Spring注解[email protected]、@Bean、@ComponentScan的过滤规则FilterType详解

@Configuration和@Bean

从Spring3.0，@Configuration用于定义配置类，可替换xml配置文件，被注解的类内部包含有一个或多个被@Bean注解的方法，这些方法将会被AnnotationConfigApplicationContext或AnnotationConfigWebApplicationContext类进行扫描，并用于构建bean定义，初始化Spring容器。

注意：@Configuration注解的配置类有如下要求：

• @Configuration不可以是final类型；
• @Configuration不可以是匿名类；
• 嵌套的configuration必须是静态类。

//@Configuration告诉Spring这是一个配置类
@Configuration
public class MainConfig {

    //给容器中注册一个Bean，类型为返回值的类型，方法名作为id；也可以指定id：@Bean("id")
    @Bean
    public Person person(){
        return new Person("zhangsan", 18);
    }
}

public class MainTest {
    public static void main(String[] args) {
        AnnotationConfigApplicationContext ac = new AnnotationConfigApplicationContext(MainConfig.class);
        Person person = (Person) ac.getBean("person");
        System.out.println(person);
        //获取person的类型
        String[] beanNamesForType = ac.getBeanNamesForType(Person.class);
        for(String name: beanNamesForType){
            System.out.println(name);
        }
    }
}

Person{name='zhangsan', age=18}
person

@ComponentScan

• basePackages与value: 用于指定包的路径，进行扫描

• basePackageClasses: 用于指定某个类的包的路径进行扫描

• nameGenerator: bean的名称的生成器

• useDefaultFilters: 是否开启对@Component，@Repository，@Service，@Controller的类进行检测

• includeFilters: 包含的过滤条件

  • FilterType.ANNOTATION：按照注解过滤
  • FilterType.ASSIGNABLE_TYPE：按照给定的类型
  • FilterType.ASPECTJ：使用ASPECTJ表达式
  • FilterType.REGEX：正则
  • FilterType.CUSTOM：自定义规则

• excludeFilters: 排除的过滤条件，用法和includeFilters一样

示例：
在容器中注册Controller、service和dao

package pers.zhang.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.FilterType;
import org.springframework.stereotype.Controller;
import org.springframework.stereotype.Service;
import pers.zhang.bean.Person;

//@Configuration告诉Spring这是一个配置类
@Configuration
@ComponentScan(value = "pers.zhang")//开启扫描
public class MainConfig {

    //给容器中注册一个Bean，类型为返回值的类型，方法名作为id；也可以指定id：@Bean("id")
    @Bean
    public Person person(){
        return new Person("zhangsan", 18);
    }
}

测试：

@Test
    public void test01(){
        AnnotationConfigApplicationContext ac = new AnnotationConfigApplicationContext(MainConfig.class);
        String[] definitionNames = ac.getBeanDefinitionNames();
        for(String name : definitionNames){
            System.out.println(name);
        }
    }

输出：

org.springframework.context.annotation.internalConfigurationAnnotationProcessor
org.springframework.context.annotation.internalAutowiredAnnotationProcessor
org.springframework.context.annotation.internalRequiredAnnotationProcessor
org.springframework.context.annotation.internalCommonAnnotationProcessor
org.springframework.context.event.internalEventListenerProcessor
org.springframework.context.event.internalEventListenerFactory
mainConfig
bookController
bookDao
bookService
person

使用excludeFilters和includeFilters过滤扫描

Filter中type的类型

• ANNOTATION：注解类型
• ASSIGNABLE_TYPE：指定的类型
• ASPECTJ：按照Aspectj的表达式，基本上不会用到
• REGEX：按照正则表达式
• CUSTOM：自定义规则

@ComponentScan(value = "pers.zhang", excludeFilters = {
        @ComponentScan.Filter(type = FilterType.ANNOTATION, classes = {Controller.class, Service.class})
})//开启扫描

//过滤掉Controller和Service注解的Bean
//excludeFilters参数为Filter数组，type为过滤规则

输出：

org.springframework.context.annotation.internalConfigurationAnnotationProcessor
org.springframework.context.annotation.internalAutowiredAnnotationProcessor
org.springframework.context.annotation.internalRequiredAnnotationProcessor
org.springframework.context.annotation.internalCommonAnnotationProcessor
org.springframework.context.event.internalEventListenerProcessor
org.springframework.context.event.internalEventListenerFactory
mainConfig
bookDao
person

---

@ComponentScan(value = "pers.zhang", includeFilters = {
        @ComponentScan.Filter(type = FilterType.ANNOTATION, classes = {Controller.class})
}, useDefaultFilters = false)//开启扫描

//过滤：只包含Controller
//useDefaultFilters默认为true，改为false

输出：

org.springframework.context.annotation.internalConfigurationAnnotationProcessor
org.springframework.context.annotation.internalAutowiredAnnotationProcessor
org.springframework.context.annotation.internalRequiredAnnotationProcessor
org.springframework.context.annotation.internalCommonAnnotationProcessor
org.springframework.context.event.internalEventListenerProcessor
org.springframework.context.event.internalEventListenerFactory
mainConfig
bookController
person

---

通过类型指定过滤规则：

@ComponentScan(value = "pers.zhang", includeFilters = {
        @ComponentScan.Filter(type = FilterType.ANNOTATION, classes = {Controller.class}),
        @ComponentScan.Filter(type = FilterType.ASSIGNABLE_TYPE, classes = {BookService.class})
}, useDefaultFilters = false)//开启扫描
//所有BookService类型（包括子类）都在扫描的时候添加为Bean

输出：

org.springframework.context.annotation.internalConfigurationAnnotationProcessor
org.springframework.context.annotation.internalAutowiredAnnotationProcessor
org.springframework.context.annotation.internalRequiredAnnotationProcessor
org.springframework.context.annotation.internalCommonAnnotationProcessor
org.springframework.context.event.internalEventListenerProcessor
org.springframework.context.event.internalEventListenerFactory
mainConfig
bookController
bookService			//被扫描进来
person

---

自定义过滤规则
写一个TypeFilter的实现类：

package pers.zhang.config;

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   //MetadataReader：当前正在扫描的类的信息；    MetadataReaderFactory：可以获取到其它任何类信息
    public boolean match(MetadataReader metadataReader, MetadataReaderFactory metadataReaderFactory) throws IOException {
        //获取当前类注解
        AnnotationMetadata annotationMetadata = metadataReader.getAnnotationMetadata();
        //获取当前类的类信息
        ClassMetadata classMetadata = metadataReader.getClassMetadata();
        //获取当前类资源信息（路径）
        Resource resource = metadataReader.getResource();

        String className = classMetadata.getClassName();
        System.out.println("--->" + className);
        //类名不包含er，则注册为Bean
        if(!className.contains("er")){
            return true;
        }
        return false;
    }
}

@ComponentScan(value = "pers.zhang", includeFilters = {
//        @ComponentScan.Filter(type = FilterType.ANNOTATION, classes = {Controller.class}),
//        @ComponentScan.Filter(type = FilterType.ASSIGNABLE_TYPE, classes = {BookService.class}),
        @ComponentScan.Filter(type = FilterType.CUSTOM, classes = {MyTypeFilter.class})
}, useDefaultFilters = false)//开启扫描