什么是Apache License 2.0开源协议
Apache License 2.0协议来自于著名的Apache基金会，其最重要的开源软件就是Apache（HTTPD）网站服务器。
Apache License协议和BSD类似，同样鼓励代码共享和尊重原作者的著作权，同样允许代码修改，再发布（作为开源或商业软件）。需要满足的条件也和BSD类似：
- 需要给代码的用户一份Apache Licence
- 如果你修改了代码，需要在被修改的文件中说明
- 在延伸的代码中（修改和有源代码衍生的代码中）需要带有原来代码中的协议，商标，专利声明和其他原来作者规定需要包含的说明。
- 如果再发布的产品中包含一个Notice文件，则在Notice文件中需要带有Apache Licence。你可以在Notice中增加自己的许可，但不可以表现为对Apache Licence构成更改。
Apache Licence也是对商业应用友好的许可。使用者也可以在需要的时候修改代码来满足需要并作为开源或商业产品发布/销售。著名的Android系统，Apache基金会的众多开源项目，Swift项目等，都是用Apache Lincese 2.0协议。
使用Apache Licence 2.0协议的好处是:
- 永久权利，一旦被授权，永久拥有。
- 全球范围的权利，在一个国家获得授权，适用于所有国家。假如你在美国，许可是从印度授权的，也没有问题。
- 授权免费无版税， 前期、后期均无任何费用。
- 授权无排他性，任何人都可以获得授权
- 授权不可撤消，一旦获得授权，没有任何人可以取消。比如，你基于该产品代码开发了衍生产品，你不用担心会在某一天被禁止使用该代码。
Apache Lincese 2.0协议的英文原文Apache Lincese 2.0协议的英文原文： Apache License Version 2.0, January 2004 http://www.apache.org/licenses/ TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 1. Definitions. "License" shall mean the terms and conditions for use, reproduction, and distribution as defined by Sections 1 through 9 of this document. "Licensor" shall mean the copyright owner or entity authorized by the copyright owner that is granting the License. "Legal Entity" shall mean the union of the acting entity and all other entities that control, are controlled by, or are under common control with that entity. For the purposes of this definition, "control" means (i) the power, direct or indirect, to cause the direction or management of such entity, whether by contract or otherwise, or (ii) ownership of fifty percent (50%) or more of the outstanding shares, or (iii) beneficial ownership of such entity. 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