【转】PHP透过接口实现多重继承

【转】PHP通过接口实现多重继承

PHP类虽然是单继承的，但是可以通过其它特殊的方式实现多重继承，比如使用接口实现，只要把类的特征抽象为接口，并通过实现接口的方式让对象有多重身 份，通过这样就可以模拟多重继承了。

下面就是一个用接口模拟多重继承的例子，源代码如下：

<? ?interface?UserInterface{?// 定义User的接口 ??function?getname(); ?} ?interface?TeacherInterface{?//teacher 相关接口 ??function?getLengthOfService(); ?} ?class?User?implements?UserInterface?{?// 实现UserInterface接口 ??private?$name?=?"tom"; ??public?function?getName(){ ???return?$this->name; ??} ?} ?class?Teacher?implements?TeacherInterface?{?// 实现TeacherInterface接口 ??private?$lengthOfService?=?5;?//?工 龄? ??public?function?getLengthOfService(){ ???return?$this->lengthOfService; ??} ?} ?//?继承自User类,同时实现了 TeacherInterface接口. ?class?GraduateStudent?extends?User?implements?TeacherInterface?{ ??private?$teacher?; ??public?function?__construct(){ ???$this->teacher?=?new?Teacher();?? ??}? ??public?function?getLengthOfService(){ ???return?$this->teacher->getLengthOfService(); ??} ?} ?class?Act{ ??//注意这里的类型提示改成了接口类型 ??public?static?function?getUserName(UserInterface?$_user){ ???echo?"Name?is?"?.?$_user->getName()?."<br>"; ??} ??//这里的类型提示改成了 TeacherInterface类型. ??public?static?function??getLengthOfService(TeacherInterface?$_teacher){ ???echo?"Age?is?"?.$_teacher->getLengthOfService()?."<br>"; ??} ?} ?$graduateStudent?=?new?GraduateStudent(); ?Act::getUserName($graduateStudent); ?Act::getLengthOfService($graduateStudent); ?//结果正如我们所要的,实现了有多重身份的一个对象. ??>?

示例运行结果如下：

Name is tom

Age is 5