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This article mainly explains "JAVA decorator pattern application example analysis", interested friends may wish to have a look. The method introduced in this paper is simple, fast and practical. Now let the editor to take you to learn "JAVA decorator pattern application example analysis" it!

What is the decorator mode?

Definition of Decorator pattern: a pattern that dynamically adds some responsibilities (that is, additional functions) to the object without changing the existing object structure, which belongs to the object structure pattern.

Advantages

1. The decorator is a powerful supplement to inheritance, which is more flexible than inheritance. It dynamically extends the function of an object, namely plug and play, without changing the original object.

2. Different effects can be achieved by using non-decorative classes and the arrangement and combination of these decorative classes.

3. The decorator mode fully obeys the principle of opening and closing.

Shortcoming

The decorator pattern adds many subclasses, and overuse will increase the complexity of the program.

Knowledge point

In general, the ability to extend a class is implemented by inheritance. But inheritance has static characteristics, high coupling, and with the increase of extended functions, the subclasses will be very inflated. If you use a composite relationship to create a wrapper object (that is, a decoration object) to wrap the real object and provide it with additional functionality while keeping the class structure of the real object unchanged, this is the goal of the decorator pattern. The following is to analyze its basic structure and implementation method.

Decorator pattern implementation

Case study: the Black Tiger caught the Seven and roasted the rainbow cat.

Abstract component (Component) roles: seven

Concrete component (ConcreteComponent) role: rainbow cat

Abstract Decoration (Decorator) characters: feeding

Specific decoration (ConcreteDecorator) role: add salt, add cumin.

The Seven

Seven interface, declaring an abstract method of barbecue

Public interface Qi {void show ();} rainbow cat

The rainbow cat class implements the seven-man interface and realizes the method of roasting the rainbow cat.

Public class Hong implements Qi {@ Override public void show () {System.out.println ("barbecue a rainbow cat");}} add ingredients

This is an abstract decorator that implements the seven-man interface, declares a seven-man attribute, and invokes the seven-man barbecue method.

Public class JiaLiao implements Qi {private Qi qi; JiaLiao () {} JiaLiao (Qi component) {this.qi = component;} @ Override public void show () {qi.show ();}} add salt

Inherited the abstract class, and rewrote the barbecue method, adding a salt

Public class Yan extends JiaLiao {private Qi qi; Yan () {} Yan (Qi qi) {super (qi);} @ Override public void show () {super.show (); add ();} public void add () {System.out.println ("salt");}} cumin

Inherited the abstract class and rewrote the barbecue method, adding an cumin

Public class ZiRan extends JiaLiao {private Qi qi; ZiRan () {} ZiRan (Qi qi) {super (qi);} @ Override public void show () {super.show (); add ();} public void add () {System.out.println ("Ghazi");}} Test

New a rainbow cat, roast it.

Add some salt

Add some salt and cumin

Public class Demo {public static void main (String [] args) {Qi qi = new Hong (); qi.show (); System.out.println (); Qi qi1 = new Yan (qi); qi1.show (); System.out.println (); Qi qi2 = new ZiRan (qi1); qi2.show ();}}

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