java - 在 fragment 之间共享进度

Question

我有几个 fragment 。其中之一可以启动IntentService进行繁重的操作。问题是，从另一个 fragment 获取后台任务的进度/状态的最佳方法是什么？

Answer 1

如果你想要类似回调机制，你可以为其实现类似观察者的架构/模式。

了解Observer pattern on wikipedia (带有 Java 示例)

这是我给您的示例:

public class ObservableProgress {

    public interface Observer {
        void onProgressChanged(Object newProgress);
    }

    // I do not know the type of your progress
    private static volatile Object progress;

    private static final List<Observer> observers = new LinkedList<Observer>();

    // closing constructor for clear class's api
    private ObservableProgress() {}

    // on each progress change, all observers would be notified about progress change
    public static void setProgress(Object newProgress) {
        progress = newProgress;
        notifyOnProgressChanged(newProgress);
    }

    public static Object getProgress() {
        return progress;
    }

    // use it to add progress listener
    public static void addObserver(Observer observer) {
        observers.add(observer);
    }

    // use it to remove progress listener
    public static void removeObserver(Observer observer) {
        observers.remove(observer);
    }

    private static void notifyOnProgressChanged(Object newProgress) {
        for (Observer observer : observers) {
            if (observer != null) {
                observer.onProgressChanged(newProgress);
            }
        }
    }

}