实现Android动态列表新项目通知的教程

// 用户尝试的通知逻辑片段
for(int i = result.items.data.size(); i <= result.items.data.size(); i++) {
    // ...
    if(i > result.items.data.size()){ // 此条件永远为假
        // 通知创建和发送代码
    }else if(i == result.items.data.size()){ // 此条件仅在循环的唯一一次迭代中为真
        MotionToast.Companion.darkColorToast(...);
    }
}

// 在 EventsActivity 中定义 SharedPreferences 的键
private static final String PREFS_NAME = "event_prefs";
private static final String KEY_LAST_KNOWN_EVENT_ID = "last_known_event_id";

// 保存最新事件ID的方法
private void saveLastKnownEventId(int eventId) {
    SharedPreferences prefs = getSharedPreferences(PREFS_NAME, MODE_PRIVATE);
    prefs.edit().putInt(KEY_LAST_KNOWN_EVENT_ID, eventId).apply();
}

// 获取上次已知最新事件ID的方法
private int getLastKnownEventId() {
    SharedPreferences prefs = getSharedPreferences(PREFS_NAME, MODE_PRIVATE);
    return prefs.getInt(KEY_LAST_KNOWN_EVENT_ID, 0); // 初始值为0，表示从未有事件
}

import android.app.NotificationChannel;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Build;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.NotificationCompat;
import java.util.ArrayList;
import java.util.Random;

public class EventsActivity extends AppCompatActivity {
    // ... (现有成员变量和ButterKnife绑定) ...

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

        final String api_key = (String) DataSaver.getInstance(EventsActivity.this).load("api_key");
        final EventsAdapter adapter = new EventsAdapter(this);
        list.setAdapter(adapter);

        loading_layout.setVisibility(View.VISIBLE);
        fetchEvents(api_key, adapter);
    }

    private void fetchEvents(String apiKey, final EventsAdapter adapter) {
        API.getApiInterface(this).getEvents(apiKey, getResources().getString(R.string.lang), 0, new Callback<ApiInterface.GetEventsResult>() {
            @Override
            public void success(ApiInterface.GetEventsResult result, Response response) {
                loading_layout.setVisibility(View.GONE);
                ArrayList<Event> newEventsData = result.items.data;

                if (newEventsData != null && !newEventsData.isEmpty()) {
                    content_layout.setVisibility(View.VISIBLE);
                    adapter.setArray(newEventsData); // 更新ListView

                    // 获取当前最新事件ID
                    int currentLatestEventId = newEventsData.get(0).id;
                    // 获取上次已知最新事件ID
                    int lastKnownEventId = getLastKnownEventId();

                    // 比较ID，判断是否有新事件
                    if (currentLatestEventId > lastKnownEventId) {
                        // 发现新事件，发送通知
                        sendNewEventNotification(newEventsData.get(0));
                        // 更新上次已知最新事件ID
                        saveLastKnownEventId(currentLatestEventId);
                    } else if (lastKnownEventId == 0 && currentLatestEventId > 0) {
                        // 首次加载数据时，不发送通知，但保存最新ID
                        saveLastKnownEventId(currentLatestEventId);
                    }

                } else {
                    nodata_layout.setVisibility(View.VISIBLE);
                }
            }

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

    // ... (SharedPreferences 辅助方法，如上述 3.1 所示) ...

    // 发送新事件通知的方法
    private void sendNewEventNotification(Event newEvent) {
        String channelId = "event_notification_channel";
        String channelName = "新事件通知";
        NotificationManager notificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);

        // 创建通知渠道 (Android O 及以上版本需要)
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            if (notificationManager != null && notificationManager.getNotificationChannel(channelId) == null) {
                NotificationChannel channel = new NotificationChannel(
                        channelId,
                        channelName,
                        NotificationManager.IMPORTANCE_HIGH
                );
                channel.setDescription("用于通知用户有新的事件发生");
                channel.enableLights(true);
                channel.enableVibration(true);
                notificationManager.createNotificationChannel(channel);
            }
        }

        // 构建点击通知后的 Intent
        Intent intent = new Intent(this, EventsActivity.class); // 点击通知回到 EventsActivity
        intent.putExtra("event_id", newEvent.id); // 可以传递事件ID，以便在Activity中处理
        intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_SINGLE_TOP); // 避免重复创建Activity

        @SuppressLint("UnspecifiedImmutableFlag")
        PendingIntent pendingIntent = PendingIntent.getActivity(
                this,
                newEvent.id, // 使用事件ID作为请求码，确保每个新事件有唯一的PendingIntent
                intent,
                PendingIntent.FLAG_UPDATE_CURRENT | (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M ? PendingIntent.FLAG_IMMUTABLE : 0)
        );

        // 构建通知
        NotificationCompat.Builder builder = new NotificationCompat.Builder(this, channelId)
                .setSmallIcon(R.drawable.ic_notification_original) // 替换为你的通知图标
                .setContentTitle("新事件提醒")
                .setContentText("设备 " + newEvent.device_name + " 有新事件：" + newEvent.message)
                .setPriority(NotificationCompat.PRIORITY_HIGH)
                .setContentIntent(pendingIntent)
                .setAutoCancel(true) // 用户点击后自动取消通知
                .setDefaults(NotificationCompat.DEFAULT_ALL); // 默认铃声、震动、指示灯

        // 发送通知
        if (notificationManager != null) {
            // 使用事件ID作为通知ID，确保每个新事件的通知是唯一的，或者覆盖旧的同类通知
            notificationManager.notify(newEvent.id, builder.build());
        }
    }
}