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Spring - 注入 java.util 类

[英]Spring - injection java.util classes

原文 2018-03-03 23:29:13 5 1 java/ spring

I'm working on java.util classes injection, with Spring.我正在使用 Spring 进行 java.util 类注入。

I wonder, do you register your bean classes like Scanner or Random in Spring's context?我想知道，您是否在 Spring 的上下文中注册了像Scanner或Random这样的 bean 类？

I guess this decision depends on how often you will use it, right?我想这个决定取决于你使用它的频率，对吗？

What is the number of usages when I should consider returning bean instead of creating a new object?当我应该考虑返回 bean 而不是创建新对象时，使用次数是多少？

1 个解决方案

Do you want multiple beans to share a single source of random numbers?您是否希望多个 bean 共享一个随机数源？ If so, then the beans needs to be injected with a random number generator bean.如果是这样，则需要使用随机数生成器 bean 注入 bean。

It is however recommended to use ThreadLocalRandom in a multi-threaded program (for better performance), and it doesn't hurt in a single-threaded program, so general recommendation is to use that, which means Random should never be a Spring bean.然而，建议在多线程程序中使用ThreadLocalRandom （以获得更好的性能），并且它在单线程程序中不会受到伤害，所以一般建议使用它，这意味着Random永远不应该是 Spring bean。

However, if you need to unit test code, using a seeded random number sequence, then code needs to be injected with a random number bean that can be mocked.但是，如果您需要使用种子随机数序列对代码进行单元测试，则需要将代码注入可以模拟的随机数 bean。

Note however, that such random number bean is not the Random class itself, but a wrapper/helper bean.但是请注意，这种随机数 bean 不是Random类本身，而是一个包装器/帮助器 bean。

Do you want multiple beans to share a single Scanner ?你想让多个 bean 共享一个Scanner吗？

That question really only makes sense in a command-line program, reading System.in , in which case answer is yes.这个问题只有在命令行程序中才有意义，阅读System.in ，在这种情况下答案是肯定的。