要达到的目的:将某个包下使用了某个自定义注解(比如@MyClassMapper)的类注册到Spring 容器。
一、自定义注解:
package com.example.demo.service;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
@Retention(RetentionPolicy.RUNTIME)
public @interface MyClassMapper {
}
二、使用了自定义注解的组件类:
package com.example.demo.service;
@MyClassMapper
public class HelloService {
public HelloService(){
System.out.println("this is hello......");
}
}
三、自定义一个ClasspathBeanDefinitionScanner:
package com.example.demo.component;
import com.example.demo.service.MyClassMapper;
import com.example.demo.service.MybatisMapper;
import org.springframework.beans.factory.config.BeanDefinitionHolder;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.context.annotation.ClassPathBeanDefinitionScanner;
import org.springframework.core.type.filter.AnnotationTypeFilter;
import org.springframework.stereotype.Component;
import java.util.Set;
public class MyClasspathBeanDefinitionScanner extends ClassPathBeanDefinitionScanner {
public MyClasspathBeanDefinitionScanner(BeanDefinitionRegistry registry, boolean useDefaultFilters) {
super(registry, useDefaultFilters);
}
protected void registerFilters() {
addIncludeFilter(new AnnotationTypeFilter(MyClassMapper.class));
}
@Override
protected Set<BeanDefinitionHolder> doScan(String... basePackages) {
return super.doScan(basePackages);
}
}
四、自定义ImportBeanDefinitionRegistrar
package com.example.demo.component;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.context.annotation.ImportBeanDefinitionRegistrar;
import org.springframework.core.type.AnnotationMetadata;
import org.springframework.stereotype.Component;
@Component
public class MyImportBeanDefinitionRegistrar implements ImportBeanDefinitionRegistrar {
public static String BASE_PACKAGE = "com.example.demo.service";
@Override
public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
MyClasspathBeanDefinitionScanner scanner = new MyClasspathBeanDefinitionScanner(registry, false);
scanner.registerFilters();
scanner.doScan(BASE_PACKAGE);
}
}
其中调用MyClasspathBeanDefinitionScanner进行组件扫描。
五、将自定义ImportBeanDefinitionRegistrar配置到容器
package com.example.demo.config;
import com.example.demo.component.MyClasspathBeanDefinitionScanner;
import com.example.demo.component.MyImportBeanDefinitionRegistrar;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;
@Configuration
@Import(MyImportBeanDefinitionRegistrar.class)
public class MyConfig {
}
六、测试代码
package com.example.demo;
import com.example.demo.service.HelloService;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.annotation.PropertySource;
@SpringBootApplication
@PropertySource("classpath:my.properties")
public class DemoApplication {
public static void main(String[] args) {
ConfigurableApplicationContext context = SpringApplication.run(DemoApplication.class, args);
System.out.println("abc");
HelloService helloService = (HelloService) context.getBean("helloService");
System.out.println(helloService);
}
}