canna-cloud【五】spring boot延迟自定义枚举的static值初始化

1、自定义注解：InitEnum

 @Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface InitEnum {
    public static final Object[] NULL_ITEM = { "" };
    public static final Class[] parameterTypes = { String.class };
}

2、反射创建实例

     public static <T> T getInstance(Class<T> clazz) throws Exception {
        try {
            return clazz.newInstance();
        } catch (InstantiationException | IllegalAccessException e) {
            log.info("", e);
            throw new Exception("实例化失败");
        }
    }

3、在需要的初始化对象中添加注解

 @InitEnum
public class FileModuleEnum {

    private static final Map<String, FileModuleEnum> nameEnumMap = new ConcurrentHashMap<>();

    protected FileModuleEnum(String name) {
        if (!nameEnumMap.containsKey(name)) {
            nameEnumMap.put(name, this);
        }
    }

    public static FileModuleEnum valueOf(String name) {
        if (name == null)
            throw new NullPointerException("Name is null");

        FileModuleEnum result = nameEnumMap.get(name);
        if (result != null) {
            return result;
        }

        throw new IllegalArgumentException("No enum constant exists, name is." + name);
    }

}

4、监听启动后进行初始化

 @Log4j2
@Component
@Order(value = 0)
public class EndStartedListener implements ApplicationListener<ContextRefreshedEvent> {

    @Resource
    private SpringClassService springClassService;

    @Override
    public void onApplicationEvent(ContextRefreshedEvent event) {

        try {
            this.initEnum();
        } catch (Exception e) {
            log.error("", e);
        }

    }

    private void initEnum() throws Exception {
        List<Class> classList = springClassService.listAllClass();
        for (Class clazz: classList) {
            if (clazz.isAnnotationPresent(InitEnum.class)) {
                Object temp = BeanTransferUtils.getInstance(clazz, InitEnum.parameterTypes, InitEnum.NULL_ITEM);
                temp = null;
            }
        }
    }

}