Spring learns the definition of bean with the configuration of nine----------Bean and the annotation implementation of its scope

Common annotations for Spring beans

@Component: usually annotations, available for any bean

@Repository: Typically used to annotate the DAO layer, which is the persistence layer

@Service: Typically used to annotate service tiers, or services tiers

@Controller: Typically used to annotate the controller layer, which is the control layer

Automatic detection of classes and the registration of beans

<context:component-scan base-package= ""/>: Automatically scans for classes under Base-package defined packages or their sub-packages, and will have @component, @Controller, @Service , the classes of annotations such as @Repository are automatically registered in the IOC container.

<CONTEXT:ANNOTATION-CONFIG/>: Implicitly registers the autowiredannotationbeanpostprocessor with the spring container, Commonannotationbeanpostprocessor, Persistenceannotationbeanpostprocessor and Requiredannotationbeanpostprocessor These four beanpostprocessor.

<context:component-scan/> contains <context:annotation-config/>, so use <context:component-scan/> will not be used <context:annotation-config/>

Defining beans

The bean name is generated by Beannamegenerator (@Component, @Controller, @Service, @Repository has a name property for the specified bean name to display, and the default is the class name first letter lowercase )

You can also use the Name-generator in <context:component-scan/> to customize the bean's naming policy, but implement the Beannamegenerator interface and include a parameterless constructor

Scope

@Scope annotation identifies the scope of the bean. The default is singleton.

Instance

1. Project structure

2.pom.xml

<project xmlns= "http://maven.apache.org/POM/4.0.0" xmlns:xsi= "Http://www.w3.org/2001/XMLSchema-instance" xsi: schemalocation= "http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd" ><modelversion >4.0.0</modelversion><groupid>org.spring</groupid><artifactid>spring-beanannotation </artifactid><packaging>jar</packaging><version>0.0.1-snapshot</version><name >spring-beanannotation Maven webapp</name><url>http://maven.apache.org</url><properties ><spring.version>4.3.7.RELEASE</spring.version></properties><dependencies><!-- JUnit relies on--><dependency><groupid>junit</groupid><artifactid>junit</artifactid> <version>4.12</version><scope>test</scope></dependency><!--Spring Core dependency-- <dependency> <groupId>org.springframework</groupId> <artifactid>spring-core</artifaCtid> <version>${spring.version}</version></dependency><dependency> <groupId> Org.springframework</groupid> <artifactId>spring-beans</artifactId> <version>${ Spring.version}</version></dependency><dependency> <groupid>org.springframework</ Groupid> <artifactId>spring-context</artifactId> <version>${spring.version}</version> </dependency></dependencies><build><finalName>Spring-BeanAnnotation</finalName> </build></project>

3.spring-beanannotation.xml

<?xml version= "1.0" encoding= "UTF-8"? ><beans xmlns= "Http://www.springframework.org/schema/beans"    Xmlns:xsi= "Http://www.w3.org/2001/XMLSchema-instance"    xmlns:context= "Http://www.springframework.org/schema /context "    xsi:schemalocation=" Http://www.springframework.org/schema/beans/        http Www.springframework.org/schema/beans/spring-beans.xsd        Http://www.springframework.org/schema/context        Http://www.springframework.org/schema/context/spring-context.xsd ">        <!--automatically scan the bean under the package and register it in the IOC container--    <context:component-scan base-package= "Org.spring.annotation.bean"/>    </beans>

4.beanannotation.java

Package Org.spring.annotation.bean;import Org.springframework.context.annotation.scope;import Org.springframework.stereotype.Component, @Scope ("Prototype") @Componentpublic class Beanannotation {public void Say ( {System.out.println ("Get success in annotation mode");} public void Hascode () {System.out.println ("beanannotation:" + this.hashcode ());}}

5.testbase.java

Package Org.spring.annotation.test;import Org.junit.after;import Org.junit.before;import Org.springframework.context.support.classpathxmlapplicationcontext;import org.springframework.util.StringUtils; public class Testbase {private Classpathxmlapplicationcontext context;private String xmlpath;/** * No parameter constructor */public Testbas E () {}/** * with parameter constructor, initialize profile path *  * @param xmlpath * Profile path */public testbase (String xmlpath) {this.xmlpath = Xmlpath;} /** * Initialize Spring's IOC container */@Beforepublic void before () {if (Stringutils.isempty (Xmlpath)) {//config file default path Xmlpath = "Classpath: Spring-*.xml ";} Load the config file into the spring container in context = new Classpathxmlapplicationcontext (Xmlpath.split ("[, \\s]+"));//Start IOC container Scontext.start ( );} /** * Destroy container */@Afterpublic void after () {if (context! = null) {Context.destroy ();}} /** * Gets the Bean object based on the Bean ID */public object Getbean (String ID) {return context.getbean (ID);}}

6.testbeanannotation.java

Package Org.spring.annotation.test;import Org.junit.test;import Org.spring.annotation.bean.beanannotation;public Class Testbeanannotation extends Testbase {/** * constructor incoming Spring profile path */public testbeanannotation () {Super ("Classpath: Spring-beanannotation.xml ");} /** * Test annotation method Gets the Bean object */@Testpublic void testbeanannotation () {beanannotation bean = (beanannotation) Super.getbean (" Beanannotation "); Bean.say ();} /** * The scope of the bean that tests the annotation method */@Testpublic void Testbeanscope () {beanannotation bean = (beanannotation) Super.getbean (" Beanannotation "); Bean.hascode (); Beanannotation bean2 = (beanannotation) super.getbean ("Beanannotation"); Bean2.hascode ();}}

7. Preview of effects

Reference: http://www.imooc.com/video/4030

Spring learns the definition of bean with the configuration of nine----------Bean and the annotation implementation of its scope