JavaFx可观察实体无需更改实体本身

Question

我有一个实体类，它有很多字段，我想为这个类创建可观察的实体，这样我就可以使用它来绑定(bind)。

实体的代码无法更改。我该怎么做？

假设我的代码如下所示:

class Car {

   private Wheel wheel;
   private Engine engine;
   private Door door;

   // and a lot of field.

}

并且我想创建 ObservableCar ，每次任何字段更改时它都会变得无效。

The car code doesn't change. And the class of the field too.

我该怎么做？

提前致谢。

Answer 1

实现您的Car使用 JavaFX 属性的类:

public class Car {

    private final ObjectProperty<Wheel> wheel = new SimpleObjectProperty<>();
    public ObjectProperty<Wheel> wheelProperty() {
        return wheel ;
    }
    public final Wheel getWheel() {
        return wheelProperty().get();
    }
    public final void setWhee(Wheel wheel) {
        wheelProperty.set(wheel);
    }

    // other properties...

}

现在您可以创建 ObjectBinding<Car>当任何属性无效时，该属性也会无效:

public class CarBinding extends ObjectBinding<Car> {

    private final Car car ;

    public CarBinding(Car car) {
        this.car = car ;
        bind(car.wheelProperty(), car.engineProperty(), ...);
    }

    @Override
    public Car computeValue() {
        return car ;
    }
}

如果更方便，您可以将绑定(bind)直接构建到您的汽车类中:

public class Car {

    // properties as before...

    private final ObjectBinding<Car> carBinding = new ObjectBinding<Car>() {
        {
            bind(wheelProperty(), engineProperty(), ...);
        }

        @Override
        public Car computeValue() {
            return Car.this ;
        }
    }

    public ObjectBinding<Car> asBinding() {
        return carBinding ;
    }
}