ApplicationContextAware如何在Spring中运行？ [英] How does ApplicationContextAware work in Spring?

问题描述

在spring中，如果bean实现了 ApplicationContextAware ，那么它就能够访问 applicationContext 。因此它能够获得其他豆类。
，例如

In spring, if a bean implements ApplicationContextAware, then it is able to access the applicationContext. Therefore it is able to get other beans. e.g.

public class SpringContextUtil implements ApplicationContextAware {
    private static ApplicationContext applicationContext;     

    public void setApplicationContext(ApplicationContext context) throws BeansException {
      applicationContext = context;
    }

    public static ApplicationContext getApplicationContext() {
      return applicationContext;
    }
}

然后 SpringContextUtil.getApplicationContext。 getBean（name）可以得到beanname。

Then SpringContextUtil.getApplicationContext.getBean("name") can get the bean "name".

为此，我们应该把这个 SpringContextUtil 在 applications.xml 中，例如

To do this, we should put this SpringContextUtil inside the applications.xml, e.g.

<bean class="com.util.SpringContextUtil" />

此处bean SpringContextUtil 不包括属性 applicationContext 。我想当spring bean初始化时，会设置此属性。但这是怎么做到的？如何调用方法 setApplicationContext ？

Here the bean SpringContextUtil doesn't include the property applicationContext. I guess when spring bean initialize, this property is set. But how is this done? How does the method setApplicationContext get called?

推荐答案

当spring实例化bean时，它寻找几个接口，如 ApplicationContextAware 和 InitializingBean 。如果找到它们，则调用这些方法。例如。 （非常简化）

When spring instantiates beans, it looks for a couple of interfaces like ApplicationContextAware and InitializingBean. If they are found, the methods are invoked. E.g. (very simplified)

Class<?> beanClass = beanDefinition.getClass();
Object bean = beanClass.newInstance();
if (bean instanceof ApplicationContextAware) {
    ((ApplicationContextAware) bean).setApplicationContext(ctx);
}

请注意，在较新的版本中，最好使用注释，而不是实施特定于弹簧的接口。现在你只需使用：

Note that in newer version it may be better to use annotations, rather than implementing spring-specific interfaces. Now you can simply use:

@Inject // or @Autowired
private ApplicationContext ctx;

这篇关于ApplicationContextAware如何在Spring中运行？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！