Android 当应用程序进入后台时调用的通用方法

当应用程序进入后台时，是否有任何通用方法被调用？我不想在活动更改时执行此操作，只想在应用程序进入后台时执行此操作，即主屏幕出现。

您可以使用

ActivityLifeCycleCallbacks

实现此目的：

public class LifeCycleCallbacks implements Application.ActivityLifecycleCallbacks {

    /**
     * Keeps a count of the activities started.
     */
    private int mActivitiesStarted;
    /**
     * Keeps a count of the activities stopped.
     */
    private int mActivitiesStopped;

    @Override
    public void onActivityCreated(Activity activity, Bundle bundle) {

    }

    @Override
    public void onActivityStarted(Activity activity) {
        if (mActivitiesStarted == mActivitiesStopped) {
            // This is the session start
        }
        ++mActivitiesStarted;
    }

    @Override
    public void onActivityResumed(Activity activity) {

    }

    @Override
    public void onActivityPaused(Activity activity) {

    }

    @Override
    public void onActivityStopped(Activity activity) {
        ++mActivitiesStopped;
        if ((mActivitiesStarted > 0) && (mActivitiesStarted == mActivitiesStopped)) {
            /* This is session end. We can do things that we need to do when the app
            * session ends, i.e. send tracking info, etc. */
        }
    }

    @Override
    public void onActivitySaveInstanceState(Activity activity, Bundle bundle) {

    }

    @Override
    public void onActivityDestroyed(Activity activity) {

    }
}

最后，在

onCreate

中向

应用程序注册
LifeCycleCallbacks
类：

registerActivityLifecycleCallbacks（新生命周期Callbacks（））
您可以通过使用ActivityLifeCycleCallbacks来实现这一点：

public class LifeCycleCallbacks implements Application.ActivityLifecycleCallbacks {

    /**
     * Keeps a count of the activities started.
     */
    private int mActivitiesStarted;
    /**
     * Keeps a count of the activities stopped.
     */
    private int mActivitiesStopped;

    @Override
    public void onActivityCreated(Activity activity, Bundle bundle) {

    }

    @Override
    public void onActivityStarted(Activity activity) {
        if (mActivitiesStarted == mActivitiesStopped) {
            // This is the session start
        }
        ++mActivitiesStarted;
    }

    @Override
    public void onActivityResumed(Activity activity) {

    }

    @Override
    public void onActivityPaused(Activity activity) {

    }

    @Override
    public void onActivityStopped(Activity activity) {
        ++mActivitiesStopped;
        if ((mActivitiesStarted > 0) && (mActivitiesStarted == mActivitiesStopped)) {
            /* This is session end. We can do things that we need to do when the app
            * session ends, i.e. send tracking info, etc. */
        }
    }

    @Override
    public void onActivitySaveInstanceState(Activity activity, Bundle bundle) {

    }

    @Override
    public void onActivityDestroyed(Activity activity) {

    }
}

最后，在
onCreate
中向
应用程序注册
LifeCycleCallbacks
类：

registerActivityLifecycleCallbacks（新生命周期Callbacks（））