Spring注解@ComponentScan

Spring注解@ComponentScan 一、@ComponentScan注解 1、@ComponentScan注解作用

@ComponentScan用于扫描指定包下的类，将标注有@Controller、@Service、@Repository、@Component4个注解其中一个的类扫描到Spring容器，作为Spring
Bean

2、@ComponentScan使用实例 （1）项目结构

（2）标注有标注有@Controller、@Service、@Repository、@Component4个注解其中一个的类

@Controller
public class Book {
}

@Service
public class Persion {
}

@Repository
public class Student {
}

@Component
public class User {
}

（3）标注有@ComponentScan注解的配置类

@Configuration

@ComponentScan(value = "com.dashu")
public class BeanConfig {

}

（4）测试类

import com.dashu.config.BeanConfig;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;


public class Main {

    public static void main(String[] args) {
        
        AnnotationConfigApplicationContext annotationConfigApplicationContext = new AnnotationConfigApplicationContext(BeanConfig.class);
        String[] beanDefinitionNames2 = annotationConfigApplicationContext.getBeanDefinitionNames();
        for (String name : beanDefinitionNames2) {
            System.out.println(name);
        }
    }

}

（5）测试结果

二、@ComponentScan注解扫描规则

根据参数includeFilters指定包含扫描哪些组件

根据参数excludeFilters指定排除扫描哪些组件

三、排除excludeFilters 1、常用排除规则

//按照注解来指定规则
FilterType.ANNOTATION
//按照给定的类型来指定规则
FilterType.ASSIGNABLE_TYPE

2、排除案例 （1）标注有@ComponentScan注解的配置类，并指定两个常用的排除规则

@Configuration

@ComponentScan(value = "com.dashu",excludeFilters = {
        //按照注解的方式，排除标有注解@Controller的类
        @ComponentScan.Filter(type = FilterType.ANNOTATION,classes = {Controller.class}),
        //按照指定类型，排除Persion类
        @ComponentScan.Filter(type = FilterType.ASSIGNABLE_TYPE,classes = {Persion.class})
})
public class BeanConfig {

}

(2) 测试结果

四、指定包含includeFilters 1、常用包含规则

//按照注解来指定规则
FilterType.ANNOTATION
//按照给定的类型来指定规则
FilterType.ASSIGNABLE_TYPE
    
//使用指定包含规则，需要禁用掉默认的扫描规则
useDefaultFilters = false

2、指定包含案例 （1）标注有@ComponentScan注解的配置类，并指定两个常用的指定包含规则

@Configuration

@ComponentScan(value = "com.dashu",

        includeFilters = {
        //按照注解的方式，排除标有注解@Controller的类
        @ComponentScan.Filter(type = FilterType.ANNOTATION,classes = {Controller.class}),
        //按照指定类型，排除Persion类
        @ComponentScan.Filter(type = FilterType.ASSIGNABLE_TYPE,classes = {Persion.class})},

        //禁用掉默认的扫描规则
        useDefaultFilters = false)
public class BeanConfig {

}

(2) 测试结果

五、FilterType规则

public enum FilterType {

	
	ANNOTATION,

	
	ASSIGNABLE_TYPE,

	
	ASPECTJ,

	
	REGEX,

	
	CUSTOM

}

六、自定义规则

CUSTOM

自定义规则必须是TypeFilter的实现类

1、项目结构

2、创建自定义规则类 MyTypeFilter

import org.springframework.core.io.Resource;
import org.springframework.core.type.Annotationmetadata;
import org.springframework.core.type.Classmetadata;
import org.springframework.core.type.classreading.metadataReader;
import org.springframework.core.type.classreading.metadataReaderFactory;
import org.springframework.core.type.filter.TypeFilter;
import java.io.IOException;

public class MyTypeFilter implements TypeFilter {

    
    @Override
    public boolean match(metadataReader metadataReader, metadataReaderFactory metadataReaderFactory) throws IOException {

        //获取当前正在扫描的类的注解信息
        Annotationmetadata annotationmetadata = metadataReader.getAnnotationmetadata();

        //获取当前正在扫描的类的类信息
        Classmetadata classmetadata = metadataReader.getClassmetadata();

        //获取当前正在扫描的类的资源信息
        Resource resource = metadataReader.getResource();

        //获取当前类名
        String className = classmetadata.getClassName();

        //判断当前类名是否包含Persion，包含Persion则返回true，将该类扫描到容器，否则返回false过滤
        if (className.indexOf("Persion") != -1){

            return true;
        }

        return false;
    }
}

3、标注有@ComponentScan注解的配置类，并指定自定义规则

org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.FilterType;


@Configuration

@ComponentScan(value = "com.dashu",

        includeFilters = {
        //自定义规则
        @ComponentScan.Filter(type = FilterType.CUSTOM,classes = {MyTypeFilter.class})},

        //禁用掉默认的扫描规则
        useDefaultFilters = false)
public class BeanConfig {

}

4、测试结果