PHP 接口的使用场景，trait的使用

学习总结

• 接口间接实现了多继承
• 接口实现了多态
• trait实现了类中代码的复用

  1.接口可能继承多个接口，类可以继承多个接口

<?php
//类只能单继承，接口允许多继承
interface iSchool
{
    const SCHOOL = '清华大学';
    public function printSchool();
}
interface iDepartment 
{
    const DEPARTMENT = '自动化系';
    public function printDepartment();
}
interface iClass
{
    const CLASSES = '05-01';
    public function printClasses();
}
//类可以继承多个接口
class StuInfo implements iSchool,iDepartment,iClass
{
    protected $name = 'angle';
    protected $age = 32;
    protected $sex = '女';
    public function printSchool()
    {
        echo '校名：',iSchool::SCHOOL,'<br>';
    }
    public function printDepartment()
    {
        echo '系中：',iDepartment::DEPARTMENT,'<br>';
    }
    public function printClasses()
    {
        echo '班名：',iClass::CLASSES,'<br>';
    }
    public function editStuInfo($name,$age,$sex)
    {
        $this ->name = $name;
        $this ->age = $age;
        $this ->sex = $sex;
    }
    public function printStuInfo()
    {
        echo '姓名：',$this ->name,'<br>';
        echo '年龄：',$this ->age,'<br>';
        echo '性别：',$this ->sex,'<br>';
        $this ->printClasses();
        $this ->printDepartment();
        $this ->printSchool();
        echo '<hr>';
    }
}
$stu1 = new StuInfo();
$stu1 -> printStuInfo();
$stu2 = new StuInfo();
$stu2 -> editStuInfo('hugn',31,'男');
$stu2 -> printStuInfo();
?>

• 代码运行结果
  

2.可以用抽象类部分实现接口中的功能，在工作类中再实现接口中的剩余功能

<?php
//可以使用抽象类部分实现接口
interface iPrintInfo
{
    public function editSDCInfo(string $school = '清华大学',string $department = '自动化系',string $classes = '05-01');
    public function printSDCInfo();
}
//抽象类实现了，学校名称，系名，班名的更改，并没有实现打印功能
abstract class aStuInfo implements iPrintInfo
{
    protected $school = '清华大学';
    protected $department = '自动化系';
    protected $classes = '05-01';
    public function editSDCInfo(string $school = '清华大学', string $department = '自动化系', string $classes = '05-01')
    {
        $this -> school = $school;
        $this -> department = $department;
        $this -> classes = $classes;
    }
}
//在工作类中实现学校名称，系名，班名输出
class StuInfo extends aStuInfo
{
    protected $name = 'angle';
    protected $age = 32;
    protected $sex = '女';
    public function editStuInfo($name,$age,$sex)
    {
        $this ->name = $name;
        $this ->age = $age;
        $this ->sex = $sex;
    }
    public function printStuInfo()
    {
        echo '姓名：',$this ->name,'<br>';
        echo '年龄：',$this ->age,'<br>';
        echo '性别：',$this ->sex,'<br>';
        $this ->printSDCInfo();
    }
    //接口中的方法没有在抽象类中实现，在工作类中实现
    public function printSDCInfo()
    {
        echo '班名：',$this ->classes,'<br>';
        echo '系名：',$this ->department,'<br>';
        echo '校名：',$this ->school,'<br>';
        echo '<hr>';
    }
}
$stu1 = new StuInfo();
$stu1 ->printStuInfo();
$stu2 = new StuInfo();
$stu2 ->editStuInfo('hugn',31,'男');
$stu2 -> editSDCInfo('人民大学','工商管理','08-01');
$stu2 ->printStuInfo();
?>

• 代码运行结果
  

3.接口中的构造函数被多个类继承，工作类中可以通过接口访问到每个类中的数据

<?php
interface iSchool
{
    public function __construct();
}
class Qhdx implements iSchool
{
    public $school = null;
    public $department = null;
    public $classes = null;
    public function __construct()
    {
        $this -> school = '清华大学';
        $this -> department = '自动化系';
        $this -> classes = '05-01';
    }
}
class Rmdx implements iSchool
{
    public $school = null;
    public $department = null;
    public $classes = null;
    public function __construct()
    {
        $this -> school ='人民大学';
        $this -> department = '工商管理';
        $this -> classes = '08-02';
    }
}
class StuInfo
{
    protected $name = 'angle';
    protected $age = 32;
    protected $sex = '女';
    public function editStuInfo($name,$age,$sex)
    {
        $this ->name = $name;
        $this ->age = $age;
        $this ->sex = $sex;
    }
    public function printStuInfo()
    {
        echo '姓名：',$this ->name,'<br>';
        echo '年龄：',$this ->age,'<br>';
        echo '性别：',$this ->sex,'<br>';
    }
    //学校，系，班信息为一个对象，iSchool是一个接口，被两个类继承
    public function printSDCInfo(iSchool $sInfo)
    {
        echo '班名：',$sInfo ->classes,'<br>';
        echo '系名：',$sInfo ->department,'<br>';
        echo '校名：',$sInfo ->school,'<br>';
        echo '<hr>';
    }
}
//学校信息通过不同的类实例化而成
$sInfo = new Qhdx;
$stu1 = new StuInfo;
$stu1 ->printStuInfo();
//打印学校信息时，传入的是一个对象
$stu1 ->printSDCInfo($sInfo); 
$sInfo = new Rmdx;
$stu2 = new StuInfo;
$stu2 ->editStuInfo('hugn',31,'男');
$stu2 ->printStuInfo();
$stu2 ->printSDCInfo($sInfo); 
?>

• 代码运行结果
  

4.trait的使用，trait实现类中重复代码的复用

<?php
trait tPrintSDC
{
    public function printSDCInfo()
    {
        echo '班名：',$this ->classes,'<br>';
        echo '系名：',$this ->department,'<br>';
        echo '校名：',$this ->school,'<br>';
        echo '<hr>';
    }
    public function editSDCInfo(string $school = '清华大学', string $department = '自动化系', string $classes = '05-01')
    {
        $this -> school = $school;
        $this -> department = $department;
        $this -> classes = $classes;
    }
}
class StuInfo
{
    use tPrintSDC;
    protected $school = '清华大学';
    protected $department = '自动化系';
    protected $classes = '05-01';
    protected $name = 'angle';
    protected $age = 32;
    protected $sex = '女';
    public function editStuInfo($name,$age,$sex)
    {
        $this ->name = $name;
        $this ->age = $age;
        $this ->sex = $sex;
    }
    public function printStuInfo()
    {
        echo '姓名：',$this ->name,'<br>';
        echo '年龄：',$this ->age,'<br>';
        echo '性别：',$this ->sex,'<br>';
        $this ->printSDCInfo();
    }
}
$stu1 = new StuInfo;
$stu1 ->printStuInfo();
$stu2 = new StuInfo();
$stu2 ->editStuInfo('hugn',31,'男');
$stu2 -> editSDCInfo('人民大学','工商管理','08-01');
$stu2 ->printStuInfo();
?>

• 代码运行结果