package-info类解读

最新推荐文章于 2025-02-28 20:46:35 发布

转载最新推荐文章于 2025-02-28 20:46:35 发布 · 389 阅读

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原文链接：http://www.cnblogs.com/extjs4/p/8807882.html

文章标签：

#java #runtime

本文探讨了在Java中如何正确使用package-info.java文件，包括其语法限制和与之相关的javac编译器选项。文章详细解释了三种不同的模式（always、legacy、nonempty），这些模式控制着是否及何时从package-info.java生成package-info.class文件。

类不能带有public、private访问权限。package-info.java再怎么特殊，也是一个类文件，也会被编译成package-info.class，但是在package-info.java中只能声明默认访问权限的类，也就是友好类。

Javac中与package-info相关的命令有：

-Xpkginfo:[always,legacy,nonempty]

Control whether javac generates package-info.class files from package-info.java files. Possible mode arguments for this option include the following.

（1）always

Always generate a package-info.class file for every package-info.java file. This option may be useful if you use a build system such as Ant, which checks that each .java file has a corresponding .class file.

（2）legacy

Generate a package-info.class file only if package-info.java contains annotations. Don't generate a package-info.class file if package-info.java only contains comments.

Note: A package-info.class file might be generated but be empty if all the annotations in the package-info.java file have RetentionPolicy.SOURCE.

（3）nonempty

Generate a package-info.class file only if package-info.java contains annotations with RetentionPolicy.CLASS or RetentionPolicy.RUNTIME.

转载于:https://www.cnblogs.com/extjs4/p/8807882.html