在spring 中使用自定义注解

spring加载自定义注解的条件

只要注解实现@Component
spring 中的源码如下：

protected void registerDefaultFilters() {   
   //只扫描含有Component注解的类
   this.includeFilters.add(new AnnotationTypeFilter(Component.class));
   ClassLoader cl = ClassPathScanningCandidateComponentProvider.class.getClassLoader();
   try {    
      this.includeFilters.add(new AnnotationTypeFilter(((Class) ClassUtils.forName("javax.annotation.ManagedBean", cl)), false));   
   }catch (ClassNotFoundException ex) {     
   }   
   try {      
      this.includeFilters.add(new AnnotationTypeFilter(((Class) ClassUtils.forName("javax.inject.Named", cl)), false));      
      logger.debug("JSR-330 'javax.inject.Named' annotation found and supported for component scanning");   
   }  
   catch (ClassNotFoundException ex) {     
   // JSR-330 API not available - simply skip.  
   }
}

从上面的源码中可以看到，只要一个注解类实现@Componet，Spring就可以扫描到容器中。

spring ApplicationContextAware接口

当一个类实现了这个接口（ApplicationContextAware）之后，这个类就可以方便获得ApplicationContext中的所有bean。

@Component
public class SpringContextHelper implements ApplicationContextAware {  
    private static ApplicationContext context = null;  
    @Override  
    public void setApplicationContext(ApplicationContext applicationContext)  
            throws BeansException {  
        context = applicationContext;  
    }  
    public static Object getBean(String name){  
        return context.getBean(name);  
    }  
}