Bridge Pattern

motivation

Applicable scenarios

• You don't want a fixed binding between the abstraction and its implementation. For example, this is because the implementation part can be selected or switched when the program is running.

• Class abstraction and its implementation can be extended by generating subclasses. The bridge pattern allows you to combine and extend different abstract interfaces and implementation parts.

• Changes to an abstract implementation do not affect the customer.

• Multiple objects share the implementation, but at the same time the customer is not aware of this.

structure

Code example

//Abstract class, TV related operation
public abstract class RemoteCotrol {

    private TV tv;

    public RemoteCotrol(TV tv) {
        this.tv = tv;
    }

    public TV getTv() {
        return tv;
    }

    public abstract void on();
    public abstract void off();
    public abstract void setChannel();
}

//tv interface 
public interface TV {

    void on();

    void off();

    void tuneChannel();
}

//tv interface implementation class to realize the operation related to tv series
public class RCA implements TV {

    @Override
    public void on() {
        System.out.println("rca on");
    }

    @Override
    public void off() {
        System.out.println("rca off");
    }

    @Override
    public void tuneChannel() {
        System.out.println("rca CCTV");
    }
}

//tv interface implementation class to realize the operation related to tv series
public class Sony implements TV {
    @Override
    public void on() {
        System.out.println("sony on");
    }

    @Override
    public void off() {
        System.out.println("sony off");
    }

    @Override
    public void tuneChannel() {
        System.out.println("sony cctv");
    }
}

//Abstract implementation class, association interface, use interface to implement Abstract TV series related operations
public class ConsreteRemode extends RemoteCotrol {

    public ConsreteRemode(TV tv) {
        super(tv);
    }

    @Override
    public void on() {
        getTv().on();
    }

    @Override
    public void off() {
        getTv().off();
    }

    @Override
    public void setChannel() {
        getTv().tuneChannel();
    }
}

public class Client{
  public static void main(String[] args) {
        RemoteCotrol sony = new ConsreteRemode(new Sony());
        sony.on();

        RemoteCotrol rca = new ConsreteRemode(new RCA());
        rca.on();
    }
}

: sony on : rca on

summary

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