Android Java如何实现跨Activity的应用内持久通知？

问题根源 #

当前应用内通知绑定在单个Activity的View层级中，切换Activity时原Activity进入onPause/onStop状态，通知View被销毁，导致通知提前消失。要实现跨Activity持续显示，核心是让通知的生命周期不依赖单个Activity。

方案一：全局悬浮窗（Overlay）实现 #

这是最贴合Instagram/Twitter体验的方案，通知属于系统窗口层级，不依附任何Activity，切换页面完全无感知。

实现步骤 #

1. 申请权限
   在AndroidManifest.xml中声明权限：

   <uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW" />
   

   Android 6.0+需动态引导用户开启权限：

   if (!Settings.canDrawOverlays(this)) {
       Intent intent = new Intent(Settings.ACTION_MANAGE_OVERLAY_PERMISSION,
               Uri.parse("package:" + getPackageName()));
       startActivityForResult(intent, 1001);
   }
   

2. 全局通知管理单例
   创建单例类统一处理通知的显示、隐藏和计时逻辑：

   public class InAppNotificationManager {
       private static InAppNotificationManager instance;
       private WindowManager windowManager;
       private View notificationView;
       private Handler handler = new Handler(Looper.getMainLooper());
       private Runnable hideRunnable;
   
       private InAppNotificationManager(Context context) {
           windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
       }
   
       public static synchronized InAppNotificationManager getInstance(Context context) {
           if (instance == null) {
               instance = new InAppNotificationManager(context.getApplicationContext());
           }
           return instance;
       }
   
       public void showNotification(String content, long duration) {
           // 移除已有通知
           hideNotification();
   
           // 加载自定义通知布局
           notificationView = LayoutInflater.from(windowManager.getContext())
                   .inflate(R.layout.in_app_notification, null);
           TextView contentTv = notificationView.findViewById(R.id.tv_content);
           contentTv.setText(content);
   
           // 配置窗口参数
           WindowManager.LayoutParams params = new WindowManager.LayoutParams();
           if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
               params.type = WindowManager.LayoutParams.TYPE_APPLICATION_OVERLAY;
           } else {
               params.type = WindowManager.LayoutParams.TYPE_PHONE;
           }
           params.format = PixelFormat.TRANSLUCENT;
           params.flags = WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE
                   | WindowManager.LayoutParams.FLAG_LAYOUT_IN_SCREEN
                   | WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS;
           params.width = WindowManager.LayoutParams.MATCH_PARENT;
           params.height = WindowManager.LayoutParams.WRAP_CONTENT;
           params.gravity = Gravity.TOP;
   
           // 添加到系统窗口
           windowManager.addView(notificationView, params);
   
           // 计时自动隐藏
           hideRunnable = this::hideNotification;
           handler.postDelayed(hideRunnable, duration);
       }
   
       public void hideNotification() {
           if (notificationView != null && windowManager != null) {
               handler.removeCallbacks(hideRunnable);
               windowManager.removeView(notificationView);
               notificationView = null;
           }
       }
   }
   

3. 调用方式
   在任意Activity或组件中直接调用：

   InAppNotificationManager.getInstance(this).showNotification("您有一条新消息", 3000);
   

方案二：BaseActivity统一管理+状态保存 #

若不想申请悬浮窗权限，可通过BaseActivity统一处理通知的重建，兼容性更好，仅存在切换页面时短暂的重绘过程。

实现步骤 #

1. 通知状态管理单例
   保存通知的内容、剩余时长和激活状态：

   public class NotificationStateManager {
       private static NotificationStateManager instance;
       private String currentContent;
       private long startTime;
       private long totalDuration;
       private boolean isActive;
   
       private NotificationStateManager() {}
   
       public static synchronized NotificationStateManager getInstance() {
           if (instance == null) {
               instance = new NotificationStateManager();
           }
           return instance;
       }
   
       public void activateNotification(String content, long duration) {
           currentContent = content;
           totalDuration = duration;
           startTime = System.currentTimeMillis();
           isActive = true;
       }
   
       public void deactivateNotification() {
           isActive = false;
           currentContent = null;
       }
   
       public boolean hasActiveNotification() {
           return isActive && (System.currentTimeMillis() - startTime) < totalDuration;
       }
   
       public String getContent() {
           return currentContent;
       }
   
       public long getRemainingDuration() {
           if (!hasActiveNotification()) return 0;
           return totalDuration - (System.currentTimeMillis() - startTime);
       }
   }
   

2. BaseActivity统一处理
   所有业务Activity继承该BaseActivity，在onResume时检查并重建通知：

   public abstract class BaseActivity extends AppCompatActivity {
       private View notificationView;
       private Handler handler = new Handler(Looper.getMainLooper());
       private Runnable hideRunnable;
   
       @Override
       protected void onResume() {
           super.onResume();
           checkAndRestoreNotification();
       }
   
       @Override
       protected void onPause() {
           super.onPause();
           removeNotificationView();
       }
   
       private void checkAndRestoreNotification() {
           NotificationStateManager stateManager = NotificationStateManager.getInstance();
           if (stateManager.hasActiveNotification()) {
               showNotification(stateManager.getContent(), stateManager.getRemainingDuration());
           }
       }
   
       private void showNotification(String content, long remainingDuration) {
           removeNotificationView();
   
           // 加载通知布局并添加到当前Activity根布局
           notificationView = LayoutInflater.from(this)
                   .inflate(R.layout.in_app_notification, findViewById(android.R.id.content), false);
           TextView contentTv = notificationView.findViewById(R.id.tv_content);
           contentTv.setText(content);
           findViewById(android.R.id.content).addView(notificationView);
   
           // 计时隐藏并更新状态
           hideRunnable = () -> {
               removeNotificationView();
               NotificationStateManager.getInstance().deactivateNotification();
           };
           handler.postDelayed(hideRunnable, remainingDuration);
       }
   
       private void removeNotificationView() {
           if (notificationView != null) {
               handler.removeCallbacks(hideRunnable);
               ((ViewGroup) notificationView.getParent()).removeView(notificationView);
               notificationView = null;
           }
       }
   }
   

3. 调用方式
   在任意Activity中触发通知：

   NotificationStateManager.getInstance().activateNotification("新通知提醒", 3000);
   

方案对比 #

内容的提问来源于stack exchange，提问作者KZMKBL