不久前，我看到这里回答了一个关于Java包的细粒度组织的问题。例如，my.project。my.project跑龙套。工厂,my.project。服务等。
在Java中有关于包组织的最佳实践吗?它们包含什么?
如何在Java项目中组织类?
For instance, a project I'm working on with a few people has a package called beans. It started out being a project containing simple beans, but it has ended up (through poor experience and lack of time) containing everything (almost). I've cleaned them up a little, by putting some factory classes in a factory package (classes with static methods that create beans), but we have other classes that do business logic and others that do simple processing (not with business logic) like retrieving a message for a code from a properties file.
我见过一些人提倡“按功能打包”而不是“按层打包”，但多年来我使用了不少方法，发现“按层打包”比“按功能打包”要好得多。
此外，我还发现了一种混合策略:“按模块打包，层然后功能”策略在实践中效果非常好，因为它具有“按功能打包”的许多优点:
促进可重用框架(具有两种模型的库)的创建
和用户界面方面)
允许即插即用层实现——“按特性包”几乎不可能实现，因为它将层实现放在与模型代码相同的包/目录中。
更多的……
我在这里深入解释:Java包的名称结构和组织，但我的标准包结构是:
revdomain moduleName moduleType。层层subfeatureN [layerImpl]。feature。subfeatureN + 1 ...
地点:
revdomain反向域名，如com.mycompany
moduleType(应用程序框架* | | util)
例如，如果模块类型是app，则返回myAppName;如果模块类型是会计框架，则返回'finance'
层[模型|ui|持久化|安全等，]
layerImpl，例如，wicket, jsp, jpa, jdo, hibernate(注意:如果layer是model则不使用)
特征，如金融
例如，会计
subfeatureN+1，例如，折旧
如果moduleType是一个应用程序，有时'app'会被省略，但是把它放在那里可以使所有模块类型的包结构保持一致。
我见过一些人提倡“按功能打包”而不是“按层打包”，但多年来我使用了不少方法，发现“按层打包”比“按功能打包”要好得多。
此外，我还发现了一种混合策略:“按模块打包，层然后功能”策略在实践中效果非常好，因为它具有“按功能打包”的许多优点:
促进可重用框架(具有两种模型的库)的创建
和用户界面方面)
允许即插即用层实现——“按特性包”几乎不可能实现，因为它将层实现放在与模型代码相同的包/目录中。
更多的……
我在这里深入解释:Java包的名称结构和组织，但我的标准包结构是:
revdomain moduleName moduleType。层层subfeatureN [layerImpl]。feature。subfeatureN + 1 ...
地点:
revdomain反向域名，如com.mycompany
moduleType(应用程序框架* | | util)
例如，如果模块类型是app，则返回myAppName;如果模块类型是会计框架，则返回'finance'
层[模型|ui|持久化|安全等，]
layerImpl，例如，wicket, jsp, jpa, jdo, hibernate(注意:如果layer是model则不使用)
特征，如金融
例如，会计
subfeatureN+1，例如，折旧
如果moduleType是一个应用程序，有时'app'会被省略，但是把它放在那里可以使所有模块类型的包结构保持一致。
我不知道包装组织的标准做法。我通常创建的包涵盖一些相当广泛的范围，但我可以在一个项目中进行区分。例如，我目前正在从事的个人项目有一个专门用于定制UI控件的包(充满了派生swing类的类)。我有一个专门用于数据库管理的包，我有一个用于我创建的一组侦听器/事件的包，等等。
On the other hand I've had a coworker create a new package for almost everything he did. Each different MVC he wanted got its own package, and it seemed a MVC set was the only grouping of classes allowed to be in the same package. I recall at one point he had 5 different packages that each had a single class in them. I think his method is a little bit on the extreme (and the team forced him to reduce his package count when we simply couldn't handle it), but for a nontrivial application, so would putting everything in the same package. It's a balance point you and your teammates have to find for yourself.
One thing you can do is try to step back and think: if you were a new member introduced to the project, or your project was released as open source or an API, how easy/difficult would it be to find what you want? Because for me, that's what I really want out of packages: organization. Similar to how I store files in folder on my computer, I expect to be able to find them again without having to search my entire drive. I expect to be able to find the class I want without having to search the list of all classes in the package.
在Java中有关于包组织的最佳实践吗?它们包含什么?
没有，没有。有很多想法，很多观点，但真正的“最佳实践”是运用你的常识!
(请阅读没有最佳实践来了解“最佳实践”和推广它们的人。)
然而，有一个原则可能被广泛接受。你的包结构应该反映你的应用程序的(非正式的)模块结构，你应该尽量减少(或理想情况下完全避免)模块之间的任何循环依赖。
(包/模块中类之间的循环依赖关系很好，但是包之间的循环往往会使理解应用程序的体系结构变得困难，并且可能成为代码重用的障碍。特别是，如果你使用Maven，你会发现循环的包间/模块间依赖关系意味着整个相互连接的混乱必须是一个Maven工件。)
我还应该补充一点，有一个被广泛接受的包名称最佳实践。也就是说，您的包名称应该以您的组织域名的倒序开始。如果你遵循这条规则，你就可以降低你的(完整的)类名与其他人的类名冲突所引起的问题的可能性。
包组织或包结构通常是一个热烈的讨论。下面是一些简单的包命名和结构指南:
Follow Java package naming conventions
Structure your packages according to their functional role as well as their business role
Break down your packages according to their functionality or modules. e.g. com.company.product.modulea
Further break down could be based on layers in your software. But don't go overboard if you have only few classes in the package, then it makes sense to have everything in the package. e.g. com.company.product.module.web or com.company.product.module.util etc.
Avoid going overboard with structuring, IMO avoid separate packaging for exceptions, factories, etc. unless there's a pressing need.
If your project is small, keep it simple with few packages. e.g. com.company.product.model and com.company.product.util, etc.
Take a look at some of the popular open source projects out there on Apache projects. See how they use structuring, for various sized projects.
Also consider build and distribution when naming (allowing you to distribute your API or SDK in a different package, see the servlet API)
经过一些实验和试验，你应该能够提出一个你感到舒服的结构。不要拘泥于一种惯例，要乐于接受改变。
