有什么办法可以让 Snackbar 在活动变化中保持不变？

要使用跨多个活动可见的应用程序上下文创建 Snackbar：

1. 获取WindowManager作为系统服务
2. 创建一个WindowManager.LayoutParams.TYPE_TOAST和WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL类型的FrameLayout ( rootView ) 并添加到WindowManager
3. 等到FrameLayout.onAttachedToWindow()在FrameLayout ( rootView ) 中被调用
4. 使用View.getWindowToken()获取FrameLayout ( rootView ) 的窗口令牌
5. 创建ContextThemeWrapper与应用程序上下文和派生@style/Theme.AppCompat
6. 使用新的上下文创建一个额外的FrameLayout （ snackbarContainer ）
7. 添加类型为WindowManager.LayoutParams.TYPE_APPLICATION_PANEL和标志WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL FrameLayout （ snackbarContainer ）
8. 等到View.onAttachedToWindow()在FrameLayout被调用（ snackbarContainer ）
9. 使用FrameLayout像往常一样创建 Snackbar（ snackbarContainer ）
10. 将View.onDismissed()回调设置为 Snackbar 并删除 FrameLayouts（ rootView和snapbarContainer ）
11. 显示小吃店Snackbar.show()

这里有一个工作包装器（ 注意：滑动关闭不起作用。也许其他人找到了正确的 WindowManager.LayoutParams标志来接收 由 CoordinatorLayout 修复的 触摸事件 ）：

public class SnackbarWrapper
{
    private final CharSequence text;
    private final int duration;
    private final WindowManager windowManager;
    private final Context appplicationContext;
    @Nullable
    private Snackbar.Callback externalCallback;
    @Nullable
    private Action action;

    @NonNull
    public static SnackbarWrapper make(@NonNull Context applicationContext, @NonNull CharSequence text, @Snackbar.Duration int duration)
    {
        return new SnackbarWrapper(applicationContext, text, duration);
    }

    private SnackbarWrapper(@NonNull final Context appplicationContext, @NonNull CharSequence text, @Snackbar.Duration int duration)
    {
        this.appplicationContext = appplicationContext;
        this.windowManager = (WindowManager) appplicationContext.getSystemService(Context.WINDOW_SERVICE);
        this.text = text;
        this.duration = duration;
    }

    public void show()
    {
        WindowManager.LayoutParams layoutParams = createDefaultLayoutParams(WindowManager.LayoutParams.TYPE_TOAST, null);
        windowManager.addView(new FrameLayout(appplicationContext)
        {
            @Override
            protected void onAttachedToWindow()
            {
                super.onAttachedToWindow();
                onRootViewAvailable(this);
            }

        }, layoutParams);
    }

    private void onRootViewAvailable(final FrameLayout rootView)
    {
        final CoordinatorLayout snackbarContainer = new CoordinatorLayout(new ContextThemeWrapper(appplicationContext, R.style.FOL_Theme_SnackbarWrapper))
        {
            @Override
            public void onAttachedToWindow()
            {
                super.onAttachedToWindow();
                onSnackbarContainerAttached(rootView, this);
            }
        };
        windowManager.addView(snackbarContainer, createDefaultLayoutParams(WindowManager.LayoutParams.TYPE_APPLICATION_PANEL, rootView.getWindowToken()));
    }

    private void onSnackbarContainerAttached(final View rootView, final CoordinatorLayout snackbarContainer)
    {
        Snackbar snackbar = Snackbar.make(snackbarContainer, text, duration);
        snackbar.setCallback(new Snackbar.Callback()
        {
            @Override
            public void onDismissed(Snackbar snackbar, int event)
            {
                super.onDismissed(snackbar, event);
                // Clean up (NOTE! This callback can be called multiple times)
                if (snackbarContainer.getParent() != null && rootView.getParent() != null)
                {
                    windowManager.removeView(snackbarContainer);
                    windowManager.removeView(rootView);
                }
                if (externalCallback != null)
                {
                    externalCallback.onDismissed(snackbar, event);
                }
            }

            @Override
            public void onShown(Snackbar snackbar)
            {
                super.onShown(snackbar);
                if (externalCallback != null)
                {
                    externalCallback.onShown(snackbar);
                }
            }
        });
        if (action != null)
        {
            snackbar.setAction(action.text, action.listener);
        }
        snackbar.show();
    }

    private WindowManager.LayoutParams createDefaultLayoutParams(int type, @Nullable IBinder windowToken)
    {
        WindowManager.LayoutParams layoutParams = new WindowManager.LayoutParams();
        layoutParams.format = PixelFormat.TRANSLUCENT;
        layoutParams.width = WindowManager.LayoutParams.MATCH_PARENT;
        layoutParams.height = WindowManager.LayoutParams.WRAP_CONTENT;
        layoutParams.gravity = GravityCompat.getAbsoluteGravity(Gravity.CENTER_HORIZONTAL | Gravity.BOTTOM, ViewCompat.LAYOUT_DIRECTION_LTR);
        layoutParams.flags = WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL;
        layoutParams.type = type;
        layoutParams.token = windowToken;
        return layoutParams;
    }

    @NonNull
    public SnackbarWrapper setCallback(@Nullable Snackbar.Callback callback)
    {
        this.externalCallback = callback;
        return this;
    }

    @NonNull
    public SnackbarWrapper setAction(CharSequence text, final View.OnClickListener listener)
    {
        action = new Action(text, listener);
        return this;
    }

    private static class Action
    {
        private final CharSequence text;
        private final View.OnClickListener listener;

        public Action(CharSequence text, View.OnClickListener listener)
        {
            this.text = text;
            this.listener = listener;
        }
    }
}

编辑
定义SnackbarWrapper ，您可以像这样使用它：

final SnackbarWrapper snackbarWrapper = SnackbarWrapper.make(getApplicationContext(),
            "Test snackbarWrapper", Snackbar.LENGTH_LONG);

snackbarWrapper.setAction(R.string.snackbar_text,
            new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    Toast.makeText(getApplicationContext(), "Action",
                            Toast.LENGTH_SHORT).show();
                }
            });

snackbarWrapper.show();

如果你没有主题，你可以在styles.xml快速定义一个：

<style name="FOL_Theme_SnackbarWrapper" parent="@style/Theme.AppCompat">
    <!--Insert customization here-->
</style>

编辑
对于 Android Oreo 上出现 Bad Token Exception 的用户，请将 TYPE_TOAST 更改为 TYPE_APPLICATION_OVERLAY。 这是由于 Android Oreo 实施了特殊权限来绘制应用程序。 您可以使用以下方法请求此权限：

    if(!Settings.canDrawOverlays(Activity.this){
        Intent intent = new Intent(Settings.ACTION_MANAGE_OVERLAY_PERMISSION, URI.parse("package:" + getPackageName()));
        startActivityForResult(intent, REQ_CODE);
    }