Detailed explanation of PHP5 object-oriented interface technology

PHP 5 also supports the concept of interfaces and introduces the interface and implements keywords. Like Java, PHP 5 uses interfaces to achieve an effect similar to "multiple inheritance".

PHP5 interface syntax is as follows:
When declaring a class, we use the keyword "class", and the interface, a special class, uses the keyword "interface";

Class definition: class class name {…}, interface declaration: interface interface name {…}

The code of the specific PHP5 abstract class is as follows:

The code is as follows

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代码如下

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abstract class AbstractClass {

abstract public function test();

}

class ImplementedClass extends AbstractClass {

public function test() {

echo "ImplementedClass::test() called. ";

}

$o = new ImplementedClass;

$o->test();

abstract class AbstractClass {

abstract public function test();

代码如下

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interface displayable {

function display();

}

interface printable {

function doprint();

}

class foo implements displayable,printable {

function display() {

// code

} function doprint() {

// code

}

class ImplementedClass extends AbstractClass {

代码如下

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interface One
{
//定义一个常量
const constant = 'constant value';

//定义了一个抽象方法”fun1”
public function fun1();

//定义了抽象方法”fun2”
public function fun2();
}

public function test() { echo "ImplementedClass::test() called. "; } } $o = new ImplementedClass; $o->test();

Example 2

The code is as follows	Copy code
interface displayable { function display(); } interface printable { function doprint(); } class foo implements displayable,printable { function display() { // code } function doprint() { // code } }

The introduction of abstract classes and PHP5 interfaces makes PHP a completely object-oriented language //Define an interface using the interface keyword, "One" is the interface name

The code is as follows	Copy code
interface One { //Define a constant const constant = 'constant value'; //An abstract method "fun1" is defined Public function fun1(); //Abstract method "fun2" is defined Public function fun2(); }

In the above example, an interface "one" is defined, which declares two abstract methods "fun1" and "fun2". Because all methods in the interface are abstract methods, there is no need to declare abstract methods like Abstract classes use the "abstract" keyword like this. This keyword has been added by default. In addition, the "public" access permission in the interface can also be removed, because the default is public, because all members in the interface must be public. Yes, we cannot use "private" and "protected" permissions for members in the interface. We must use public or default. In addition, we also declared a constant "constant" in the interface. Because variable members cannot be used in the interface, we have to use the const keyword declaration.

Because the interface is a special abstract class, all methods in it are abstract methods, so the interface cannot produce instance objects; it is also a specification that all abstract methods need to be implemented by subclasses.

We can use the "extends" keyword to let one interface inherit another interface;

The code is as follows

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代码如下	复制代码
//使用”extends”继承另外一个接口 interface Two extends One { function fun3(); function fun4(); }

//Use "extends" to inherit another interface
interface Two extends One
{
Function fun3();
Function fun4();
}

When we define a subclass of an interface to implement all the abstract methods in the interface, the keyword used is "implements" instead of "extends" as we mentioned before;

//Use the keyword "implements" to implement the abstract methods in the interface

代码如下

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class Three implements One
{
    function fun1()
    {
        … …
    }

    function fun2()
    {
        … …
    }
}

The code is as follows

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class Three implements One
{
Function fun1()
{
… …
}

代码如下	复制代码
$three=new Three();

function fun2()
{
… …
}
}

//With all methods implemented, we can use subclasses to instantiate objects

代码如下	复制代码
//使用implements实现多个接口 class Four implemtns 接口一，接口二，…… { //必须把所有接口中的方法都要实现才可以实例化对象。 }

We can also use abstract classes to implement some abstract methods in the interface, but in order to instantiate an object, this abstract class must have a subclass to implement all its abstract methods; As we said before, PHP has single inheritance. A class can only have one parent class, but a class can implement multiple interfaces, which is equivalent to a class having to comply with multiple specifications, just like we must not only comply with national If you are in school, you must also abide by the school's school rules;

The code is as follows	Copy code
//Use implements to implement multiple interfaces class Four implemtns interface one, interface two,... { //All methods in the interface must be implemented before the object can be instantiated. }

In PHP, not only one class can implement multiple interfaces, but you can also implement multiple interfaces while inheriting a class. You must first inherit the class and then implement the interface;

The code is as follows

代码如下	复制代码
//使用extends继承一个类，使用implements实现多个接口 class Four extends 类名一 implemtns 接口一，接口二，…… { //所有接口中的方法都要实现才可以实例化对象 ……… }

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//Use extends to inherit a class and implements to implement multiple interfaces
class Four extends class name one implemtns interface one, interface two,...

{

代码如下	复制代码
interface VideoCardInter{ function Display(); function getName(); } ?>

//All methods in the interface must be implemented before the object can be instantiated

………

}

代码如下	复制代码
include_once("VideoCard.php"); class Dmeng implements VideoCardInter { function Display(){ echo "Display"; } function getName(){ return "Dmeng VideoCard"; } } ?>

代码如下	复制代码
include_once("VideoCard.php"); include_once("Dmeng.php"); class Mainboard{ var $vc; function run(VideoCardInter $vc){ //定义VideoCardInter接口类型参数，这时并不知道是谁来实现。 $this->vc=$vc; $this->vc->Display(); echo "主板运行！"; } } $conputer=new Mainboard(); $conputer->run(new Dmeng);

After talking so much, let’s take a look at an example

VideoCard.php interface file (functional interface definition of graphics card)

The code is as follows

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interface VideoCardInter{

function Display();

function getName();

}

Dmeng.php implements the interface (the manufacturer of Dmeng implements these interfaces, the motherboard manufacturer does not have to worry about how to implement it)

Detailed explanation of PHP5 object-oriented interface technology_PHP tutorial