CS-Notes/notes/设计模式 - 桥接.md

## 桥接（Bridge）

### Intent

将抽象与实现分离开来，使它们可以独立变化。

### Class Diagram

- Abstraction：定义抽象类的接口
- Implementor：定义实现类接口

<div align="center"> <img src="https://cs-notes-1256109796.cos.ap-guangzhou.myqcloud.com/2a1f8b0f-1dd7-4409-b177-a381c58066ad.png"/> </div><br>

### Implementation

RemoteControl 表示遥控器，指代 Abstraction。

TV 表示电视，指代 Implementor。

桥接模式将遥控器和电视分离开来，从而可以独立改变遥控器或者电视的实现。

```java
public abstract class TV {
    public abstract void on();

    public abstract void off();

    public abstract void tuneChannel();
}
```

```java
public class Sony extends 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.tuneChannel()");
    }
}
```

```java
public class RCA extends 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.tuneChannel()");
    }
}
```

```java
public abstract class RemoteControl {
    protected TV tv;

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

    public abstract void on();

    public abstract void off();

    public abstract void tuneChannel();
}
```

```java
public class ConcreteRemoteControl1 extends RemoteControl {
    public ConcreteRemoteControl1(TV tv) {
        super(tv);
    }

    @Override
    public void on() {
        System.out.println("ConcreteRemoteControl1.on()");
        tv.on();
    }

    @Override
    public void off() {
        System.out.println("ConcreteRemoteControl1.off()");
        tv.off();
    }

    @Override
    public void tuneChannel() {
        System.out.println("ConcreteRemoteControl1.tuneChannel()");
        tv.tuneChannel();
    }
}
```

```java
public class ConcreteRemoteControl2 extends RemoteControl {
    public ConcreteRemoteControl2(TV tv) {
        super(tv);
    }

    @Override
    public void on() {
        System.out.println("ConcreteRemoteControl2.on()");
        tv.on();
    }

    @Override
    public void off() {
        System.out.println("ConcreteRemoteControl2.off()");
        tv.off();
    }

    @Override
    public void tuneChannel() {
        System.out.println("ConcreteRemoteControl2.tuneChannel()");
        tv.tuneChannel();
    }
}
```

```java
public class Client {
    public static void main(String[] args) {
        RemoteControl remoteControl1 = new ConcreteRemoteControl1(new RCA());
        remoteControl1.on();
        remoteControl1.off();
        remoteControl1.tuneChannel();
        RemoteControl remoteControl2 = new ConcreteRemoteControl2(new Sony());
         remoteControl2.on();
         remoteControl2.off();
         remoteControl2.tuneChannel();
    }
}
```

### JDK

- AWT (It provides an abstraction layer which maps onto the native OS the windowing support.)
- JDBC