目录

• @ComponentScan注解的使用
  • 1、注解定义
  • 2、使用
    • 1.环境准备
    • 2.excludeFilters的使用
    • 3.includeFilters的使用
    • 4.自定义过滤规则
• 关于@ComponentScan注解的一些细节

@Retention(RetentionPolicy.RUNTIME)@Target(ElementType.TYPE)@Documented@Repeatable(ComponentScans.class)public @interface ComponentScan {   /**    * 扫描路径    * @ComponentScan(value = "spring.annotation.componentscan")    */   @AliasFor("basePackages")   String[] value() default {};   /**    * 扫描路径    */   @AliasFor("value")   String[] basePackages() default {};   /**    * 指定扫描类    * @ComponentScan(basePackageClasses = {BookDao.class, BookService.class})    */   Class<?>[] basePackageClasses() default {};   /**    * 命名注册的Bean，可以自定义实现命名Bean，    * 1、@ComponentScan(value = "spring.annotation.componentscan",nameGenerator = MyBeanNameGenerator.class)    * MyBeanNameGenerator.class 需要实现 BeanNameGenerator 接口，所有实现BeanNameGenerator 接口的实现类都会被调用    * 2、使用 AnnotationConfigApplicationContext 的 setBeanNameGenerator方法注入一个BeanNameGenerator    * BeanNameGenerator beanNameGenerator = (definition,registry)-> String.valueOf(new Random().nextInt(1000));    * AnnotationConfigApplicationContext annotationConfigApplicationContext = new AnnotationConfigApplicationContext();    * annotationConfigApplicationContext.setBeanNameGenerator(beanNameGenerator);    * annotationConfigApplicationContext.register(MainConfig2.class);    * annotationConfigApplicationContext.refresh();    * 第一种方式只会重命名@ComponentScan扫描到的注解类    * 第二种只有是初始化的注解类就会被重命名    * 列如第一种方式不会重命名 @Configuration 注解的bean名称，而第二种就会重命名 @Configuration 注解的Bean名称    */   Class<? extends BeanNameGenerator> nameGenerator() default BeanNameGenerator.class;   /**    * 用于解析@Scope注解，可通过 AnnotationConfigApplicationContext 的 setScopeMetadataResolver 方法重新设定处理类    * ScopeMetadataResolver scopeMetadataResolver = definition -> new ScopeMetadata();  这里只是new了一个对象作为演示，没有做实际的逻辑操作    * AnnotationConfigApplicationContext annotationConfigApplicationContext = new AnnotationConfigApplicationContext();    * annotationConfigApplicationContext.setScopeMetadataResolver(scopeMetadataResolver);    * annotationConfigApplicationContext.register(MainConfig2.class);    * annotationConfigApplicationContext.refresh();    * 也可以通过@ComponentScan 的 scopeResolver 属性设置    *@ComponentScan(value = "spring.annotation.componentscan",scopeResolver = MyAnnotationScopeMetadataResolver.class)    */   Class<? extends ScopeMetadataResolver> scopeResolver() default AnnotationScopeMetadataResolver.class;   /**    * 用来设置类的代理模式    */   ScopedProxyMode scopedProxy() default ScopedProxyMode.DEFAULT;   /**    * 扫描路径 如 resourcePattern = "**/*.class"    * 使用  includeFilters 和 excludeFilters 会更灵活    */   String resourcePattern() default ClassPathScanningCandidateComponentProvider.DEFAULT_RESOURCE_PATTERN;   /**    * 指示是否应启用对带有{@code @Component}，{@ code @Repository}，    * {@ code @Service}或{@code @Controller}注释的类的自动检测。    */   boolean useDefaultFilters() default true;   /**    * 对被扫描的包或类进行过滤，若符合条件，不论组件上是否有注解，Bean对象都将被创建    * @ComponentScan(value = "spring.annotation.componentscan",includeFilters = {    *     @ComponentScan.Filter(type = FilterType.ANNOTATION, classes = {Controller.class, Service.class}),    *     @ComponentScan.Filter(type = FilterType.ASSIGNABLE_TYPE, classes = {SchoolDao.class}),    *     @ComponentScan.Filter(type = FilterType.CUSTOM, classes = {MyTypeFilter.class}),    *     @ComponentScan.Filter(type = FilterType.ASPECTJ, pattern = "spring.annotation..*"),    *     @ComponentScan.Filter(type = FilterType.REGEX, pattern = "^[A-Za-z.]+Dao$")    * },useDefaultFilters = false)    * useDefaultFilters 必须设为 false    */   Filter[] includeFilters() default {};   /**    * 指定哪些类型不适合进行组件扫描。    * 用法同 includeFilters 一样    */   Filter[] excludeFilters() default {};   /**    * 指定是否应注册扫描的Bean以进行延迟初始化。    * @ComponentScan(value = "spring.annotation.componentscan",lazyInit = true)    */   boolean lazyInit() default false;   /**    * 用于 includeFilters 或 excludeFilters 的类型筛选器    */   @Retention(RetentionPolicy.RUNTIME)   @Target({})   @interface Filter {      /**       * 要使用的过滤器类型，默认为 ANNOTATION 注解类型       * @ComponentScan.Filter(type = FilterType.ANNOTATION, classes = {Controller.class, Service.class})       */      FilterType type() default FilterType.ANNOTATION;      /**       * 过滤器的参数，参数必须为class数组，单个参数可以不加大括号       * 只能用于 ANNOTATION 、ASSIGNABLE_TYPE 、CUSTOM 这三个类型       * @ComponentScan.Filter(type = FilterType.ANNOTATION, value = {Controller.class, Service.class})       * @ComponentScan.Filter(type = FilterType.ASSIGNABLE_TYPE, classes = {SchoolDao.class})       * @ComponentScan.Filter(type = FilterType.CUSTOM, classes = {MyTypeFilter.class})       */      @AliasFor("classes")      Class<?>[] value() default {};      /**       * 作用同上面的 value 相同       * ANNOTATION 参数为注解类，如  Controller.class, Service.class, Repository.class       * ASSIGNABLE_TYPE 参数为类，如 SchoolDao.class       * CUSTOM  参数为实现 TypeFilter 接口的类 ，如 MyTypeFilter.class       * MyTypeFilter 同时还能实现 EnvironmentAware，BeanFactoryAware，BeanClassLoaderAware，ResourceLoaderAware        * 这四个接口       * EnvironmentAware       * 此方法用来接收 Environment 数据 ，主要为程序的运行环境，Environment 接口继承自 PropertyResolver 接口，       * 详细内容在下方       * @Override       * public void setEnvironment(Environment environment) {       *    String property = environment.getProperty("os.name");       * }       *        * BeanFactoryAware       * BeanFactory Bean容器的根接口，用于操作容器，如获取bean的别名、类型、实例、是否单例的数据       * @Override       * public void setBeanFactory(BeanFactory beanFactory) throws BeansException {       *     Object bean = beanFactory.getBean("BeanName")       * }       *        * BeanClassLoaderAware       * ClassLoader 是类加载器，在此方法里只能获取资源和设置加载器状态       * @Override       * public void setBeanClassLoader(ClassLoader classLoader) {       *     ClassLoader parent = classLoader.getParent();       * }       *        * ResourceLoaderAware       * ResourceLoader 用于获取类加载器和根据路径获取资源       * public void setResourceLoader(ResourceLoader resourceLoader) {       *     ClassLoader classLoader = resourceLoader.getClassLoader();       * }       */      @AliasFor("value")      Class<?>[] classes() default {};      /**       * 这个参数是 classes 或 value 的替代参数，主要用于 ASPECTJ 类型和  REGEX 类型       * ASPECTJ  为 ASPECTJ 表达式       * @ComponentScan.Filter(type = FilterType.ASPECTJ, pattern = "spring.annotation..*")       * REGEX  参数为 正则表达式       * @ComponentScan.Filter(type = FilterType.REGEX, pattern = "^[A-Za-z.]+Dao$")       */      String[] pattern() default {};   }}

  <dependencies>    <!-- https://mvnrepository.com/artifact/org.springframework/spring-context -->		<dependency>		    <groupId>org.springframework</groupId>		    <artifactId>spring-context</artifactId>		    <version>4.3.26.RELEASE</version>		</dependency>		<!-- https://mvnrepository.com/artifact/junit/junit -->		<dependency>		  <groupId>junit</groupId>			<artifactId>junit</artifactId>			<version>4.12</version>			<scope>test</scope>		</dependency>	  </dependencies>

public class IoCTest {	@Test	public void test01() {		//获取Spring的IOC容器		ApplicationContext applicationContext=new AnnotationConfigApplicationContext(SpringConfig.class);		//从容器中获取bean	    String[] names= applicationContext.getBeanDefinitionNames();		       for(String i:names) {	    	   System.out.println(i);	       }	}}

@Configuration@ComponentScan(basePackages = "com.learn",excludeFilters = {  @Filter(type = FilterType.ANNOTATION,classes = {Controller.class,Service.class})})public class SpringConfig {}

@Configuration@ComponentScan(basePackages = "com.learn",includeFilters = {  @Filter(type = FilterType.ANNOTATION,classes = {Controller.class,Service.class})},useDefaultFilters = false)public class SpringConfig {}

public class MyTypeFilter implements TypeFilter {    /**     * 两个参数的含义：     * metadataReader：包含读取到的当前正在扫描的类的信息     * metadataReaderFactory:可以获取到当前正在扫描的类的其他类信息(如父类和接口)     * match方法返回false即不通过过滤规则，true通过过滤规则     */	@Override	public boolean match(MetadataReader metadataReader, MetadataReaderFactory metadataReaderFactory)			throws IOException {		// TODO Auto-generated method stub	     //获取当前类注解的信息        AnnotationMetadata annotationMetadata = metadataReader.getAnnotationMetadata();        //获取当前正在扫描的类的类信息        ClassMetadata classMetadata = metadataReader.getClassMetadata();        //获取当前类资源（类的路径）        Resource resource = metadataReader.getResource();        String className = classMetadata.getClassName();        if(className.contains("controller")){            return true;        }        return false;	}}

@Configuration@ComponentScan(basePackages = "com.learn",includeFilters = {		@Filter(type = FilterType.ASSIGNABLE_TYPE,classes = {Person.class}),		@Filter(type = FilterType.CUSTOM,classes = {MyTypeFilter.class}),},useDefaultFilters = false)public class SpringConfig {}

//@Configurationpublic class ProfileConfig {    @Component("class1")    private static class Class1 {        @Bean        public Class3 class3() {            return new Class3();        }    }    @Component("class2")    static class Class2 {    }    //@Component("class3")    protected static class Class3 {    }//    @Component("class4") //出错//    protected class Class4 {////    }}--------------------------------------------------------@Retention(RetentionPolicy.RUNTIME)@Target(ElementType.METHOD)//@Beanpublic @interface MyBean {    public static final int age1=3; //常量可以    int age=2;    public abstract String value() default "qwer"; //属性可以    //内部类可以    @Component    @DependsOn("myBean.EventZ") //依赖事件bean的创建，保证该bean在事件bean之后创建        //细节：因为是内部类，所以默认bean的id是类名首字母小写，不是eventZ而是myBean.EventZ    class EventSource {        public EventSource(){            System.out.println("事件源创建了...");        }    }    @Component//("eventZ")    public static class EventZ {        public EventZ(){            System.out.println("事件创建了...");        }    }}