android懸浮窗的兩種實現方案

第一種實現，不依賴於activity，使用系統級別的WindowManager來添加view：

<!- 添加權限 -> 
<uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW" />
<uses-permission android:name="android.permission.SYSTEM_OVERLAY_WINDOW" />

// 安卓8.0以上需要申請權限
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O && !Settings.canDrawOverlays(BaseApplication.getInstance())){
   Intent intent = new Intent(Settings.ACTION_MANAGE_OVERLAY_PERMISSION);
   startActivity(intent);
   return;
}

WindowManager windowManager = (WindowManager) BaseApplication.getInstance().getSystemService(Context.WINDOW_SERVICE);
WindowManager.LayoutParams layoutParams = new WindowManager.LayoutParams();
// 設置寬高
layoutParams.width = WindowManager.LayoutParams.MATCH_PARENT;
layoutParams.height = WindowManager.LayoutParams.WRAP_CONTENT;
// 設置背景透明
layoutParams.format = PixelFormat.TRANSPARENT;
// 設置屏幕左上角爲起始點
layoutParams.gravity = Gravity.LEFT | Gravity.TOP;
// FLAG_LAYOUT_IN_SCREEN：將window放置在整個屏幕之內,無視其他的裝飾(比如狀態欄)； FLAG_NOT_TOUCH_MODAL：不阻塞事件傳遞到後面的窗口
layoutParams.flags = WindowManager.LayoutParams.FLAG_LAYOUT_IN_SCREEN | WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL | WindowManager.LayoutParams.FLAG_WATCH_OUTSIDE_TOUCH;
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
    layoutParams.type = WindowManager.LayoutParams.TYPE_APPLICATION_OVERLAY;
} else {
    // 設置窗體顯示類型(TYPE_TOAST:與toast一個級別)
    layoutParams.type = WindowManager.LayoutParams.TYPE_TOAST;
}
// 設置佈局彈出的動畫
layoutParams.windowAnimations = R.style.anim;
// 添加視圖
View contentView = LayoutInflater.from(BaseApplication.getInstance()).inflate(R.layout.content_view, null);
windowManager.addView(contentView, layoutParams);

 

 

第二種實現，在應用內實現懸浮窗，需要依賴activity，可通過反射機制獲取當前頂部窗口：

/**
 * 獲取頂部activity
 * @return
 */
private Activity getTopActivity() {
    try {
        Class activityThreadClass = Class.forName("android.app.ActivityThread");
        Object activityThread = activityThreadClass.getMethod("currentActivityThread").invoke(null);
        Field activitiesField = activityThreadClass.getDeclaredField("mActivities");
        activitiesField.setAccessible(true);
        Map activities = (Map) activitiesField.get(activityThread);
        for (Object activityRecord : activities.values()) {
            Class activityRecordClass = activityRecord.getClass();
            Field pausedField = activityRecordClass.getDeclaredField("paused");
            pausedField.setAccessible(true);
            if (!pausedField.getBoolean(activityRecord)) {
                Field activityField = activityRecordClass.getDeclaredField("activity");
                activityField.setAccessible(true);
                Activity activity = (Activity) activityField.get(activityRecord);
                return activity;
            }
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
    return null;
}

// 在頂部窗口上面添加懸浮窗
Activity activity = getTopActivity();
View rootView = activity.getWindow().getDecorView().getRootView();
ViewGroup contentView = rootView.findViewById(android.R.id.content);
View floatView = LayoutInflater.from(BaseApplication.getInstance()).inflate(R.layout.float_view, null);
// 添加視圖
contentView.addView(floatView);
// 添加動畫
floatView.startAnimation(AnimationUtils.loadAnimation(floatView.getContext(), R.anim.anim));