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Editor to share with you springboot access tool class bean process example analysis, I believe that most people do not know much about it, so share this article for your reference, I hope you will learn a lot after reading this article, let's go to know it!

The reason for this practical experience is that, in development, I want to use the variable value of the configuration file in the tool class. The @ value annotation is usually used, which can only be obtained by bean managed in spring. I also wondered why previous developers added @ Component annotations to the SpringUtil class, but today I fully understand why this is the case.

@ Componentpublic class SpringUtil implements EnvironmentAware {private static Environment env; public static String getProperty (String key) {return env.getProperty (key);} @ Override public void setEnvironment (Environment environment) {injectEnvironment (env); / / because spring creates an object of the implementation class of this interface, the instance method calls the static method, but we can't see this class at present.} public static void injectEnvironment (Environment env) {SpringUtil.env = env / / this is actually an instance method calling a static method}}

The principle is very simple, that is, instance methods call static methods, so objects are generated, only one utility class object is produced, not many, which is very java, very spring. Accordingly, the @ Service annotation is also a singleton (this should be based on the fact that the method is naturally parallel, and each time the method is called, it will generate its own data stack). You can also see that it is appropriate to use objects in this spring, and the overhead of creating objects can be ignored.

Learning spring, we all know that one of the important functions of spring is object management. So an important question is: how do we get the Bean we want? Is there a static class in spirng that gets the object directly by name?

Sorry, this is not the right way to open spring, although it is straightforward to use static classes, but spring does not do so. The usual practice is to inject the ApplicationContext object through spirng, which is a bean container, and then we can get the class we want. I'm sorry, you can't new an ApplicationContext object yourself, which may be to keep only one ApplicationContext object in the runtime environment.

A single case is a kind of concise beauty. As for why singletons are used instead of static classes, I think there are two reasons:

1. The creation and destruction of singletons can save resources when not in use.

two。 Most of the classes we inherit are instance methods and instance variables (as for why most classes should be instantiated, and there may be multiple objects), then inheritance is instance methods and instance variables, which can be said to be the influence of object-oriented programming style in singleton cases. The drawback of singletons may be the overhead of generating objects, which is nothing now.

The above is all the contents of the article "sample Analysis of the bean process of springboot getting tools". Thank you for reading! I believe we all have a certain understanding, hope to share the content to help you, if you want to learn more knowledge, welcome to follow the industry information channel!

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