如果一个bean试图在它的构造函数中加载Spring应用程序上下文，会发生什么？ [英] What happens if a bean attempts to load the Spring application context in its constructor?

问题描述

给定以下Spring应用程序上下文和类A，当您运行类A时会发生什么？

Given the following Spring application context and class A, what happens when you run class A?

applicationContext.xml（在类路径中）：

applicationContext.xml (in classpath):

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans-2.5.xsd">
    <bean name="a" class="A"/>
</beans>

A.java：

class A {
    private ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");

    public static void main(String[] args) {
        A a = new A();
    }
}

推荐答案

不质疑你的方法，但为什么这是必要的？如果一个bean想要一个指向应用程序上下文的指针，它是它的一部分，它应该实现 ApplicationContextAware 。你将实现一个setter，Spring会将应用上下文注入到bean中。

Not to question your approach, but why is this necessary? If a bean wants a pointer to the application context it's a part of, it should implement ApplicationContextAware. You'll implement a setter and Spring will inject the app context into the bean.

除非我错了，你的示例代码实际上不会给这个bean一个指针到其应用上下文，它将使用与以前相同的XML文件启动一个新的应用上下文。这将反过来创建一个新的bean，它将启动另一个应用程序上下文等等 - 一个无限循环。试试您的代码，看看是否会发生这种情况。

Unless I'm mistaken, your sample code won't actually give that bean a pointer to its app context, it will start up a new app context using the same XML file as before. This will in turn create a new bean, which will start another app context, etc. — an infinite loop. Try out your code and see whether this happens.

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