Examples of Spring combination annotation and meta annotation in JSP, jspspring

Examples of Spring combination annotation and meta annotation in JSP, jspspring

Spring combination annotation and Metadata Annotation instances in JSP

Abstract: Annotation is also called metadata. A code-level description. It is at the same level as classes, interfaces, and enumeration. It can be declared before packages, classes, fields, methods, local variables, and method parameters to describe these elements.

1. annotations that can be annotated to other annotations are called meta annotations, and annotations are called combination annotations. Through combination annotations, You can simplify a lot of repetitive annotation operations.

2. Combined annotation of examples

import org.springframework.context.annotation.ComponentScan;import org.springframework.context.annotation.Configuration;import java.lang.annotation.*;@Target(ElementType.TYPE)@Retention(RetentionPolicy.RUNTIME)@Documented@Configuration@ComponentScanpublic @interface GroupAnnotation {  String[] value() default {};}

Code explanation: Combine @ Configuration and @ ComponentScan meta annotation, and overwrite the value Parameter

3. Compile common Bean

@ Servicepublic class DemoService {public void sys () {System. out. println ("Comments sample ");}}

4. Configuration classes using composite annotations

@GroupAnnotation("com.xuanwu.annotation")public class DemoConfig {}

5. Run

public class Main {  public static void main(String[] args) {   AnnotationConfigApplicationContext context = new      AnnotationConfigApplicationContext(DemoConfig.class);   DemoService demoService = context.getBean(DemoService.class);   demoService.sys();  }}

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