为什么要使用@PostConstruct？

问题描述

在受管Bean中，通过bean初始化，而不是常规构造函数本身？

解决方案

因为当构造函数被调用时，bean还没有被初始化 - 即没有注入依赖关系。在 @PostConstruct 方法中，bean被完全初始化，您可以使用依赖关系。

因为是确保在Bean生命周期中仅调用此方法一次的合同。它可能发生（尽管不太可能），bean在其内部工作中被容器多次实例化，但它保证 @PostConstruct 将仅被调用一次。

In a managed bean, @PostConstruct is called after the regular Java object constructor.

Why would I use @PostConstruct to initialize by bean, instead of the regular constructor itself?

解决方案

• because when the constructor is called, the bean is not yet initialized - i.e. no dependencies are injected. In the @PostConstruct method the bean is fully initialized and you can use the dependencies.

• because this is the contract that guarantees that this method will be invoked only once in the bean lifecycle. It may happen (though unlikely) that a bean is instantiated multiple times by the container in its internal working, but it guarantees that @PostConstruct will be invoked only once.

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