我正在实施一个天气应用程序，它通过Retrofit和来自GoogleFusedLocationClient的位置从DarkSky获取预测。我的目标是通过应用程序关闭和配置更改来保存UI数据。我使用Room + ViewModel + LiveData和Repository模型实现了它。但是我在我的片段而不是存储库中获取我的位置和预测，目标是将其移动到存储库 这样存储库就会查看数据库，如果它是空的，则从网络中获取数据 我目前的存储库：
public class UIRepository {
private UIDao mUIDao;
private LiveData<List<UIData>> mAllUIData;
UIRepository(Application application) {
PhotoDatabase db = PhotoDatabase.getDatabase(application);
mUIDao = db.uiDao();
mAllUIData = mUIDao.getAllUIData();
}
LiveData<List<UIData>> getAllUIData() {
return mAllUIData;
}
public void insert(UIData uiData) {
new insertAsyncTask(mUIDao).execute(uiData);
}
private static class insertAsyncTask extends AsyncTask<UIData, Void, Void> {
private UIDao mAsyncDao;
insertAsyncTask(UIDao uiDao) {
mAsyncDao = uiDao;
}
@Override
protected Void doInBackground(UIData... uiData) {
mAsyncDao.insert(uiData[0]);
return null;
}
}
}
我可以找到获取位置的单独课程here。而对于预测，它只是改造 我将如何在存储库中组合这些元素？
答案 0 :(得分：2)
我遇到了同样的问题。基本上你想在public class PhotoActivity extends Activity {
ImageView vitb;
Button btcm, btdn;
static final int REQUEST_IMAGE_CAPTURE = 1;
static final int REQUEST_IMAGE_SELECT = 2;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_photo);
vitb = findViewById(R.id.imageView);
btcm = findViewById(R.id.btn_cam);
btdn = findViewById(R.id.btn_back);
btcm.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
selectImage();
}
});
btdn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Drawable drawable = vitb.getDrawable();
Bitmap bitmap = ((BitmapDrawable)drawable).getBitmap();
ByteArrayOutputStream bs = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.JPEG, 0, bs);
byte[] byteArray = bs.toByteArray();
Intent nIntent = new Intent();
nIntent.putExtra("PICTURE", byteArray);
setResult(RESULT_OK, nIntent);
finish();
}
});
}
private void selectImage() {
final CharSequence[] options = { "Take Photo", "Choose from Gallery","Cancel" };
AlertDialog.Builder builder = new AlertDialog.Builder(PhotoActivity.this);
builder.setTitle("Add Photo!");
builder.setItems(options, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int item) {
if (options[item].equals("Take Photo"))
{
Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
startActivityForResult(intent,REQUEST_IMAGE_CAPTURE);
}
else if (options[item].equals("Choose from Gallery"))
{
Intent intent = new Intent(Intent.ACTION_PICK,android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
startActivityForResult(intent,REQUEST_IMAGE_SELECT);
}
else if (options[item].equals("Cancel")) {
dialog.dismiss();
}
}
});
builder.show();
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (resultCode == RESULT_OK) {
if (requestCode == 1) {
Bitmap bmp;
Bundle bundle = data.getExtras();
bmp = (Bitmap)bundle.get("data");
vitb.setImageBitmap(bmp);
}
else if (requestCode == 2) {
Uri selectedImage = data.getData();
String[] filePathColumn = { MediaStore.Images.Media.DATA };
Cursor cursor = getContentResolver().query(selectedImage,
filePathColumn, null, null, null);
cursor.moveToFirst();
int columnIndex = cursor.getColumnIndex(filePathColumn[0]);
String picturePath = cursor.getString(columnIndex);
cursor.close();
//ImageView imageView = findViewById(R.id.imageView);
vitb.setImageBitmap(BitmapFactory.decodeFile(picturePath));
}
}
}
}
中编写逻辑，决定是否从服务器或本地数据库中获取数据。
幸运的是，这是一个非常常见的问题，因此Google提出了NetworkBoundResource类。
public class MainActivity extends Activity{
private static final int REQUEST_CODE1 = 101;
private static final int REQUEST_CODE2 = 102;
Button btnLoc, btnPic;
Button btnSubmit;
TextView tvLoc;
ImageView image;
String phoneNumber = "9000000000";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btnSubmit = findViewById(R.id.btnSubmit);
btnLoc = findViewById(R.id.btnLoc);
btnPic = findViewById(R.id.btnPic);
tvLoc = findViewById(R.id.textView3);
image = findViewById(R.id.img);
btnSubmit.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
try {
SmsManager.getDefault().sendTextMessage(phoneNumber, null, "Hello!", null, null);
}
catch (Exception e) {
AlertDialog.Builder alertDialogBuilder = new
AlertDialog.Builder(MainActivity.this);
AlertDialog dialog = alertDialogBuilder.create();
dialog.setMessage(e.getMessage());
dialog.show();
}
}
});
btnLoc.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View view) {
Intent intent = new Intent(MainActivity.this,LocActivity.class);
startActivityForResult(intent,REQUEST_CODE1);
}
}
);
btnPic.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View view) {
Intent intent = new Intent(MainActivity.this,PhotoActivity.class);
startActivityForResult(intent,REQUEST_CODE2);
}
});
}
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if(resultCode == RESULT_OK){
if(requestCode == REQUEST_CODE1 && data !=null) {
String strMessage = data.getStringExtra("loc");
tvLoc.setText(strMessage);
}
if(requestCode == REQUEST_CODE2 && data !=null) {
Bundle extras = getIntent().getExtras();
byte[] b = extras.getByteArray("PICTURE");
Bitmap bmp = BitmapFactory.decodeByteArray(b, 0, b.length);
image.setImageBitmap(bmp);
}
}
}
}
是一个普通类，它使用Repository的强大功能完成本地数据库和Web服务之间的数据流。