13Spring Configuring Beans with annotations (1)

Configuration Bean Form: XML file-based approach, annotation-based configuration bean, annotation- based assembly of Bean properties

The following describes the annotation-based approach to configuring beans.

--component scanning (component scanning): Spring is able to automatically scan, detect and instantiate components with specific annotations from the classpath.

-specific components include:

[Email protected]: basic annotations that identify a component that is managed by spring

[Email protected]: Identify the persistence layer component

[Email protected]: Identify service layer (business layer) components

[Email protected]: Identify presentation layer components

--for scanned components,Spring has a default naming policy : Use unqualified class name, first letter lowercase, or you can identify the component's name through the Value property in the annotation

After a specific annotation is used on the component class, it is also necessary to declare <context:component-scan> in the Spring configuration file (the context namespace needs to be imported):

The--base-package property specifies a base class package that needs to be scanned, and the spring container will scan all classes in the base class package and its child packages.

--When you need to scan multiple packages, you can use commas to separate

--If you want to scan only specific classes, not all classes under the base package, you can apply the Resource-pattern property to filter specific classes, for instance:

<context:component-scan base-package= "Com.spring.beans" resource-pattern= "Autowire/*.class"/>

The--<context:include-filter> child node represents the target class to be included

--<context:exclude-filter> child nodes indicate the target class to exclude

--<context:component-scan> can have a number of <context:include-filter> and <context: exclude-filter> child nodes

 Package annotation; Import org.springframework.stereotype.Component; @Component  Public class Testobject {}

 package   annotation.repository;  public  interface   Userrepository {  save ();}  

 package   annotation.repository;  import   Org.springframework.stereotype.Repository; @Repository (Value  =" Userrepository ")  public  class  userrepositoryimpl  userrepository {@Override  public  void
     Save () {System.out.println (" Userrepositoryimpl save "); }}

 package   Annotation.controller;  import   Org.springframework.stereotype.Controller; @Controller  public  class   Usercontroller { public  void   Execute () {System.out.println (" Usercontroller Execute "); }}

 Package Annotation.service; Import Org.springframework.stereotype.Service; @Service  Public class UserService {    publicvoid  Add () {        System.out.println ("UserService Add ");}    }

<?XML version= "1.0" encoding= "UTF-8"?><Beansxmlns= "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 " >    <!--Specify packages scanned by the spring IOC container -    <!--<context:component-scan base-package= "annotation" > </context:component-scan> -    <!--the scanned resource can be specified by Resource-pattern -    <!--<context:component-scan base-package= "annotation" resource-pattern= "Repository/*.class" &    Gt </context:component-scan> -    <!--Context:exclude-filter Sub-nodes specify which components to exclude from the specified expression -    <!--The context:include-filter child node Specifies the component that contains the specified expression, which needs to be use-default-filters with a -    <Context:component-scanBase-package= "Annotation">        <!--annotation Indicates whether to include or not include according to the specified annotations -        <!--<context:exclude-filter type= "annotation" expression= "Org.springframework.stereotype.Repository" ></ Context:exclude-filter> -        <!--<context:include-filter type= "annotation" expression= "Org.springframework.stereotype.Repository" ></ Context:include-filter> -        <!--assignable contains or does not contain the specified class name according to the -       <!--<context:exclude-filter type= "assignable" expression= "Annotation.repository.UserRepository" ></ Context:exclude-filter> -        <!--<context:include-filter type= "assignable" expression= "Annotation.repository.UserRepository" ></ Context:include-filter> -    </Context:component-scan></Beans>

 Packageannotation;ImportAnnotation.controller.UserController;Importannotation.repository.UserRepository;ImportAnnotation.service.UserService;ImportOrg.springframework.context.ApplicationContext;ImportOrg.springframework.context.support.ClassPathXmlApplicationContext; Public classMain { Public Static voidMain (string[] args) {ApplicationContext ctx=NewClasspathxmlapplicationcontext ("13-1.xml"); Testobject to= (testobject) ctx.getbean ("Testobject");        System.out.println (to); Usercontroller Usercontroller= (Usercontroller) ctx.getbean ("Usercontroller");        System.out.println (Usercontroller); UserService UserService= (UserService) ctx.getbean ("UserService");        System.out.println (UserService); Userrepository userrepository= (userrepository) ctx.getbean ("Userrepository");    System.out.println (userrepository); }}

13Spring Configuring Beans with annotations (1)