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Spring from a to Z
This document provides an overview of key concepts in the Spring Framework including dependency injection, modules, beans, and annotations. It explains that Spring handles infrastructure and configuration so developers can focus on the application. It also describes concepts like the singleton scope, autowiring, AOP, and the Spring Expression Language.
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Spring from a to Z
- 1. Spring from Ato ?
- 2. Introduction to SpringFramework Spring Framework is a Java platform that provides comprehensive infrastructure support for developing Java applications. Spring handles the infrastructure so you can focus on your application.
- 3. SOLID Single responsibilityprinciple Open/closed principle Liskov Substitution Principle Interface Segregation Principle Dependency inversion principle
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- 5. Dependency Injection andInversion of Control IoC is also known as dependency injection (DI). Dependency injection (DI) is a process whereby objects define their dependencies In Spring, the objects that form the backbone of your application and that are managed by the Spring IoC container are called beans. Interface org.springframework.context.Ap plicationContext represents the Spring IoC containe
- 6. Bean overview Property Explainedin... class Ex: com.tcbs.OrderService name camel-cased from then on. Examples of such names would be (without quotes) 'accountManager','accountService', 'userDao', 'loginController' scope singleton, prototype, request, session, global session constructor arguments properties autowiring mode Name,type, constructor lazy-initialization mode ApplicationContext implementations eagerly create and configure all singleton beans as part of the initialization process initialization method destruction method
- 7. Bean scopes Scope Description singleton (Default)Scopes a single bean definition to a single object instance per Spring IoC container. prototype Scopes a single bean definition to any number of object instances. request Scopes a single bean definition to the lifecycle of a single HTTP request; that is, each HTTP request has its own instance of a bean created off the back of a single bean definition. Only valid in the context of a web- aware Spring ApplicationContext. session Scopes a single bean definition to the lifecycle of an HTTP Session. Only valid in the context of a web-aware Spring ApplicationContext. global session Scopes a single bean definition to the lifecycle of a global HTTP Session. Typically only valid when used in a portlet context. Only valid in the context of a web- aware Spring ApplicationContext.
- 8. Autowiring collaborators Mode Explanation no (Default)No autowiring. Bean references must be defined via a ref element. Changing the default setting is not recommended for larger deployments, because specifying collaborators explicitly gives greater control and clarity. To some extent, it documents the structure of a system. byName Autowiring by property name. Spring looks for a bean with the same name as the property that needs to be autowired. For example, if a bean definition is set to autowire by name, and it contains a master property (that is, it has a setMaster(..) method), Spring looks for a bean definition named master, and uses it to set the property. byType Allows a property to be autowired if exactly one bean of the property type exists in the container. If more than one exists, a fatal exception is thrown, which indicates that you may not use byType autowiring for that bean. If there are no matching beans, nothing happens; the property is not set. constructor Analogous to byType, but applies to constructor arguments. If there is not exactly one bean of the constructor argument type in the container, a fatal error is raised.
- 9. AOP Concepts Aspect– a standard code/feature that is scattered across multiple places in the application and is typically different than the actual Business Logic (for example, Transaction management). Each aspect focuses on a specific cross-cutting functionality Joinpoint – it’s a particular point during execution of programs like method execution, constructor call, or field assignment Advice – the action taken by the aspect in a specific joinpoint Pointcut – a regular expression that matches a joinpoint. Each time any join point matches a pointcut, a specified advice associated with that pointcut is executed Weaving – the process of linking aspects with targeted objects to create an advised object
- 10. Proxying mechanisms SpringAOP uses either JDK dynamic proxies or CGLIB to create the proxy for a given target object All of the interfaces implemented by the target type will be proxied. If the target object does not implement any interfaces then a CGLIB proxy will be created.
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- 13. Spring annotations @Service:Annotate all your service classes with @Service. All your business logic should be in Service classes. @Repository: Annotate all your DAO classes with @Repository. All your database access logic should be in DAO classes. @Component: Annotate your other components (for example REST resource classes) with @Component. @Autowired: Let Spring auto-wire other beans into your classes using @Autowired annotation. @Transactional: Configure your transactions with @Transactional spring annotation. @Scope: As with Spring-managed components in general, the default and most common scope for autodetected components is singleton. To change this default behavior, use @Scope spring annotation.
- 14. Spring annotations @Controller:Annotate your controller classes with @Controller. @RequestMapping: spring annotation to map URLs onto an entire class or a particular handler method. @PathVariable: spring annotation on a method argument to bind it to the value of a URI template variable. @RequestParam: You can bind request parameters to method variables using spring annotation @RequestParam. @ModelAttribute: An @ModelAttribute on a method argument indicates the argument should be retrieved from the model. @SessionAttributes: spring annotation declares session attributes. This will typically list the names of model attributes which should be transparently stored in the session, serving as form-backing beans between subsequent requests.
- 15. Spring annotations @Bean(scope=DefaultScopes.PROTOTYPE):The DefaultScopes class provides string constants for each of these four scopes. SINGLETON is the default, and can be overridden by supplying the scope attribute to @Bean annotation @Qualifier: Qualifie with the name of the specific implementation.
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Editor's Notes
- #5 https://docs.spring.io/spring/docs/3.0.x/spring-framework-reference/html/overview.html