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1.@CompentScan与@CompentScans
@CompentScan
为扫描包注解,只能作用于类上,一个类上可以有多个@CompentScan注解。
等价于 <context:component-scan base-package="com.java" ></context:component-scan>
使用了@ComponentScan注解后,指定包下的@Controller,@Service,@Repository,@Compent才会生效。
@component注解属性说明:
//excludeFilters = Filter[] :指定扫描的时候按照什么规则排除那些组件
//includeFilters = Filter[] :指定扫描的时候只需要包含哪些组件
//FilterType.ANNOTATION:按照注解
//FilterType.ASSIGNABLE_TYPE:按照给定的类型;
//FilterType.ASPECTJ:使用ASPECTJ表达式
//FilterType.REGEX:使用正则指定
//FilterType.CUSTOM:使用自定义规则
特别注意:过滤器必须实现TypeFilter接口,同时要使过滤器生效,必须将useDefaultFilters设置为false,该属性默认为true。
<context:component-scan base-package="com.java" use-default-filters="false"></context:component-scan>
@ComponentScan(basePackages = {"com.java"},useDefaultFilters = false,
includeFilters = { @ComponentScan.Filter(type = FilterType.ANNOTATION,classes ={Controller.class}) })
@CompentScans
存在多个@ComponentScan时,可以使用@ComponentScans将这些@ComponentScan放在里面统一管理,@ComponentScans是一个数组。
@Configuration
@ComponentScan(basePackages = {"com.java.dao"})
@ComponentScan(basePackages = {"com.java.service"})
public class BeanConfig {
@Bean("personAlias")
public Person person2(){
return new Person("2222","lisi");
}
}
//等价
@Configuration
@ComponentScans({
@ComponentScan(basePackages = {"com.java.dao"}),
@ComponentScan(basePackages = {"com.java.service"})
})
public class BeanConfig {
@Bean("personAlias")
public Person person2(){
return new Person("2222","lisi");
}
}
2.实例
条件:在包中已经建立有controller/service/dao的各层类,并且标有对应注解。
@Configuration
@ComponentScans({
@ComponentScan(basePackages = {"com.java"},useDefaultFilters = false,
includeFilters = {
//只有Controller注解才能注进来
@ComponentScan.Filter(type = FilterType.ANNOTATION,classes ={Controller.class}),
//只有符合自定义规则的类才能注进来
@ComponentScan.Filter(type = FilterType.CUSTOM,classes ={MyTypeFilter.class})
}
)
})
public class BeanConfig {
@Bean("personAlias")
public Person person2(){
return new Person("2222","lisi");
}
}
过滤器:过滤器必须实现TypeFilter接口
public class MyTypeFilter implements TypeFilter {
/**
* metadataReader:读取到的当前正在扫描的类的信息
* metadataReaderFactory:可以获取到其他任何类信息的
*/
@Override
public boolean match(MetadataReader metadataReader, MetadataReaderFactory metadataReaderFactory) throws IOException {
//获取当前类注解的信息
AnnotationMetadata annotationMetadata = metadataReader.getAnnotationMetadata();
System.out.println(annotationMetadata);
if(annotationMetadata.getClassName().contains("vice")){
return true;
}
//获取当前正在扫描的类的类信息
ClassMetadata classMetadata = metadataReader.getClassMetadata();
//获取当前类资源(类的路径)
Resource resource = metadataReader.getResource();
//获取任何类,可以是接口,可以是子类
MetadataReader service = metadataReaderFactory.getMetadataReader("com.java.dao.PersonDao");
return false;
}
}
测试类
public class BeanDependencyInjectionTest {
public static void main(String[] args) {
System.out.println("-----------------------------annotation 注解方式注入-----------------------------------");
//annotation 注解方式注入
ApplicationContext applicationContext1 = new AnnotationConfigApplicationContext(BeanConfig.class);
Person person1 = applicationContext1.getBean(Person.class);
System.out.println("person1---->"+person1);
//获取所有注入Bean的名称
String[] beanDefinitionNames1 = applicationContext1.getBeanDefinitionNames();
for (String name : beanDefinitionNames1) {
System.out.println(name);
}
}
}
测试结果:我们可以看到只有controller和Service才能注入,dao是注入不进来的。
-----------------------------annotation 注解方式注入-----------------------------------
org.springframework.core.type.classreading.AnnotationMetadataReadingVisitor@382db087
org.springframework.core.type.classreading.AnnotationMetadataReadingVisitor@15bfd87
org.springframework.core.type.classreading.AnnotationMetadataReadingVisitor@543e710e
org.springframework.core.type.classreading.AnnotationMetadataReadingVisitor@57f23557
org.springframework.core.type.classreading.AnnotationMetadataReadingVisitor@3d0f8e03
org.springframework.core.type.classreading.AnnotationMetadataReadingVisitor@6366ebe0
person1---->Person{id='2222', name='lisi'}
org.springframework.context.annotation.internalConfigurationAnnotationProcessor
org.springframework.context.annotation.internalAutowiredAnnotationProcessor
org.springframework.context.annotation.internalCommonAnnotationProcessor
org.springframework.context.event.internalEventListenerProcessor
org.springframework.context.event.internalEventListenerFactory
beanConfig
personController
personService
personAlias