Android实时数据列表新增项通知机制实现指南

import android.graphics.Color;
import android.os.Build;
import android.os.Bundle;
import android.os.Handler;
import android.os.Looper;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.NotificationCompat;
import android.app.NotificationChannel;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.view.View;
import android.widget.ListView;
import android.widget.TextView;

import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Random;
import java.util.Set;

import butterknife.Bind;
import butterknife.ButterKnife;
import retrofit.Callback;
import retrofit.RetrofitError;
import retrofit.client.Response;

public class EventsActivity extends AppCompatActivity {
    @Bind(R.id.back) View back;
    @Bind(R.id.list) ListView list;
    @Bind(R.id.clearAllEvents) View clearAllEvents;
    @Bind(R.id.content_layout) View content_layout;
    @Bind(R.id.loading_layout) View loading_layout;
    @Bind(R.id.nodata_layout) View nodata_layout;
    @Bind(R.id.search) View search;
    String searchtext;

    private EventsAdapter adapter;
    private List<Event> previousEvents = new ArrayList<>(); // 用于存储上一次获取的事件列表
    private Handler pollingHandler = new Handler(Looper.getMainLooper());
    private static final long POLLING_INTERVAL_MS = 5000; // 每5秒刷新一次数据

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_events);
        ButterKnife.bind(this);

        adapter = new EventsAdapter(this);
        list.setAdapter(adapter);

        // 首次加载数据
        fetchEvents();
    }

    @Override
    protected void onResume() {
        super.onResume();
        // 当Activity可见时开始定时刷新数据
        pollingHandler.post(fetchRunnable);
    }

    @Override
    protected void onPause() {
        super.onPause();
        // 当Activity不可见时停止定时刷新
        pollingHandler.removeCallbacks(fetchRunnable);
    }

    private Runnable fetchRunnable = new Runnable() {
        @Override
        public void run() {
            fetchEvents();
            pollingHandler.postDelayed(this, POLLING_INTERVAL_MS);
        }
    };

    private void fetchEvents() {
        final String api_key = (String) DataSaver.getInstance(EventsActivity.this).load("api_key");
        loading_layout.setVisibility(View.VISIBLE);

        API.getApiInterface(this).getEvents(api_key, getResources().getString(R.string.lang), 0, new Callback<ApiInterface.GetEventsResult>() {
            @Override
            public void success(ApiInterface.GetEventsResult result, Response response) {
                loading_layout.setVisibility(View.GONE);
                List<Event> currentEvents = result.items.data;

                if (currentEvents != null && !currentEvents.isEmpty()) {
                    // 1. 检测并发送新事件通知
                    detectAndNotifyNewEvents(currentEvents);

                    // 2. 更新UI
                    adapter.setArray(new ArrayList<>(currentEvents)); // 传递副本，避免直接修改原始数据
                    content_layout.setVisibility(View.VISIBLE);
                    nodata_layout.setVisibility(View.GONE);
                } else {
                    nodata_layout.setVisibility(View.VISIBLE);
                    content_layout.setVisibility(View.GONE);
                    adapter.setArray(new ArrayList<>()); // 清空适配器数据
                }

                // 3. 更新previousEvents为当前数据，以便下次对比
                previousEvents = new ArrayList<>(currentEvents); // 存储副本
            }

            @Override
            public void failure(RetrofitError retrofitError) {
                loading_layout.setVisibility(View.GONE);
                nodata_layout.setVisibility(View.VISIBLE);
                content_layout.setVisibility(View.GONE);
                Toast.makeText(EventsActivity.this, R.string.errorHappened, Toast.LENGTH_SHORT).show();
            }
        });
    }

    /**
     * 检测新事件并发送通知
     * @param currentEvents 当前从服务器获取的事件列表
     */
    private void detectAndNotifyNewEvents(List<Event> currentEvents) {
        // 首次加载时，不发送通知，只记录当前数据为旧数据
        if (previousEvents.isEmpty()) {
            return;
        }

        // 将旧事件的ID存入HashSet，以便高效查找
        Set<Integer> previousEventIds = new HashSet<>();
        for (Event event : previousEvents) {
            previousEventIds.add(event.id);
        }

        // 遍历当前事件列表，查找新事件
        for (Event newEvent : currentEvents) {
            if (!previousEventIds.contains(newEvent.id)) {
                // 发现新事件，发送通知
                sendNotificationForNewEvent(newEvent);
            }
        }
    }

    /**
     * 为新事件发送本地通知
     * @param event 新事件对象
     */
    private void sendNotificationForNewEvent(Event event) {
        // 生成一个随机的通知ID，确保每次通知都是独立的
        int notificationId = new Random().nextInt(100000);
        String channelId = "new_event_channel";
        String channelName = "新事件通知";

        NotificationManager notificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);

        // 为Android O (API 26) 及更高版本创建通知渠道
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            if (notificationManager != null && notificationManager.getNotificationChannel(channelId) == null) {
                NotificationChannel notificationChannel = new NotificationChannel(
                        channelId, channelName, NotificationManager.IMPORTANCE_HIGH
                );
                notificationChannel.setDescription("用于显示新事件的通知");
                notificationChannel.enableLights(true);
                notificationChannel.setLightColor(Color.RED);
                notificationChannel.enableVibration(true);
                notificationManager.createNotificationChannel(notificationChannel);
            }
        }

        // 构建点击通知后要启动的Intent
        Intent intent = new Intent(this, EventsActivity.class);
        // 可选：将事件ID传入，以便在Activity中高亮显示或定位该事件
        intent.putExtra("highlight_event_id", event.id);
        // 清除Activity栈，确保每次打开都是新的或顶部的Activity
        intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_SINGLE_TOP);

        // 创建PendingIntent，用于在通知被点击时触发
        // 对于Android 12 (API 31) 及更高版本，PendingIntent必须声明可变性
        int flags = PendingIntent.FLAG_UPDATE_CURRENT;
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) {
            flags |= PendingIntent.FLAG_IMMUTABLE;
        }
        PendingIntent pendingIntent = PendingIntent.getActivity(
                getApplicationContext(),
                notificationId, // 使用通知ID