package com.atlassian.activeobjects.spring;
   
   import org.springframework.beans.factory.FactoryBean;
   
   import static com.google.common.base.Preconditions.checkNotNull;
   
   public final class OptionalServiceFactoryBean<T> implements FactoryBean {
       private final T service;
       private final T defaultValue;
      private final Class<T> type;
  
      public OptionalServiceFactoryBean(Class<T> type, T service, T defaultValue) {
          this.type = checkNotNull(type);
          this.service = checkNotNull(service);
          this.defaultValue = checkNotNull(defaultValue);
      }
  
      @Override
      public Object getObject() throws Exception {
          try {
              service.toString();
              return service;
          } catch (RuntimeException e) {
              if (e.getClass().getSimpleName().equals("ServiceUnavailableException")) {
                  return defaultValue;
              }
              throw e;
          }
      }
  
      @Override
      public Class getObjectType() {
          return type;
      }
  
      @Override
      public boolean isSingleton() {
          return true;
      }
  }