What is the use of php interface?

php interface encryption

What is the interface?

Using interface (interface), you can specify which methods a certain class must implement, but you do not need to define the specific content of these methods.

The interface is defined through the interface keyword, just like defining a standard class, but all methods defined in it are empty.

All methods defined in the interface must be public. This is a characteristic of the interface.

When to use interfaces?

1. Set specifications and maintain uniformity;

2. Multiple flat classes need to implement the same method, but in different ways.

Interface usage specifications

1. The interface cannot be instantiated

2. The attributes of the interface must be constants

3.Interface The method must be public [default public], and cannot have a function body

4. The class must implement all methods of the interface

5. A class can implement multiple interfaces at the same time, separated by commas Open

6. The interface can inherit the interface [less used]

interface usb{
    const brand = 'siemens';    // 接口的属性必须是常量
    public function connect();  // 接口的方法必须是public【默认public】，且不能有函数体
}
// new usb();  // 接口不能实例化

// 类实现接口
class Android implements usb{
    public function connect(){  // 类必须实现接口的所有方法
        echo '实现接口的connect方法';
    }
}


interface usbA{
    public function connect();
}

interface usbB{
    public function contact();
}

// 类可以同时实现多个接口
class mi implements usbA,usbB{
    public function connect(){

    }
    public function contact(){

    }
}

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