SpringBoot复习：（21）自定义ImportBeanDefinitionRegistrar

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));}@Overrideprotected 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";@Overridepublic 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);}}