spring @Component @Scope("singleton") 公共类 BootStrapper 实现 ApplicationListener<ContextStartedEvent> {
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/15271019/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
@Component @Scope("singleton") public class BootStrapper implements ApplicationListener<ContextStartedEvent> {
提问by Chandana Sapparapu
I am trying to do a one time initialization of my webapp. I need a singleton for the ApplicationListener class, so I set the scope to Singleton, but it is creating multiple instances. This BootStrapper is not defined in any other xml config files. I know that the default scope is singleton, but had to add @Scope("singleton") because it was not a singleton. Even with this annotation, it still creates multiple instances. Here is my ApplicationListener.
我正在尝试对我的 webapp 进行一次初始化。我需要 ApplicationListener 类的单例，所以我将范围设置为单例，但它正在创建多个实例。此 BootStrapper 未在任何其他 xml 配置文件中定义。我知道默认范围是单例，但必须添加 @Scope("singleton") 因为它不是单例。即使有了这个注解，它仍然会创建多个实例。这是我的 ApplicationListener。
@Component
@Scope("singleton")
public class BootStrapper implements ApplicationListener<ContextRefreshedEvent> {
Am I missing anything?
我错过了什么吗？
回答by Ralph
To have a callback that is invoked after the bean is initialized, use @PostConstruct.
要在 bean 初始化后调用回调，请使用@PostConstruct.
@Component
public class BootStrapper() {
@PostConstruct
public void doSomething() {
System.out.println("I am initalized!");
}
}
回答by Nadhu
Try like this:
像这样尝试：
@Configuration
public class TestService
{
private Properties properties;
@Bean
@Scope(value = ConfigurableBeanFactory.SCOPE_SINGLETON)
public Properties getAppProperties()
{
try
{
if (properties == null)
{
properties = ServiceUtils.loadProperties();
}
return properties;
}
catch (Exception e)
{
LOGGER.logCaughtException("Exception Occured while loading App Properties.", e);
}
}
}
