在java項目中創建package以后，可以在package下放一個package-info.java文件。

這個文件有什么作用？如何生成？

三個作用：

為標注在包上Annotation提供便利；

聲明友好類和包常量；

比如一個包中有很多的內部訪問的類或常量，就可以統一的放到package-info類中，這樣就方便，而且集中管理，減少friendly類到處游走的情況，看例子：

//這里是包類，聲明一個包使用的公共類，強調的是包訪問權限

class PkgClass{

public void test(){

}

}

//包常量，只運行包內訪問，適用于分“包”開發

class PkgConst{

static final String PACAKGE_CONST="ABC";

}

提供包的整體注釋說明。

Package Documentation Prior to Java 5, package level documentation (the documentation shown in Javadocs for a package) was placed in package.html. Today, the description and other related documentation for a package can be written up in the package-info.java file and it gets used in the production of the Javadocs. As a demonstration, the example package-info.java…

/**

* Domain classes used to produce the JSON and XML output for the RESTful services.

*

* These classes contain the JAXB annotations.

*

* @since 1.0

* @author jwhite

* @version 1.1

*/

package com.intertech.cms.domain;

… results in the following Javadocs.

package-info.java’s purpose The package-info.java is a Java file that can be added to any Java source package. Its purpose is to provide a home for package level documentation and package level annotations. Simply create the package-info.java file and add the package declaration that it relates to in the file. In fact, the only thing the package-info.java file must contain is the package declaration.

如何創建：

參考

總結

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