Detailed explanation of JAVA appearance mode

This article brings you relevant knowledge about java, which mainly introduces the relevant content about the appearance mode. The appearance mode is also called the facade mode, which is a method for multiple complex The subsystems provide a consistent interface and make these subsystems more accessible. I hope this will be helpful to everyone.

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Facade mode is also called facade mode, is a pattern that makes multiple complex subsystems more accessible by providing a consistent interface for these subsystems. This mode has a unified interface to the outside world, and external applications do not need to care about the specific details of the internal subsystem. This will greatly reduce the complexity of the application and improve the maintainability of the program.

Advantages

1. Reduces the coupling between the subsystem and the client, so that changes in the subsystem will not affect the client class that calls it.
2. The subsystem components are shielded from customers, reducing the number of objects processed by customers and making the subsystem easier to use.
3. Reduces compilation dependencies in large software systems and simplifies the transplantation process of systems between different platforms, because compiling one subsystem will not affect other subsystems or appearance objects.

Disadvantages

1. It cannot well restrict customers from using subsystem classes, which can easily lead to unknown risks.
2. Adding new subsystems may require modifying the appearance class or client source code, which violates the "opening and closing principle".

Knowledge Points

The structure of the Facade mode is relatively simple, mainly defining a high-level interface. It contains references to various subsystems through which the client can access the functions of each subsystem. Now let’s analyze its basic structure and implementation method.

Appearance mode implementation

Case: The three swords of Changhong Sword, Ice Soul Sword and Ziyun Sword are combined.
Facade role: Three Swords in One
Sub System role: Changhong Sword, Ice Soul Sword, Ziyun Sword
Client role: Test class, call Three Swords in One

Changhong Sword

Changhong Sword class declares a method to call Changhong Sword

public class ChangHong {
    public void show(){
        System.out.println("长虹剑");
    }}

Ice Soul Sword

Ice Soul The sword class declares a method for calling the Ice Soul Sword

public class BingPo {
    public void show(){
        System.out.println("冰魄剑");
    }}

Ziyunjian

The Ziyunjian class declares a method for calling the Ziyunjian

public class ZiYun {
    public void show(){
        System.out.println("紫云剑");
    }}

三剑合璧

Declare three sword objects and declare a method to call the three swords methods.

public class San {
    private ChangHong changHong =new ChangHong();
    private BingPo bingPo=new BingPo();
    private ZiYun ziYun=new ZiYun();
    public void shows(){
        changHong.show();
        bingPo.show();
        ziYun.show();
        System.out.println("三剑合璧");
    }}

Test

new a three-sword combination object, call the three-sword combination method

public class Demo {
    public static void main(String[] args) {
        San san=new San();
        san.shows();
    }}

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