2019.6.28 Spring注解

6.28

• Spring提供了获取操作系统的信息：

  ApplicationContext applicationContext = new AnnotationConfigApplicationContext(Myconfig.class);
          ConfigurableEnvironment contextEnvironment = (ConfigurableEnvironment) applicationContext.getEnvironment();
  /*对应jvm参数中的os.name*/
          String ospropertyname = contextEnvironment.getProperty("os.name");
          System.out.println(ospropertyname);
  

• Conditional根据条件判断是否将bean注册到容器中

  1. 需要将注解bean的方法加上@Conditional

  2. @Conditiona接受一个Condition类型的CLass数组，

  3. 需要写一个条件类来实现Conditional接口里面的matches

  4. matches的方法形参是ConditionContext conditionContext, AnnotatedTypeMetadata annotatedTypeMetadata

     public class Os implements Condition {
         @Override
         public boolean matches(ConditionContext conditionContext, AnnotatedTypeMetadata annotatedTypeMetadata) {
             /*获取ioc使用的beanfactory*/
             ConfigurableListableBeanFactory beanFactory = conditionContext.getBeanFactory();
             /*获取bean定义的注册类*/
             BeanDefinitionRegistry registry = conditionContext.getRegistry();
             Environment environment = conditionContext.getEnvironment();
             String ospropertyname = environment.getProperty("os.name");
     
             /*判断容器中是否含有bean*/
             //boolean person = registry.containsBeanDefinition("person");
             if(ospropertyname.contains("window")){
                 return true;
             }
             return false;
         }
     }