如何将项目添加到具有Android Room中父实体的外键引用的子实体（）

博观而约取，厚积而薄发。这篇文章主要讲述如何将项目添加到具有Android Room中父实体的外键引用的子实体？相关的知识，希望能为你提供帮助。
我正在尝试编写一个类似于Strava的简单应用程序，它将使用Room Persistence Library记录活动
我的两个实体是：

@Entity public class ActivityRecord { @PrimaryKey(autoGenerate = true) private long id; private Date startTimestamp; private Date endTimestamp; public ActivityRecord() { this.startTimestamp = new Date(); this.endTimestamp = this.startTimestamp; }public long getId() { return id; }public void setId(long id) { this.id = id; }public Date getStartTimestamp() { return startTimestamp; }public void setStartTimestamp(Date startTimestamp) { this.startTimestamp = startTimestamp; }public Date getEndTimestamp() { return endTimestamp; }public void setEndTimestamp(Date endTimestamp) { this.endTimestamp = endTimestamp; } }

和：

@Entity(foreignKeys = @ForeignKey( entity = ActivityRecord.class, parentColumns = "id", childColumns = "recordId", onDelete = CASCADE), indices = {@Index(value = https://www.songbingjia.com/android/{"recordId"})}) public class ActivityLocation {@PrimaryKey(autoGenerate = true) private long id; private double latitude; private double longitude; private long recordId; public ActivityLocation(double latitude, double longitude, long recordId) { this.latitude = latitude; this.longitude = longitude; this.recordId = recordId; }public long getId() { return id; }public void setId(long id) { this.id = id; }public double getLatitude() { return latitude; }public void setLatitude(double latitude) { this.latitude = latitude; }public double getLongitude() { return longitude; }public void setLongitude(double longitude) { this.longitude = longitude; }public long getRecordId() { return recordId; }public void setRecordId(long recordId) { this.recordId = recordId; } }

我还创建了这两个DAO：

@Dao public interface ActivityRecordDao { @Query("SELECT * FROM ActivityRecord ORDER BY id DESC") LiveData< List< ActivityRecord> > getActivityRecords(); @Query("SELECT * FROM ActivityRecord WHERE id = :id") ActivityRecord getActivityRecordById(long id); @Query("SELECT * FROM ActivityRecord ORDER BY id DESC LIMIT 1") ActivityRecord getLastActivityRecord(); @Insert long setActivityRecord(ActivityRecord record); @Update void updateActivityRecord(ActivityRecord record); @Delete void deleteActivityRecord(ActivityRecord record); }

和：

@Dao public interface ActivityLocationDao { @Query("SELECT * FROM ActivityLocation ORDER BY timestamp DESC") LiveData< List< ActivityLocation> > getActivityLocations(); @Query("SELECT * FROM ActivityLocation WHERE id = :id") ActivityLocation getActivityLocationById(long id); @Query("SELECT * FROM ActivityLocation WHERE recordId = :recordId") LiveData< List< ActivityLocation> > getActivityLocationsByRecordId(long recordId); @Insert void setActivityLocation(ActivityLocation location); @Delete void deleteActivityLocation(ActivityLocation location); }

我可以从ActivityRecords插入，更新和删除MainActivity.java，但我还没有发现当我从ActivityLocation收到更新的位置数据时，如何在我的BroadcastReceiver中插入带有外键引用的新com.google.android.gms.location.LocationResult
所以，我的问题是，如何添加一个ActivityLocation子项目参考ActivityRecord父项目，如何在我的BroadcastReceiver中获取我的应用程序数据库的实例？
答案解决了我的BroadcastReceiver中的AsyncTask问题。
【如何将项目添加到具有Android Room中父实体的外键引用的子实体（）】我首先需要将activityLocations的上下文和列表作为参数传递。通过创建私有params类解决了这个问题：

private static class ActivityLocationParams { Context context; List< ActivityLocation> locations; ActivityLocationParams(Context context, List< ActivityLocation> locations) { this.context = context; this.locations = locations; } }

接下来我创建了一个私有的AsyncTask类：

private static class addActivityLocationAsyncTask extends AsyncTask< ActivityLocationParams, Void, Integer> { @Override protected Integer doInBackground(ActivityLocationParams... params) { Context context = params[0].context; List< ActivityLocation> locations = params[0].locations; AppDatabase db = AppDatabase.getInstance(context); ActivityRecord activityRecord = db.activityRecordDao().getLastActivityRecord(); int count = 0; for (ActivityLocation location : locations) { if (activityRecord == null) { continue; }ActivityLocation activityLocation = new ActivityLocation(location.getLatitude(), location.getLongitude(), activityRecord.getId()); db.activityLocationDao().setActivityLocation(activityLocation); count += 1; }return count; }@Override protected void onPostExecute(Integer count) { Log.d(TAG, "Number of ActivityLocations added: " + count.toString()); } }

在完成doInBackground之后，我打印出添加到数据库中的项目数，以便进行调试。
最后我创建了params对象并在BroadcastReceiver中调用了AsyncTask：