(TableData tableData) throws Throwable {
//do stuff
}
}
Issue is commonCreateTableData which is on service method works as expected. But commonSaveTableData which is on Mybatis mapper method does't get invoke.
Question is if i can autowire these Mappers in any Spring bean why can't Spring AOP intercept method call using these pointcuts?
I think your pointcut expression is not correct, try this
#Component
#Aspect
public class TestAdvices {
#Pointcut("execution(* com.test.mapper.SaveTableData.updateTableData(*)) && args(tableData)", argNames="tableData")
public void commonSaveTableData(TableData tableData) {
}
//advices
#After("commonSaveTableData(tableData)", argNames="tableData")
public void addHistoryWhenSaveTableData(TableData tableData) throws Throwable {
//do stuff
}
//...
}
The reason you can't cut into the mapper like this is that when mapper is scanned by mybatis, it's bean definition has bean changed in a way that its interface is still the mapper interface but its class has been changed to MapperFactoryBean
I am creating a custom AutoConfiguration for Spring Boot. One of the features I was attempting to create was to create one or more Beans dynamically and adding them to the ApplicationContext at runtime.
The problem I ran into was with Autowiring. My #SpringBootApplication class autowires those beans, and since they do not exist yet, autowire fails.
My first solution was to put #Lazy on the autowire, and that solved my problem.
However, I ran into something interesting. I added two beans that I was looking for into the AutoConfiguration code, and of course, it worked. By accident, I only removed one of the beans and re-ran my code. It worked.
#SpringBootApplication
public class SpringBootDemoApplication {
#Autowired
#Qualifier("some_name")
private MyClass myClass;
#Autowired
#Qualifier("another_name")
private MyClass anotherClass;
...
}
#Configuration
public class MyAutoConfigurationClass {
#Bean(name="some_class")
public MyClass myClass () {
return null;
}
}
So the short of it is this. If I defined only one of the beans in my autoconfiguration class, this seems to satisfy Autowired and it does not blow up and when I dynamically add my other beans, both beans are found.
The stipulation is that the Autowired bean that is first, must be the bean that is defined in my autoconfiguration class.
I am running the following:
Spring Boot Starter 1.5.7-RELEASE
Various Spring Framework 4.3.11-RELEASE
Is this a bug? Or is this the way Autowired is supposed to work?
#SpringBootApplication
public class SpringBootDemoApplication {
#Autowired
#Qualifier("myclass")
private MyClass myClass;
#Autowired
#Qualifier("anotherMyClass")
private MyClass anotherMyClass;
...
}
#Configuration
public class MyAutoConfiguration {
private ConfigurableApplicationContext applicationContext;
private final BeanFactory beanFactory;
#Autowired
private MyClassFactory myClassFactory;
public MyAutoConfiguration(ApplicationContext applicationContext, BeanFactory beanFactory) {
this.beanFactory = beanFactory;
this.applicationContext = (ConfigurableApplicationContext) applicationContext;
}
#PostConstruct
public void init() throws IOException, SQLException {
this.myClassFactory.create(this.applicationContext);
}
// without this #Bean definition SpringBoot will recieve the following error and stop
// AnnotationConfigEmbeddedWebApplicationContext - Exception encountered during context initialization
#Bean(name="myClass")
public DataSource anyNameWillDoItDoesntMatter() {
return null;
};
}
#Component
class MyClassFactory {
public void create(ConfigurableApplicationContext applicationContext) {
applicationContext.getBeanFactory().registerSingleton(name, value);
}
}
So is this expected behavior of #Autowired?
I wonder if there is a way to get #Required working when doing the configuration by annotations. I turned my configuration up-and-down and back again but nothing seems to work for me. I'm using Spring 3.1
My basic configuration looks like this:
#Configuration
public class SpringConfig {
#Bean
public MailSender mailSender() {
MailSender MailSender = new MailSender();
// mailSender.setBean(dlMailSender);
return mailSender;
}
#Bean
public MyBean myBean() {
MyBean myBean = new MyBean();
// setting som props
return myBean;
}
}
MailSender is here:
#Configurable
public class MailSender {
private MyBean myBean;
#Required
public void setMyBean(MyBean myBean) {
this.myBean = myBean;
}
}
I'm testing it with this junit:
#RunWith(SpringJUnit4ClassRunner.class)
#ContextConfiguration(classes = { SpringConfig.class }, loader = AnnotationConfigContextLoader.class)
public class MailSenderTest {
#Test
public void test_main_beans_exists() {
// when then given
}
}
Thanks for any help
Short answer - this is not even theoretically possible.
When using XML-based, bean definitions with their dependencies are completely managed by application context. Spring is able to check, what is being set and what is not being set.
When using annotation-based configuration, you are setting the dependencies yourself. There is no way how Spring can even know what you are doing with the bean before returning it from the factory method.
If you want to check whether the bean is correctly initialized, use InitializingBean or #PostConstruct and implement self-checking method. Spring is doing this regularly in its own beans.