What is the equivalent of Guice's #ImplementedBy annotation in Spring DI? (I googled it but with no results.)
There is not exist JIT default binding in Spring. You can set only one implementation to dependency or use naming qualifier #Named or #Qualifier annotation to specify implementation but this is static binding (not equivalent to #ImplementedBy Guice implementation).
I created a spring extension enabling the jit-binding. this library add #ImplementedBy annotation to Spring. See https://github.com/devacfr/spring-implementedby and give me feedback
You can use the annotation #Qualifier
http://static.springsource.org/spring-framework/docs/3.2.0.M2/api/org/springframework/beans/factory/annotation/Qualifier.html
Related
From documentation Spring Boot uses ConcurrentMapCacheManager as CacheManager implementation by default if we don't define own CacheManager bean definition. But I keep getting 'No qualifying bean of type 'org.springframework.cache.CacheManager' available' error eventhough spring-boot-starter-cache and #EnableCaching is there.
Any help would be greatly appreciated.
Best regards,
SetNug
Short answer... NO.
I suspect you are having problems while (integration) testing? If so, then you probably need to declare the appropriate "test slice annotation", that is #AutoConfigureCache; see Javadoc.
To demonstrate, I created a simple example with a test class contained in this module of my SO repository. You must declare the #AutoConfigureCache annotation in configuration (see here) even if your test is a #SpringBootTest.
As Spring Boot's documentation describes, all of Spring Boot's auto-configuration (which is quite extensive) can be a bit much for testing. As such, none of Spring Boot's auto-configuration is enabled by default. Therefore, you must explicitly enable what you want, or, alternatively, you can declare that you want Spring Boot's entire auto-configuration enabled, by replacing the #AutoConfigureCache annotation declaration with Spring Boot's #EnableAutoConfiguration annotation instead.
You are correct that Spring Boot will auto-configure a "Simple" caching provider (i.e. the ConcurrentMapCacheManager, or in other words, a Spring CacheManager implementation backed by a java.util.concurent.ConcurrentHashMap; see here) when no other cache provider implementation (e.g Redis) is present or explicitly declared.
However, Spring Boot auto-configuration is only in effect when your Spring Boot application is an "application", which I have shown here.
Of course, it is also true that if your #SpringBootApplication annotated class is found (in the classpath component-scan) by your test as described, then it will also enable caching without any explicit annotations, such as, no need to explicitly declare the #AutoConfigureCache test slice annotation, even.
NOTE: In my example, I deliberately did not package the source according to the suggested structure. So, if I were to replace the #AutoConfigureCache annotation declaration in my test configuration with #Import(SpringBootDefaultCachingApplication.class) and comment out this assertion from the application class, then the test would also pass. Using the #Import annotation in this way works similarly as if the test class and application class were in the same package, or the application class were in a parent package relative to the test class.
1 last tip... you can always enable Spring Boot debugging (see Baeldung's blog) to see what auto-configuration is applied while running your application, or even while running tests.
I downloaded the spring-framework project, because I want to see how #Autowired is implemented.
So, I got to this file, which is an interface.
But when I want in Intellij to go to its implementation, no implementations are found.
So is this interface not implemented?
Then where is the code for #Autowired?
Well, this is not an interface it is actually an annotation.
In java #inteface is used to create an annotation.
Once the annotation is created, you can use that annotation on fields, classes, methods (based on what is specified in #Target of the annotation definition.
Spring does package scanning and finds all the things which are using a particular annotation and does the required processing.
Use this article to undestand more in How an annotation is created, used and the how the annotation processor finds and processes the annotation.
#Autowired doesn't really have much code, so to speak. It's just an annotation which is a Java type of interface that provides instructions to other parts of the codebase.
#Autowired is only an annotation or you can say a "marker". Spring use reflection to identify annotation and do something about that annotated thing. For example with #Autowired, when spring found it, spring will inject the annotated property with eligible bean.
I seems have problem understanding these 2 annotation. I have try to read the javadocs but still cannot figure out. Can anyone help to explain with simple code about these 2 ?
Thank so much in advance.
You use #Configuration as a replacement to the XML based configuration for configuring spring beans. So instead of an xml file we write a class and annotate that with #Configuration and define the beans in it using #Bean annotation on the methods.
And finally you use AnnotationConfigApplicationContext to register this #Configuration class and thus spring manages the beans defined. Small example you can find at Spring Configuration Documentaion.
Quoting from the above link
It is just another way of configuration Indicates that a class declares
one or more #Bean methods and may be processed by the Spring container
to generate bean definitions and service requests for those beans at
runtime.
And #Configurable is an annotation that injects dependencies into objects that are not managed by Spring using aspectj libraries. i.e., you still use old way of instantiation with plain new operator to create objects but the spring will take care of injecting the dependencies into that object automatically for you.
#Configuration is the heart of the Java-based configuration mechanism and provides an alternative to XML-based configuration.
#Configuration classes are just like regular #Components classes, except that methods annotated with #Bean are used to factory beans.
In struts2 i almost did not use any xml configs and used much of annotations for MVC. I build a small application in that way using struts2. Now i want to develop same project using spring 3.2. Now i want to use annotation to create beans and request mapping (this i used). I want a clear example of using bean annotations and is it possible to set properties using annotations. I am getting confused because the documentation is too large, and many annotations. providing a simple list of annotations and their usage with simple example will be a great help.
Iam doing sample project on Spring 3.1.
I have used some annotations to create beans.Below are the annotations i have used.
#Component - Annotation used to create a bean given by Spring
#Resource,#Bean
JSR Annotations: #Controller,#Repository, #Service
If you are annotating your class with above annotations Spring Container will create beans for you.
Your properties will be set with help of #Autowired annotation.
I've got an application which uses JAXRS to map Restlet resources using annotations. However, the only entry point I have is essentially defining a list of resource classes in the application configuration. These classes are instantiated by Restlet or JAXRS, so I have no way to put them in my ApplicationContext. Is there a way to have Spring scan the classpath and autowire new instances as necessary? I've already tried using something like below:
#Autowired
private SessionFactory sessionFactory;
Unfortunately, it doesn't really work. Is there a way to do what I'm talking about here?
You can use AspectJ to dependency inject your beans that are created out of your control, or if you create objects using new. You can read more on Springs documentation: http://static.springsource.org/spring/docs/3.0.x/spring-framework-reference/html/aop.html#aop-using-aspectj
Essentially what you will do is add #Configurable annotation to the class that you want to be target of injection. You also have to enable it in Spring by having in your Spring xml. Lastly you have to decide between compile time weaving or runtime weaving. Again you can get help from spring documentation.
Loadtime weaving: http://static.springsource.org/spring/docs/3.0.x/spring-framework-reference/html/aop.html#aop-aj-ltw
If you use maven you can check this Stackoverflow question for setting up compile time AspectJ: Why doesn't AspectJ compile-time weaving of Spring's #Configurable work?
ApplicationContext.getAutowireCapableBeanFactory().autowireBean(object) will inject all dependencies into the object.