php studies the application of [interfaces] and [polymorphism] in object orientation

 
<?php 
/*  Interface technology  
* 
*  Interface is 1 A special abstract class , Again, the abstract class 1 A special class  
* 
*  Interfaces and abstract classes are 1 The role of the sample  
* 
*  Because in the PHP Is a single inheritance, if the use of abstract class, the subclass implementation of the abstract class can no longer inherit other classes  
* 
*  If you want to do it 1 They want to inherit from other classes. You use interfaces.  
* 
*  Interface versus abstract classes  
* 
* 1. It does the same thing, you can't create an object, you have to subclass it  
* 
* 2. Interface declarations and abstract classes are not 1 sample  
* 
* 3. The interface is implemented in a way that is not 1 sample  
* 
* 4. All methods in an interface must be abstract methods , Only abstract methods can be declared ( Don't use abstract modified ) 
* 
* 5. Member properties in the interface, can only declare constants, not variables  
* 
* 6. Member access in the interface must be public, Lowest permission in an abstract class protected 
* 
*  Declaration interface:  interface  The interface name { }; 
* 
* 7. use 1 Class to implement the interface, not to use extends, It USES implements The keyword  
* 
*  If the subclass overrides an abstract method in the parent interface implements( implementation ), class -- Interface, abstract class -- interface   use implements , the interface -- interface   use extends( inheritance ) 
* 
*  You can use an abstract class to implement some of the methods in the interface  
*  If you want subclasses to be able to create objects, you must implement all the methods in the interface  
*  It is possible to define 1 Interface to inherit another 1 An interface  
* 1 Classes can implement multiple interfaces ( Subclass by multiple specifications ), Separate multiple interface names with commas  
* 1 Classes can be inherited 1 At the same time, to implement 1 Two or more interfaces  
* 
*  use implements For two purposes:  
* 
* 1. Can implement multiple interfaces while extends Words can only be inherited 1 A parent class  
* 
* 2. Don't use extends Words can be inherited 1 Class, so both can be used at the same time  
* 
*  Polymorphism: polymorphism is object-oriented 3 Of the characteristics of the large 1 
* 
*  "Polymorphism" is an important feature of object-oriented design that exhibits dynamic binding ( dynamic binding ), also known as "namesake" ( Polymorphism ). The polymorphic functionality enables software to be developed and maintained with sufficient extensibility ( extension ). In fact, the most straightforward definition of polymorphism is that different classes of objects with inheritance can call member functions of the same name and have different effects.  
* 
* 
* 
* 
* 
*/ 
// The statement interface  
interface Demo{ 
const HOST="localhost"; 
const USER="admin"; 
function fun1();// Declare methods without adding abstract By default. Permissions are public 
function fun2(); 
} 
// Inheritance of interface  
interface Demo2 extends Demo { 
function fun3(); 
function fun4(); 
} 
interface Demo3{ 
function fun5(); 
function fun6(); 
} 
interface Demo4{ 
function fun7(); 
} 
echo Demo::HOST;// You can access constants in the interface  
class Hello{ 
function fun8(){ 
} 
} 
// Subclasses must implement all methods in the interface  
class UTest extends Hello implements Demo2,Demo3,Demo4 { // Implement multiple interfaces  
function fun1(){ 
} 
function fun2(){ 
} 
function fun3(){ 
} 
function fun4(){ 
} 
function fun5(){ 
} 
function fun6(){ 
} 
function fun7(){ 
} 
} 
/*------------------- polymorphism ---------------*/ 
interface Test{ 
function fun1(); 
function fun2(); 
} 
class One implements Test{ 
function fun1(){ 
echo "aaaaaaaaa"; 
} 
function fun2(){ 
echo "bbbbbbbbbbbb"; 
} 
} 
class Two implements Test{ 
function fun1(){ 
echo "11111111"; 
} 
function fun2(){ 
echo "2222222222"; 
} 
} 
// with 1 Interface, with the implementation 1 Methods, different objects, different output. This is the manifestation and application of polymorphism  
$test=new One; 
$test->fun1();// The output 1 line  a 
$test->fun2();// The output 1 line  b 
$test=new Two; 
$test->fun1();// The output 1 line  1 
$test->fun2();// The output 1 line  2 
?> 
<?php 
/*-------------- Polymorphism of the 1 Application examples   simulation USB Use of equipment ------------------*/ 
//1 a USB The interface of the  
interface USB{ 
function mount();// loading USB The method of  
function work();//USB Method of work  
function unmount();// uninstall USB The method of  
} 
// define 1 a USB equipment  U disc  
class Upan implements USB{// implementation USB interface  
function mount(){ 
echo " U disc   Load the success <br/>"; 
} 
function work(){ 
echo "U disc   Start to work <br/>"; 
} 
function unmount(){ 
echo "U disc   Uninstall the success <br/>"; 
} 
} 
// define 1 a USB equipment  USB The mouse  
class Umouse implements USB{// implementation USB interface  
function mount(){ 
echo " USB The keyboard   Load the success <br/>"; 
} 
function work(){ 
echo "USB The keyboard   Start to work <br/>"; 
} 
function unmount(){ 
echo "USB The keyboard   Uninstall the success <br/>"; 
} 
} 
// define 1 A computer class  
class Computer{ 
// use USB Method of equipment  
function useUSB ($usb){//$usb parameter   Use which USB equipment  
$usb->mount();// Calling device's   Loading method  
$usb->work();// Calling device's   Working methods  
$usb->unmount();// Invokes the device's unload method  
} 
} 
// define 1 Class of computer users  
class PcUser{ 
// The installation USB The method of  
function install(){ 
// First of all to 1 computer  
$pc=new Computer; 
// it 1 some USB equipment  
$up=new Upan;// it 1 a U disc  
$um=new Umouse;// it 1 a USB The mouse  
// the USB Device plugged into computer ,  Use in computer USB Method of equipment   To invoke the   The device to plug in  
$pc->useUSB($up);// insert U disc  
$pc->useUSB($um);// insert USB The mouse  
} 
} 
// instantiation 1 Personal computer users  
$user=new PcUser; 
$user->install();// Install the equipment  
/*------------- output -------------- 
U disc   Load the success  
U disc   Start to work  
U disc   Uninstall the success  
USB The keyboard   Load the success  
USB The keyboard   Start to work  
USB The keyboard   Uninstall the success  
-----------------------------------*/ 
?> 

Author: code name aurora
http://www.cnblogs.com/zizhuyuan/archive/2011/06/16/2082262.html