What are the annotations supported by the spring framework?
Due to addition of some core features from the JavaConfig project to the Spring Framework,the following annotations are now directly supported :
@Configuration
@Bean
@DependsOn
@Primary
@Lazy
@Import
@ImportResource
@Value
Explain in brief the metadata contained in the BeanDefinition objects.
Bean definitions contain the following metadata:
1. A package-qualified class name: which is the actual implementation class of the bean being defined.
2. Bean behavioral configuration elements, which state the procedure for how the bean should behave in the container
3. References to other beans that are required for the bean to do its work; these references are also called collaborators or dependencies.
4. Other configuration settings to set when a new object is created, for example, the number of connections to use in a bean that manages a connection pool or the size limit of the pool.
What are the different properties the metadata translates into to make up the bean definition?
Metadata translates into the following properties to make up:
1. Property defined in class the section called “Instantiating beans”.
2. Property defined in name the section called “Naming beans” scope constructor arguments the section known as “Dependency injection”.
3. Properties the section known as “Dependency injection” auto wiring mode the section known as “Autowiring collaborators”.
4. lazy-initialization mode the section called “Lazy-initialized beans”.
5. Initialization method the section called “Initialization callbacks”.
6. Destruction method the section called “Destruction callbacks”.
Briefly describe the 2 ways in which the class property can be used.
The class property can be put to use in the following ways:
1. It is used to specify the java bean for class to be constructed when container directly creates java bean by calling constructor reflectively. This procedure is also used for java code which uses a new operator.
2. It is also used to specify the class which contains static factory method which is invoked for creating object. Another case in this which doesn’t occur much is when static factory method is invoked by container on a class for creating the bean.
Explain the dependency resolution process.
The dependency resolution process is carried out as follows:
1. Creation an initialization of application text inside configuration metadata( can be specified in XML, java code,annotations) is done. This describes all the beans.
2. For each bean, its dependency is expressed in the form of properties, constructor arguments, or
arguments to the static-factory method if that is used instead of a normal constructor.
3. Each property or constructor argument is actual definition of the value which belong to set, or a reference to another bean which is in the container.
4. Each property or constructor argument which is a value is gone through conversion from its specified format to the actual type of that property or constructor argument.
How can you use spring to resolve collaborators for your bean? Also state the advantages of auto wiring?
The spring can be used to resolve collaborators automatically by inspecting contents of the ApplicationContext.
The Autowiring has the following advantages in spring:
1. Reduces requirement for specifying properties or construction arguments.
2. Updates configuration while evolving of objects. To understand this lets consider an example: modifying would not be required in configuration of a dependency while adding it to a class.
3. Switching to explicit wiring when code base is stable can be neglected.
List the limitations of auto wiring.
Autowiring has the following limitations :
1. Overriding and auto wiring are caused due to dependency in property and constructor argument setting.
2. Less precise as compared to explicit wiring.
3. Tools that generate documentation using a spring might not have access to wiring information.
4. There is a possibility of clash between bean definitions and argument or method to be wired.
5. The problem does not occur much in case of maps, arrays and collection and cannot be resolved randomly for dependencies which expect one value.
In scenarios where you have to avoid using auto wiring, what are the other options that can be explored to achieve the same?
In scenarios where using autowiring is prohibited, the following replacements can achive the same :
1. Abandon autowiring for favor of explicit wiring.
2. Avoid autowiring for a bean definition by setting the autowire-candidate for attributes to false as
described in the next section.
3. Set a single bean definition as the primary candidate by setting the primary attribute of its <bean/> element to true.
4. When Java 5 or later is used, implementation needs more fine-grained control available with annotation-based configuration.
How do you call the multiple life cycle mechanisms configured for the same bean?
Multiple lifecycle mechanisms which are configured for the same bean, with different initialization methods, are called by the following ways :
1. Methods annotated with use of @PostConstruct.
2. afterPropertiesSet() as stated by the InitializingBean callback interface.
3. Custom configuration init() method
Destroy methods are called in the same order as follows :
1. Methods annotated with the use of @PreDestroy.
2. destroy() as stated by the DisposableBean callback interface.
3. destroy() method with custom configuration.
What are the methods associated with the FactoryBean interface?
Following are the methods associated with factory bean interface:
1. Object getObject() : This returns an instance of the object which the factory creates. This instance can possibly be shared, depending on the factory returns singletons or prototypes.
2. Boolean isSingleton() : This returns true if this FactoryBean returns singletons, otherwise false.
3. Class getObjectType() : This returns the object type returned by the getObject() method or null if the type is unknown in advance.
What are the functionalities provided by the context package to enhance the BeanFactory functionality?
The functionalities provided by context package are as follows:
1. Message access in i18n-style, through the MessageSource interface.
2. Resource access such as URLs and files, through which, the ResourceLoader interface, can be accessed and used.
3. Publication of events, through the beans that allow, implementing the ApplicationListener interface. It is done through the use, of the ApplicationEventPublisher interface.
4. Multiple loading contexts, allowing each to be focused on one particular layer, such as the web layer of an application, through the HierarchicalBeanFactory interface.
How can you achieve Internationalization using MessageSource?
Internationnalization using message source can be achieved by the following :
1. String get Mesage(String code, Objct[] args, String default, Local loc) :
The basic method used for retrieving a message from the MessageSource. When no message is to be found for the specified locale, the default message is used.
2. String getMessage(String code, Objct[] args, Locale loc) :
Essentially the same as the last method, but with a difference, no default message is specified; if the message cannot be found, a NoSuchMessageException is shown.
3. String getMessage(MessageSourceResolvable resolvable, Local locale) :
Properties used for the preceding methods are also wrapped in a class named MessageSourceResolvable, which you can use with this method.
Enlist and explain the main methods associated with the Resource interface.
Methods associated with resource interface are as follows:
1. getInputStream() : It locates and opens the resource, returning an InputStream to read from the resource.
2. exists() : Returns a boolean which indicates whether this resource actually exists in physical form.
3. isOpen() : Returns a boolean which indicates whether this resource represents a handle with an open stream.
4. getDescription() : Returns a description for this resource, which is used for error output when working with the resource.
Due to addition of some core features from the JavaConfig project to the Spring Framework,the following annotations are now directly supported :
@Configuration
@Bean
@DependsOn
@Primary
@Lazy
@Import
@ImportResource
@Value
Explain in brief the metadata contained in the BeanDefinition objects.
Bean definitions contain the following metadata:
1. A package-qualified class name: which is the actual implementation class of the bean being defined.
2. Bean behavioral configuration elements, which state the procedure for how the bean should behave in the container
3. References to other beans that are required for the bean to do its work; these references are also called collaborators or dependencies.
4. Other configuration settings to set when a new object is created, for example, the number of connections to use in a bean that manages a connection pool or the size limit of the pool.
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| Sitel Most Frequently Asked Spring MVC Latest Interview Questions Answers |
What are the different properties the metadata translates into to make up the bean definition?
Metadata translates into the following properties to make up:
1. Property defined in class the section called “Instantiating beans”.
2. Property defined in name the section called “Naming beans” scope constructor arguments the section known as “Dependency injection”.
3. Properties the section known as “Dependency injection” auto wiring mode the section known as “Autowiring collaborators”.
4. lazy-initialization mode the section called “Lazy-initialized beans”.
5. Initialization method the section called “Initialization callbacks”.
6. Destruction method the section called “Destruction callbacks”.
Briefly describe the 2 ways in which the class property can be used.
The class property can be put to use in the following ways:
1. It is used to specify the java bean for class to be constructed when container directly creates java bean by calling constructor reflectively. This procedure is also used for java code which uses a new operator.
2. It is also used to specify the class which contains static factory method which is invoked for creating object. Another case in this which doesn’t occur much is when static factory method is invoked by container on a class for creating the bean.
Explain the dependency resolution process.
The dependency resolution process is carried out as follows:
1. Creation an initialization of application text inside configuration metadata( can be specified in XML, java code,annotations) is done. This describes all the beans.
2. For each bean, its dependency is expressed in the form of properties, constructor arguments, or
arguments to the static-factory method if that is used instead of a normal constructor.
3. Each property or constructor argument is actual definition of the value which belong to set, or a reference to another bean which is in the container.
4. Each property or constructor argument which is a value is gone through conversion from its specified format to the actual type of that property or constructor argument.
How can you use spring to resolve collaborators for your bean? Also state the advantages of auto wiring?
The spring can be used to resolve collaborators automatically by inspecting contents of the ApplicationContext.
The Autowiring has the following advantages in spring:
1. Reduces requirement for specifying properties or construction arguments.
2. Updates configuration while evolving of objects. To understand this lets consider an example: modifying would not be required in configuration of a dependency while adding it to a class.
3. Switching to explicit wiring when code base is stable can be neglected.
List the limitations of auto wiring.
Autowiring has the following limitations :
1. Overriding and auto wiring are caused due to dependency in property and constructor argument setting.
2. Less precise as compared to explicit wiring.
3. Tools that generate documentation using a spring might not have access to wiring information.
4. There is a possibility of clash between bean definitions and argument or method to be wired.
5. The problem does not occur much in case of maps, arrays and collection and cannot be resolved randomly for dependencies which expect one value.
In scenarios where you have to avoid using auto wiring, what are the other options that can be explored to achieve the same?
In scenarios where using autowiring is prohibited, the following replacements can achive the same :
1. Abandon autowiring for favor of explicit wiring.
2. Avoid autowiring for a bean definition by setting the autowire-candidate for attributes to false as
described in the next section.
3. Set a single bean definition as the primary candidate by setting the primary attribute of its <bean/> element to true.
4. When Java 5 or later is used, implementation needs more fine-grained control available with annotation-based configuration.
How do you call the multiple life cycle mechanisms configured for the same bean?
Multiple lifecycle mechanisms which are configured for the same bean, with different initialization methods, are called by the following ways :
1. Methods annotated with use of @PostConstruct.
2. afterPropertiesSet() as stated by the InitializingBean callback interface.
3. Custom configuration init() method
Destroy methods are called in the same order as follows :
1. Methods annotated with the use of @PreDestroy.
2. destroy() as stated by the DisposableBean callback interface.
3. destroy() method with custom configuration.
What are the methods associated with the FactoryBean interface?
Following are the methods associated with factory bean interface:
1. Object getObject() : This returns an instance of the object which the factory creates. This instance can possibly be shared, depending on the factory returns singletons or prototypes.
2. Boolean isSingleton() : This returns true if this FactoryBean returns singletons, otherwise false.
3. Class getObjectType() : This returns the object type returned by the getObject() method or null if the type is unknown in advance.
What are the functionalities provided by the context package to enhance the BeanFactory functionality?
The functionalities provided by context package are as follows:
1. Message access in i18n-style, through the MessageSource interface.
2. Resource access such as URLs and files, through which, the ResourceLoader interface, can be accessed and used.
3. Publication of events, through the beans that allow, implementing the ApplicationListener interface. It is done through the use, of the ApplicationEventPublisher interface.
4. Multiple loading contexts, allowing each to be focused on one particular layer, such as the web layer of an application, through the HierarchicalBeanFactory interface.
How can you achieve Internationalization using MessageSource?
Internationnalization using message source can be achieved by the following :
1. String get Mesage(String code, Objct[] args, String default, Local loc) :
The basic method used for retrieving a message from the MessageSource. When no message is to be found for the specified locale, the default message is used.
2. String getMessage(String code, Objct[] args, Locale loc) :
Essentially the same as the last method, but with a difference, no default message is specified; if the message cannot be found, a NoSuchMessageException is shown.
3. String getMessage(MessageSourceResolvable resolvable, Local locale) :
Properties used for the preceding methods are also wrapped in a class named MessageSourceResolvable, which you can use with this method.
Enlist and explain the main methods associated with the Resource interface.
Methods associated with resource interface are as follows:
1. getInputStream() : It locates and opens the resource, returning an InputStream to read from the resource.
2. exists() : Returns a boolean which indicates whether this resource actually exists in physical form.
3. isOpen() : Returns a boolean which indicates whether this resource represents a handle with an open stream.
4. getDescription() : Returns a description for this resource, which is used for error output when working with the resource.
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