如何不使用Geofire在Firebase中保存Location对象？

我来帮你搞定这个问题！确实，Android的Location对象包含很多有用的元数据（比如精度、海拔、速度等），只存坐标太浪费这些信息了。下面是两种靠谱的实现方式，既能完整保存，又能方便后续检索：

方法一：用HashMap手动封装Location属性 #

Firebase Realtime Database支持存储HashMap类型的数据，我们可以把Location的所有关键属性提取出来存入HashMap，再写入Firebase：

// 假设你已经获取到了Android的Location对象
Location userLocation = ...;

// 创建HashMap来存储Location的所有属性
HashMap<String, Object> locationMap = new HashMap<>();
locationMap.put("latitude", userLocation.getLatitude());
locationMap.put("longitude", userLocation.getLongitude());
locationMap.put("accuracy", userLocation.getAccuracy());
locationMap.put("altitude", userLocation.getAltitude());
locationMap.put("bearing", userLocation.getBearing());
locationMap.put("speed", userLocation.getSpeed());
locationMap.put("time", userLocation.getTime());
locationMap.put("provider", userLocation.getProvider());

// 写入Firebase Realtime Database
DatabaseReference dbRef = FirebaseDatabase.getInstance().getReference("user_locations").child("user_123");
dbRef.setValue(locationMap)
    .addOnSuccessListener(aVoid -> {
        // 保存成功的逻辑
    })
    .addOnFailureListener(e -> {
        // 处理错误
    });

检索时的还原操作：

dbRef.addValueEventListener(new ValueEventListener() {
    @Override
    public void onDataChange(@NonNull DataSnapshot snapshot) {
        if (snapshot.exists()) {
            HashMap<String, Object> locationMap = (HashMap<String, Object>) snapshot.getValue();
            
            // 还原成Android Location对象
            Location restoredLocation = new Location((String) locationMap.get("provider"));
            restoredLocation.setLatitude((Double) locationMap.get("latitude"));
            restoredLocation.setLongitude((Double) locationMap.get("longitude"));
            restoredLocation.setAccuracy((Float) locationMap.get("accuracy"));
            restoredLocation.setAltitude((Double) locationMap.get("altitude"));
            restoredLocation.setBearing((Float) locationMap.get("bearing"));
            restoredLocation.setSpeed((Float) locationMap.get("speed"));
            restoredLocation.setTime((Long) locationMap.get("time"));
            
            // 现在你就可以使用完整的Location对象了
        }
    }

    @Override
    public void onCancelled(@NonNull DatabaseError error) {
        // 处理取消事件
    }
});

方法二：自定义LocationModel类（更规范的方式） #

如果不想每次都手动封装HashMap，建议创建一个自定义的LocationModel类，把Location的属性作为类字段，Firebase会自动序列化/反序列化这个对象：

import com.google.firebase.database.IgnoreExtraProperties;

@IgnoreExtraProperties // 忽略Firebase中不存在的字段
public class LocationModel {
    public double latitude;
    public double longitude;
    public float accuracy;
    public double altitude;
    public float bearing;
    public float speed;
    public long time;
    public String provider;

    // 必须要有一个无参构造方法，Firebase序列化需要
    public LocationModel() {}

    // 从Android Location对象构造LocationModel
    public LocationModel(Location location) {
        this.latitude = location.getLatitude();
        this.longitude = location.getLongitude();
        this.accuracy = location.getAccuracy();
        this.altitude = location.getAltitude();
        this.bearing = location.getBearing();
        this.speed = location.getSpeed();
        this.time = location.getTime();
        this.provider = location.getProvider();
    }

    // 还原成Android Location对象的方法
    public Location toAndroidLocation() {
        Location location = new Location(this.provider);
        location.setLatitude(this.latitude);
        location.setLongitude(this.longitude);
        location.setAccuracy(this.accuracy);
        location.setAltitude(this.altitude);
        location.setBearing(this.bearing);
        location.setSpeed(this.speed);
        location.setTime(this.time);
        return location;
    }
}

保存到Firebase的代码：

Location userLocation = ...;
LocationModel locationModel = new LocationModel(userLocation);

DatabaseReference dbRef = FirebaseDatabase.getInstance().getReference("user_locations").child("user_123");
dbRef.setValue(locationModel)
    .addOnSuccessListener(aVoid -> {
        // 保存成功
    })
    .addOnFailureListener(e -> {
        // 处理错误
    });

检索时的还原：

dbRef.addValueEventListener(new ValueEventListener() {
    @Override
    public void onDataChange(@NonNull DataSnapshot snapshot) {
        if (snapshot.exists()) {
            LocationModel locationModel = snapshot.getValue(LocationModel.class);
            if (locationModel != null) {
                Location restoredLocation = locationModel.toAndroidLocation();
                // 使用还原后的Location对象
            }
        }
    }

    @Override
    public void onCancelled(@NonNull DatabaseError error) {
        // 处理取消事件
    }
});

注意事项 #

• 有些Location属性可能为空（比如如果设备没有海拔传感器，altitude可能是0或者无效值），保存前可以做一下空值判断，避免存入无效数据。
• 如果使用Firebase Firestore而不是Realtime Database，逻辑是类似的，只是API略有不同，同样可以用HashMap或者自定义类来处理。

内容的提问来源于stack exchange，提问作者Ashu.mkb