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This article introduces you what is the principle of Lombok, the content is very detailed, interested friends can refer to, hope to be helpful to you.

Take idea as an example, search for the Lombok plug-in directly in the tool, and then install it. Restart the idea development tools after the installation is complete.

Next, we need to introduce Lombok's jar package into projects that use Lombok. The following configurations are introduced into the POM.xml of Maven:

Then the get/set in the project can be replaced by the following code:

Lombok has a lot of comments, and the following is an explanation of these notes.

Lombok's val may be used by fewer people, but it is actually the most recommended one, a JavaScript-like val.

The use of @ NonNull is also common.

@ Cleanup closes the stream.

The use of @ ToString

The use of @ EqualsAndHashCode

The most common use of @ Data.

There is also the most common use of @ Builder.

For more information about the use of Lombok annotations, I will not enumerate them one by one. You can take a look at the note above.

Finally, I would like to talk about the principle of Lombok. Through its annotations, we can see that Lombok annotations all define the code with @ Retention as RetentionPolicy.RUNTIME. In this way, it can only get the annotation value through reflection at run time, which reduces the efficiency of the runtime code. Second, if you want to use annotations to do some checking during the compilation phase and report errors in some of the user's unreasonable code, the use of reflection is powerless. Fortunately, we now have JSR 269, which allows us to do these things with annotations at compile time of Javac. So we found that the core distinction is at run time or compile time.

In the Lombok process, after the Javac is parsed into an abstract syntax tree (AST), Lombok dynamically modifies the AST according to its own annotation processor, adds new nodes (so-called code), and finally analyzes and generates bytecode.

Since Java 6, javac has supported the "JSR 269 Pluggable Annotation Processing API" specification, and as long as the program implements the API, it can be called when the javac is running.

About what the principle of Lombok is shared here, I hope that the above content can be of some help to you, can learn more knowledge. If you think the article is good, you can share it for more people to see.

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