Introduction 介绍

The Interface Segregation principle states that no implementation of an interface should be forced to depend on methods it does not use. Have you ever had to implement methods of an interface that you did not need? If so, you probably created blank methods in your implementation. This is an example of being forced to use an interface that breaks the Interface Segregation principle.

接口隔离原则规定在实现接口的时候，不能强迫去实现没有用处的方法。你是否曾被迫去实现一些接口里你用不到的方法？如果答案是肯定的，那你可能创建了一个空方法放在那里。被迫去实现用不到的函数，这就是一个违背了接口隔离原则的例子。

In practical terms, this principle demands that interfaces be granular and focused. Sound familiar? Remember, all five SOLID principles are related, such that by breaking one you often must break the others. When breaking the Interface Segregation principle, the Single Responsibility principle must also broken.

在实际操作中，该原则要求接口必须粒度很细，且专注于一个领域。听起来很耳熟？记住，所有五个“坚实”原则都是相关的，也就是说当打破一个原则时，你通常肯定打破了其他的原则。在这里当你违背了接口隔离原则后，肯定也违背了单一职责原则。

Instead of having a "fat" interface containing methods not needed by all implementations, it is preferable to have several smaller interfaces that may be implemented individually as needed. By breaking fat interfaces into smaller, more focused contracts, consuming code can depend on the smaller interface, without creating dependencies on parts of the application it does not use.

“臃肿”的接口，有着很多不是所有的实现类都需要的方法。与其写这样的接口，不如将其拆分成多个小巧的接口，里面的方法都是各自领域所需要的。这样将臃肿接口拆成小巧、功能集中的接口后，我们就可以使用小接口来编码，而不必为我们不需要的功能买单。

Interface Segregation Principle 接口隔离原则

This principle states that no implementation of an interface should be forced to depend on methods it does not use.

该原则规定，一个接口的一个实现类，不应该去实现那些自己用不到的方法。如果需要，那就是接口设计有问题，违背了接口隔离原则。