这是什么意思以及如何修复 SonarQube Java 问题“应删除包之间的循环"；(鱿鱼:CycleBetweenPackages) [英] What does it mean and how to fix SonarQube Java issue "Cycles between packages should be removed" (squid:CycleBetweenPackages)

问题描述

当这些包中的类之间存在使用或导入种类的依赖时，包之间存在循环.

Cycles exist between packages when there are dependencies of using or importing kind between classes in these packages.

考虑以下示例.让有 4 个类:Truck 和 Car 接口在 org.example.car 包和 Navigation 和 >CPU 在包 org.example.part 中.在包 org.example.car 和 org.example.part 中，我们使用了类 Truck --> 之间的关系.汽车和类Navigation -->CPU.让我们假设 Truck 类使用 Navigation 类，所以我们有数据包之间的关系 org.example.car -->org.example.part.然后假设CPU类也使用了Car接口，这给了我们包org.example.part -->org.example.car.尽管 Navigation 类不使用任何包 org.example.car 类，但我们在包中的相邻类上有一个循环(CPU 类).

Consider the following example. Let there be 4 classes: Truck and interface Car in org.example.car package and Navigation and CPU in package org.example.part. In packages org.example.car and org.example.part we have use relations between classes Truck --> Car and classes Navigation --> CPU. Let's assume that the class Truck use Navigation class so we have the relationship between packets org.example.car --> org.example.part. Then assume that the class CPU also uses the Car interface, which gives us the relationship between packages org.example.part --> org.example.car. Although the class Navigation does not use any class of packet org.example.car we have a cycle on neighboring classes in packages (CPU class).

这个例子如下图所示:

alt-cycles-in-packages-example.svg-cycles

当一个循环中涉及多个包时，这意味着这些包是高度耦合的，如果不导入所有其他包，就无法重用/提取其中一个包.这样的循环可能会迅速增加维护应用程序和接受业务变化所需的工作量.

When several packages are involved in a cycle, that means those packages are highly coupled, and there is no way to reuse/extract one of those packages without importing all the other packages. Such cycle could quickly increase the effort required to maintain an application and embrace business change.

推荐答案

要修复包中的依赖循环，您应该引入额外的包并将几个依赖类/接口移动到新创建的包中.

To fix dependency cycle in your packages you should introduce additional package and move couple of dependent classes/interfaces to that newly created package.

如下图所示:

a

在我们的示例中，让我们选择将接口 Car 移动到新创建的包 org.example.api.这打破了依赖循环并降低了我们应用程序中的技术深度.现在所有包都只有一种依赖关系，如果需要，可以将它们拆分为不同的工件.

In our example, let us chose to move interface Car to newly created package org.example.api. That breaks the dependency cycle and lowers technical dept in our application. Now all packages have dependencies in only one way and it is possible to split them in different artifacts if needed.

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