Spring_CoreTechnologies_eng

Transcript

1. Spring Core Technologies Alexander Akoemov
2. Architecture March 2016, Spring Core Technologies Talk, Alexander Akoemov 2
3. Core Container March 2016, Spring Core Technologies Talk, Alexander Akoemov 3 Core Container : - Core – base classes for Framework - Bean – BeanFactory implementation factory pattern. - Context – construct structure based on Core and Beans, ApplicationContext interface is one of the basic module. - Expression Language – to query and modify objects in the runtime
4. IoC Containers March 2016, Spring Core Technologies Talk, Alexander Akoemov 4 Spring IoC Containers - base Spring Framework. The container will create objects, connect them together, set them up, and manages their lifecycle, from creation to destruction. IoC uses dependency injection (DI) for controlling the components that comprise the application. Such objects are called Spring Beans. The container receives its instructions to create instances of objects, configuration and assembly by reading configuration. Configuration Types: • XML • Java аннотации • Java код • Groovy.
5. IoC Containers Types March 2016, Spring Core Technologies Talk, Alexander Akoemov 5 1) Spring BeanFactory Container - This is the simplest implementation of the container, the base support and DI determined org.springframework.beans.factory.BeanFactory interface. BeanFactory and related interfaces, such as BeanFactoryAware, InitializingBean, DisposableBean. 2) Spring ApplicationContext Container - The container adds more enterprise features such as the ability to handle the propertyfile. This container is determined org.springframework.context.ApplicationContext interface. ApplicationContext container includes a container BeanFactory all functionalcapabilities.
6. BeanFactory Container March 2016, Spring Core Technologies Talk, Alexander Akoemov 6 public class HelloWorld { private String message; public void setMessage(String message) { this.message = message; } public void getMessage() { System.out.println("Your Message : " + message); } } public class MainApp { public static void main(String[] args) { XmlBeanFactory factory = new XmlBeanFactory( new ClassPathResource("Beans.xml")); HelloWorld obj = (HelloWorld) factory.getBean("helloWorld"); obj.getMessage(); } }
7. ApplicationContext Container March 2016, Spring Core Technologies Talk, Alexander Akoemov 7 import org.springframework.context.ApplicationContext; import org.springframework.context.support.FileSystemXmlApplicationContext; public class MainApp { public static void main(String[] args) { ApplicationContext context = new FileSystemXmlApplicationContext("C:/src/Beans.xml"); HelloWorld obj = (HelloWorld) context.getBean("helloWorld"); obj.getMessage(); } }
8. Dependency Injection(DI) March 2016, Spring Core Technologies Talk, Alexander Akoemov 8 • Constructor-based dependency injection public class ConstructorTypeDIBean { private ServiceBean serviceBean; // constructor to inject the dependency public ConstructorTypeDIBean(ServiceBean serviceBean) { this.serviceBean = serviceBean; } public void useService() { System.out.println("ConstructorTypeDIBean:" + erviceBean.action()); } }
9. Dependency Injection(DI) March 2016, Spring Core Technologies Talk, Alexander Akoemov 9 • Setter-based dependency injection public class SetterTypeDIBean { private ServiceBean serviceBean; // a setter method to inject the dependency. public void setServiceBean(ServiceBean serviceBean) { this.serviceBean = serviceBean; } public void useService() { System.out.println("SetterTypeDIBean:" + serviceBean.action()); } }
10. Bean Definition March 2016, Spring Core Technologies Talk, Alexander Akoemov 10 Properties Description class This attribute is mandatory and specify the bean class to be used to create the bean. name This attribute specifies the bean identifier uniquely. In XML-based configuration metadata, you use the id and/or name attributes to specify the bean identifier(s). scope This attribute specifies the scope of the objects created from a particular bean definition and it will be discussed in bean scopes chapter. constructor-arg This is used to inject the dependencies and will be discussed in next chapters. properties This is used to inject the dependencies and will be discussed in next chapters. autowiring mode This is used to inject the dependencies and will be discussed in next chapters. lazy-initialization mode A lazy-initialized bean tells the IoC container to create a bean instance when it is first requested, rather than at startup. initialization method A callback to be called just after all necessary properties on the bean have been set by the container. It will be discussed in bean life cycle chapter. destruction method A callback to be used when the container containing the bean is destroyed. It will be discussed in bean life cycle chapter.
11. Bean Definition March 2016, Spring Core Technologies Talk, Alexander Akoemov 11 <?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd"> <!-- A simple bean definition --> <bean id="..." class="..."> <!-- collaborators and configuration for this bean go here --> </bean> <!-- A bean definition with lazy init set on --> <bean id="..." class="..." lazy-init="true"> <!-- collaborators and configuration for this bean go here --> </bean> <!-- A bean definition with initialization method --> <bean id="..." class="..." init-method="..."> <!-- collaborators and configuration for this bean go here --> </bean> <!-- A bean definition with destruction method --> <bean id="..." class="..." destroy-method="..."> <!-- collaborators and configuration for this bean go here --> </bean> <!-- more bean definitions go here --> </beans>
12. Java Based Configuration March 2016, Spring Core Technologies Talk, Alexander Akoemov 12 import org.springframework.context.annotation.*; @Configuration public class HelloWorldConfig { @Bean public HelloWorld helloWorld(){ return new HelloWorld(); } } HelloWorldConfig.java HelloWorld.java public class HelloWorld { private String message; public void setMessage(String message){ this.message = message; } public void getMessage(){ System.out.println("Your Message : " + message); } }
13. Java Based Configuration March 2016, Spring Core Technologies Talk, Alexander Akoemov 13 MainApp.java import org.springframework.context.ApplicationContext; import org.springframework.context.annotation.*; public class MainApp { public static void main(String[] args) { ApplicationContext ctx = new AnnotationConfigApplicationContext(HelloWorldConfig.class); HelloWorld helloWorld = ctx.getBean(HelloWorld.class); helloWorld.setMessage("Hello World!"); helloWorld.getMessage(); } }
14. Bean Scopes March 2016, Spring Core Technologies Talk, Alexander Akoemov 14 • singleton - This scopes the bean definition to a single instance per Spring IoC container (default). • prototype - This scopes a single bean definition to have any number of object instances. • request - This scopes a bean definition to an HTTP request. Only valid in the context of a web-aware Spring ApplicationContext. • session - This scopes a bean definition to an HTTP session. Only valid in the context of a web-aware Spring ApplicationContext. • global-session - This scopes a bean definition to a global HTTP session. Only valid in the context of a web-aware Spring ApplicationContext. <!-- A bean definition with singleton scope --> <bean id="..." class="..." scope="singleton"> <!-- collaborators and configuration for this bean go here --> </bean>
15. Autowiring March 2016, Spring Core Technologies Talk, Alexander Akoemov 15 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 asetMaster(..) 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. autodetect – means chooses “autowire by constructor” if default constructor (argument with any data type), otherwise uses “autowire by type“.
16. Autowiring March 2016, Spring Core Technologies Talk, Alexander Akoemov 16 import org.springframework.beans.factory.annotation.Autowired; import org.springframework.beans.factory.annotation.Qualifier; public class Profile { @Autowired @Qualifier("student1") private Student student; public Profile() { System.out.println("Inside Profile constructor."); } public void printAge() { System.out.println("Age : " + student.getAge()); } public void printName() { System.out.println("Name : " + student.getName()); } } @Autowired The @Autowired annotation can apply to bean property setter methods, non-setter methods, constructor and properties
17. @Import Annotation March 2016, Spring Core Technologies Talk, Alexander Akoemov 17 @Configuration @Import(ConfigA.class) public class ConfigB { @Bean public B b() { return new B(); } } @Configuration public class ConfigA { @Bean public A a() { return new A(); } } public static void main(String[]args){ ApplicationContext ctx = new AnnotationConfigApplicationContext(ConfigB.class); // now both beans A and B will be available... A a=ctx.getBean(A.class); B b=ctx.getBean(B.class); } класс ConfigA класс ConfigB ApplicationContext
18. Bean Life Cycle March 2016, Spring Core Technologies Talk, Alexander Akoemov 18
19. Bean Post Processors March 2016, Spring Core Technologies Talk, Alexander Akoemov 19 public class HelloWorld { private String message; public void setMessage(String message){ this.message = message; } public void getMessage(){ System.out.println("Your Message : " + message); } public void init(){ System.out.println("Bean is going through init."); } public void destroy(){ System.out.println("Bean will destroy now."); } }
20. Bean Post Processors March 2016, Spring Core Technologies Talk, Alexander Akoemov 20 import org.springframework.beans.factory.config.BeanPostProcessor; import org.springframework.beans.BeansException; public class InitHelloWorld implements BeanPostProcessor { public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException { System.out.println("BeforeInitialization : " + beanName); return bean; // you can return any other object as well } public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException { System.out.println("AfterInitialization : " + beanName); return bean; // you can return any other object as well } } BeforeInitialization : helloWorld Bean is going through init. AfterInitialization : helloWorld Your Message : Hello World! Bean will destroy now.
21. Sources and Resources March 2016, Spring Core Technologies Talk, Alexander Akoemov 21 http://docs.spring.io/spring/docs/current/spring-framework- reference/htmlsingle/#spring-core http://www.tutorialspoint.com/spring Pro Spring, 4th Edition Author: Chris Schaefer , Clarence Ho , Rob Harrop Примеры: https://github.com/akoemov/Spring_CoreTechnologies
22. Questions are welcome! March 2016, Spring Core Technologies Talk, Alexander Akoemov 22 Alexander Akoemov email: akoemov@gmail.com Linkedin: www.linkedin.com/in/akoemov GitHub: github.com/akoemov Skype: akoemov
23. Thank you for your attention! March 2016, Spring Core Technologies Talk, Alexander Akoemov 23