SpringBoot -- 获取SpringContext上下文

在开发过程中，我们可能会遇到需要动态加载某个bean的实例，或者动态获取再配置文件中配置的某个属性。此时我们就会用到SpringContext上下文。网上有许多获取SpringContext上下文的工具类，这里主要记录一下是如何获取到上下文的。

• • Spring Bean 的生命周期
  • SpringContextUtils 工具类

从bean的生命周期可以看出，如果Bean实现了ApplicationContextAware接口，那么在bean准备阶段就会调用setApplicationContext()方法，并注入Spring上下文。因此，我们只需要创建一个组件，并继承ApplicationContextAware接口，此时我们在setApplicationContext()方法中就可以获取到上下文信息。

@Component
public class SpringContextUtils implements ApplicationContextAware {
    private static ApplicationContext applicationContext;

    
    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        this.applicationContext = applicationContext;
    }

    
    public static ApplicationContext getApplicationContext(){
        return applicationContext;
    }

    
    public static String[] getBeanDefinitionNames(){
        return applicationContext.getBeanDefinitionNames();
    }

    
    public static Object getBean(String name){
        return applicationContext.getBean(name);
    }

    
    public static  T getBean(Class clazz){
        return applicationContext.getBean(clazz);
    }

    
    public static Class getType(String name){
        return applicationContext.getType(name);
    }

    
    public static Object getProperty(String propertyName){
        ConfigurableEnvironment env = (ConfigurableEnvironment) applicationContext.getEnvironment();
        return env.getProperty(propertyName);
    }

    
    public static List getPropertyList(String propertyPrefix){

        AtomicReference> result = new AtomicReference<>();

        ConfigurableEnvironment env = (ConfigurableEnvironment) applicationContext.getEnvironment();

        env.getPropertySources().stream().forEach(propertySource->{
            if (propertySource instanceof OriginTrackedMapPropertySource) {
                List props = Arrays.asList(((OriginTrackedMapPropertySource) propertySource).getPropertyNames());
                result.set(props.stream().filter(e -> e.startsWith(propertyPrefix)).collect(Collectors.toList()));
            }
        });

        return result.get();
    }

    
    public static boolean containProperty(String propertyName,boolean notBlank){

        Object prop =  applicationContext.getEnvironment().getProperty(propertyName);
        if(null==prop){
            return false;
        }else if(notBlank && Strings.isBlank(prop.toString())){
            return false;
        }
        return true;
    }
}