PostConstruct方法中的java.lang.reflect.InvocationTargetException

Question

我正在尝试使用java反射和@PostConstruct spring注释验证方法列表返回的值，如下面的代码片段所示：

@Service("appConfigService")
public class AppConfigServiceImpl implements AppConfigService{       

    //rest of source code including constructor and other methods is omitted 

    @Override
    public String getServerURL(){//example of a method I am invoking in the postConstruct phase
       //method body omitted
    }

    @PostConstruct
    public void postConstruct() {
        try {
            Class<AppConfigServiceImpl> classObject = AppConfigServiceImpl.class;
            AppConfigServiceImpl appConfigServiceImpl = classObject.newInstance();
            Method[] methods = classObject.getMethods();
            for(Method method: methods)     
                method.invoke(appConfigServiceImpl);            
        } catch (IllegalAccessException | IllegalArgumentException | InvocationTargetException | InstantiationException e) {
            e.printStackTrace();
        }
    }
}

但是当spring执行postConstruct()方法时，会抛出java.lang.reflect.InvocationTargetException。我无法弄清楚异常的来源。任何帮助都将受到欢迎。