java - 如何在android中使用MVVM模式在在线服务器上保存数据

Question

我正在使用 MVVM 设计模式制作一个应用程序。最初我尝试在离线数据库中添加数据。现在我想将数据保存到在线服务器。

下面是我的离线数据存储代码:

NoteDao.java

@Dao
public interface NoteDao {

@Insert
void insert(Note note);

@Query("SELECT * FROM My_notes ORDER BY id DESC")
LiveData<List<Note>> getAllNotes();

} 

NotesviewModel.java

public class NotesviewModel extends AndroidViewModel {

private NoteRepository noteRepository;
private LiveData<List<Note>> allNotes;

public NotesviewModel(@NonNull Application application) {
    super(application);

    noteRepository = new NoteRepository(application);
    allNotes = noteRepository.getAllNotes();
}

public void insert(Note note){

    noteRepository.insert(note);
}

public LiveData<List<Note>> getAllNotes(){

    return allNotes;
  }
}

NoteRepository.java

public class NoteRepository {

private NoteDao noteDao;
private LiveData<List<Note>> allNotes;

public NoteRepository(Application application){

    DatabaseSingleton db = DatabaseSingleton.getInstance(application);
    noteDao = db.noteDao();
    allNotes = noteDao.getAllNotes();
}

public void insert(Note note){

    new InsertNoteAsyncTask(noteDao).execute(note);
}

public LiveData<List<Note>> getAllNotes(){

    return allNotes;
}

private static class InsertNoteAsyncTask extends AsyncTask<Note,Void,Void>{

    private NoteDao noteDao;

    private InsertNoteAsyncTask(NoteDao noteDao) {

        this.noteDao = noteDao;
    }

    @Override
    protected Void doInBackground(Note... notes) {

        noteDao.insert(notes[0]);
        return null;
     }
  }
}

AddNotes.java

 submit.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            saveNote();
        }
    });

private void saveNote(){

    String str1 = title.getText().toString();
    String str2 = description.getText().toString();

    if(str1.equals("") || str2.equals("")){

        Toast.makeText(getApplicationContext(),"Field cannot be empty",Toast.LENGTH_SHORT).show();
    }else{

        Intent i = new Intent(AddNotes.this,MainActivity.class);
        i.putExtra("title",str1);
        i.putExtra("desc",str2);
        setResult(RESULT_OK,i);
        finish();

    }
}

MainActivity.java

@Override
protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
    super.onActivityResult(requestCode, resultCode, data);

    if(requestCode == ADD_NOTE && resultCode == RESULT_OK){

        if(data != null){

            String title = data.getStringExtra("title");
            String desc = data.getStringExtra("desc");

            Note mynote = new Note(title,desc);
            noteViewModel.insert(mynote);

            Toast.makeText(getApplicationContext(),"Note saved",Toast.LENGTH_SHORT).show();
        }else{

            Toast.makeText(getApplicationContext(),"Unable to save note",Toast.LENGTH_SHORT).show();
        }
    }
}

在MainActivity中，我使用startActivityForResult方法从AddNotes Activity获取数据。我想知道如何修改我的代码，以便可以将数据添加到在线服务器。请有人指导任何帮助，我们将不胜感激。

谢谢

Answer 1

创建2个存储库

1. NoteRepositoryLocal
2. NoteRepositoryLive

作为您的代码 NoteRepositoryLocal 类似于 NoteRepository添加新的存储库以供 API 调用。 (在您的项目中实现okhttp并改造API调用)

在你的ViewModel中，有两个方法调用。

noteRepositoryLocal.insert(note);
noteRepositoryLive.insert(note);

我没有添加 NoteRepositoryLive 相关代码。如果您有问题，请告诉我。

希望这个答案对你有帮助:)