如何从本地sqlite sugar数据库android

Question

我一直在开发一个应用程序，该应用程序使用Sugar ORM将数据存储在本地sqlite数据库中，并将其也发布到listview中，因此我的任务是从Internet连接为json时直接来自json的直接数据发布listview可用，但是如果连接不可用，那么我必须在数据库中检索已经保存的数据并在列表视图中填充，我已经能够下载并保存数据，但是当网络不可用时，我必须在内部检索它getdatafromlocal方法没有发生

MainActivity.java文件

public class MainActivity extends AppCompatActivity {

private List<Movie> movieList;
private RecyclerView.Adapter adapter;
JSONObject jsonObject;
List<Note> note;
CursorAdapter c;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    RecyclerView mList = findViewById(R.id.main_list);

    movieList = new ArrayList<>();
    adapter = new MovieAdapter(getApplicationContext(), movieList);
    LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);
    linearLayoutManager.setOrientation(LinearLayoutManager.VERTICAL);
    DividerItemDecoration dividerItemDecoration = new DividerItemDecoration(mList.getContext(), linearLayoutManager.getOrientation());

    mList.setHasFixedSize(true);
    mList.setLayoutManager(linearLayoutManager);
    mList.addItemDecoration(dividerItemDecoration);
    mList.setAdapter(adapter);
   // getData();

    if (isNetworkAvailable()) {
        getData();

    }

    else
    {
        getDataFromLocal();
        Toast.makeText(getApplicationContext(),"no internet",Toast.LENGTH_SHORT).show();
        Toast.makeText(getApplicationContext(),"populating from local data",Toast.LENGTH_SHORT).show();
    }
}


private void getData() {
    final ProgressDialog progressDialog = new ProgressDialog(this);
    progressDialog.setMax(100);
    progressDialog.setMessage("Its loading....");
    progressDialog.setTitle("Imageview Example");
    progressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
    progressDialog.show();

    String url = "http://jsonplaceholder.typicode.com/photos";
    JsonArrayRequest jsonArrayRequest = new JsonArrayRequest(url, new 
    Response.Listener<JSONArray>() {
        @Override
        public void onResponse(JSONArray response) {
            for (int i = 0; i < 20; i++) {
                try {
                     jsonObject = response.getJSONObject(i);

                    Movie movie = new Movie();
                    movie.setTitle(jsonObject.getString("title"));
                    movie.setId(jsonObject.getInt("id"));
                    movie.setImage(jsonObject.getString("url"));
                    movie.setAlbumid(jsonObject.getString("albumId"));

     movie.setThumbnailurl(jsonObject.getString("thumbnailUrl"));

                    movieList.add(movie);

                    String Title = jsonObject.getString("title");
                    String Id = jsonObject.getString("id");
                    String Image = jsonObject.getString("url");
                    String Album = jsonObject.getString("albumId");
                    String Thumbnail = jsonObject.getString("thumbnailUrl");

                    note = new ArrayList<>();
                    note.add(new Note(Title,Image,Album,Thumbnail));

                    SugarRecord.saveInTx(note);

                    note.size();

                    copydatabase();
                    Toast.makeText(getApplicationContext(), "Rows Inserted 
        into local storage too", Toast.LENGTH_SHORT).show();


                    Log.e("List Loaded", "imagesList");
                    Log.i("Title", Title);
                    Log.i("Id", Id);
                    Log.i("Image", Image);
                    Log.i("Album", Album);
                    Log.i("Thumbnail", Thumbnail);


                } catch (JSONException e) {
                    e.printStackTrace();
                    progressDialog.dismiss();
                } catch (IOException e) {
                    e.printStackTrace();
                }

            }

            try {
                copydatabase();
            } catch (IOException e) {
                e.printStackTrace();
            }

            adapter.notifyDataSetChanged();
            progressDialog.dismiss();

                       }



    }, new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {
            Log.e("Volley", error.toString());
            progressDialog.dismiss();
        }
    });
    RequestQueue requestQueue = Volley.newRequestQueue(this);
    requestQueue.add(jsonArrayRequest);
  }



private void getDataFromLocal() {

    //what to do next

}


public void copydatabase() throws IOException {

    //File actualFile = null;

    File actualFile= new File(new 
   SugarDb(MainActivity.this).getDB().getPath()); //actual file
    File curentfile  = new File(actualFile.toString()); //new file generated
    Log.e("actualPath", actualFile.toString());


    File newFile = createTempFile("SugarImagesList",".db", 
  Environment.getExternalStorageDirectory());
    newFile.mkdirs();
    if(!newFile.mkdirs()){
        Toast.makeText(MainActivity.this, "file exists", 
 Toast.LENGTH_SHORT).show();
    }

    Log.e("newPath", newFile.toString());

    boolean yes= FileUtils.copyFile(curentfile,newFile);

    if(yes) {
        Log.e("result", "" + true);
        Toast.makeText(getApplicationContext(), "Database Copied to SD card", 
   Toast.LENGTH_SHORT).show();
    }
    }

private boolean isNetworkAvailable() {
    ConnectivityManager connectivityManager
            = (ConnectivityManager) 
getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo activeNetworkInfo = null;
    if (connectivityManager != null) {
        activeNetworkInfo = connectivityManager.getActiveNetworkInfo();
    }
    return activeNetworkInfo != null && activeNetworkInfo.isConnected();
 }

}

Movie.java文件

public class Movie  {


public String title;
public String albumid;
public String thumbnailurl;

public String getAlbumid() {
    return albumid;
}

public void setAlbumid(String albumid) {
    this.albumid = albumid;
}

public String getThumbnailurl() {
    return thumbnailurl;
}

public void setThumbnailurl(String thumbnailurl) {
    this.thumbnailurl = thumbnailurl;
}


public int getId() {
    return id;
}

public void setId( int id) {
    this.id = id;
}

String getImage() {
    return image;
}

public void setImage(String image) {
    this.image = image;
}

private int id;
private String image;

public  Movie() {

}

    public Movie(String title, String image, int id, String albumid, String 
     thumbnailurl ) {
       this.title = title;
       this.image = image;
       this.id = id;
       this.albumid = albumid;
       this.thumbnailurl = thumbnailurl;
   }

public String getTitle() {
    return title;
}

public void setTitle(String title) {
     this.title = title;
 }

 }

Note.java文件

public class Note extends SugarRecord {

public String title;

public String getAlbumid() {
    return albumid;
}

public void setAlbumid(String albumid) {
    this.albumid = albumid;
}

public String getThumbnailurl() {
    return thumbnailurl;
}

public void setThumbnailurl(String thumbnailurl) {
    this.thumbnailurl = thumbnailurl;
}

public String albumid;
public String thumbnailurl;


String getImage() {
    return image;
}

public void setImage(String image) {
    this.image = image;
}

private String image;

public Note(String title ,String image,String albumid, String thumbnailurl) 

   {
       this.title = title;
       this.image = image;
       this.albumid = albumid;
       this.thumbnailurl = thumbnailurl;
   }

  public String getTitle() {
     return title;
   }

   public void setTitle(String title) {
      this.title = title;
    }

    }

MovieAdapter.java类

public class MovieAdapter extends RecyclerView.Adapter<MovieAdapter.ViewHolder> {

private Context context;
private List<Movie> list;
private String link;
private imageDownload image;

MovieAdapter(Context context, List<Movie> list) {
    this.context = context;
    this.list = list;

}


@NonNull
@Override
public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {

    View v = LayoutInflater.from(context).inflate(R.layout.list, parent, false);
    return new ViewHolder(v);

}

@Override
public void onBindViewHolder(@NonNull final MovieAdapter.ViewHolder holder,  int position) {

    Movie movie = list.get(position);


    holder.textTitle.setText(movie.getTitle());
    holder.textId.setText(String.valueOf(movie.getId()));
    holder.textThumb.setText(movie.getThumbnailurl());
    holder.textAlbum.setText(String.valueOf(movie.getAlbumid()));

    Picasso.with(context).load(movie.getImage())
            .into(holder.photo);


    holder.photo.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            link = list.get(holder.getAdapterPosition()+1).getImage();
            image = new imageDownload(context, holder.photo);
            image.execute(link);
            Log.e("image link", link);
            Toast.makeText(context, "image clicked: " + holder.getAdapterPosition(), Toast.LENGTH_LONG).show();
        }
    });

}


@Override
public int getItemCount() {
    return list.size();
}


class ViewHolder extends RecyclerView.ViewHolder {
    TextView textTitle, textId, textThumb, textAlbum;
    ImageView photo;

    ViewHolder(View itemView) {
        super(itemView);

        textTitle = itemView.findViewById(R.id.title_1);
        textId = itemView.findViewById(R.id.id_1);
        textThumb = itemView.findViewById(R.id.thumbnailurl_1);
        textAlbum = itemView.findViewById(R.id.albumid_1);
        photo = itemView.findViewById(R.id.imageview);


    }
}


class imageDownload extends AsyncTask<String, Integer, Bitmap> {
    Context context;
    ImageView imageView;
    Bitmap bitmap;
    InputStream in = null;

    //constructor.
    imageDownload(Context context, ImageView imageView) {
        this.context = context;
        this.imageView = imageView;
    }

    @Override
    protected void onPreExecute() {


    }

    @Override
    protected Bitmap doInBackground(String... params) {
        HttpURLConnection httpURLConnection = null;
        try {
            URL url = new URL(params[0]);
            httpURLConnection = (HttpURLConnection) url.openConnection();
            httpURLConnection.connect();
            in = httpURLConnection.getInputStream();
            BufferedInputStream bufferedInputStream = new 
     BufferedInputStream(in);
            bitmap = BitmapFactory.decodeStream(in);
            in.close();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (httpURLConnection != null) {
                httpURLConnection.disconnect();
            }
        }
        return bitmap;
    }

    @Override
    protected void onPostExecute(Bitmap data) {

        imageView.setImageBitmap(data);
        try {
            try {
                saveImage(data);
            } catch (MalformedURLException e) {
                e.printStackTrace();
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
        // System.out.print(Log.e("Image Data",data.toString()));
    }

    private void saveImage(Bitmap data) throws FileNotFoundException, MalformedURLException {

        File createFolder = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES), "test");

        File saveImage = new File(createFolder, "downloadedImage.jpg");
        try {
            OutputStream outputStream = new FileOutputStream(saveImage);
            data.compress(Bitmap.CompressFormat.JPEG, 100, outputStream);
            outputStream.flush();
            outputStream.close();
        } catch (IOException e) {
            e.printStackTrace();
        }




   }

  }
}

Answer 1

After few trials and errors , i have been able to retrieve the data which was stored in the local database through Sugar ORM, I changed my MainActivity a bit to get the desired results

public class MainActivity extends AppCompatActivity {

EditText firstname;
EditText lastname;
Button button;
Note note;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    firstname=findViewById(R.id.edit1);
    lastname=findViewById(R.id.edit2);
    button=findViewById(R.id.button);
}


@Override
public boolean onCreateOptionsMenu(Menu menu) {

    getMenuInflater().inflate(R.menu.menu_main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {

    int id = item.getItemId();
    return id == R.id.action_settings || super.onOptionsItemSelected(item);

}


public void click(View view) {

    final ProgressDialog progressDialog = new ProgressDialog(this);
    progressDialog.setMax(100);
    progressDialog.setMessage("Its loading....");
    progressDialog.setTitle("Imageview Example");
    progressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
    progressDialog.show();

    String url = "http://jsonplaceholder.typicode.com/photos";
    JsonArrayRequest jsonArrayRequest = new JsonArrayRequest(url, new Response.Listener<JSONArray>() {
        @Override
        public void onResponse(JSONArray response) {
           for (int i = 0; i <1 ; i++) {
                try {
                    JSONObject jsonObject;
                    jsonObject = response.getJSONObject(i);

                    String Title = jsonObject.getString("title");
                    String Id = jsonObject.getString("id");
                    String Image = jsonObject.getString("url");
                    String Album = jsonObject.getString("albumId");
                    String Thumbnail = jsonObject.getString("thumbnailUrl");

                    Log.i("title",Title);
                    Log.i("album",Album);

                    Toast.makeText(getApplicationContext(), Title, Toast.LENGTH_SHORT).show();
                    Toast.makeText(getApplicationContext(), Album, Toast.LENGTH_SHORT).show();

                    note = new Note(Title, Album);
                    note.save();

                   // copydatabase();
                   // Toast.makeText(getApplicationContext(), "Rows Inserted into local storage too", Toast.LENGTH_SHORT).show();
                    progressDialog.dismiss();

                } catch (JSONException e) {
                    e.printStackTrace();
                    progressDialog.dismiss();
                }

            }

           /* try {
                copydatabase();
            } catch (IOException e) {
                e.printStackTrace();
            }*/


        }



    }, new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {
            Log.e("Volley", error.toString());
            progressDialog.dismiss();
        }
    });
    RequestQueue requestQueue = Volley.newRequestQueue(this);
    requestQueue.add(jsonArrayRequest);


}

public void show(View view) {

        String myTitle = note.getTitle();
        String myAlbumid=note.getAlbumId();

    Log.e("title",myTitle);
    Log.e("album",myAlbumid);
}

 public void deletedatabase(View view) {

    boolean check=  MainActivity.this.deleteDatabase("notes.db");

    if(check){
        Toast.makeText(getApplicationContext(),"database deleted",Toast.LENGTH_SHORT).show();
    }

}

public void copydatabase(View view) throws IOException {

    File actualFile = null;

    actualFile= new File(new SugarDb(MainActivity.this).getDB().getPath()); //actual file
    File curentfile  = new File(actualFile.toString()); //new file generated
    Log.e("actualPath", actualFile.toString());


    File newFile = createTempFile("NewSugarAppFiles",".db",Environment.getExternalStorageDirectory());

    Log.e("newPath", newFile.toString());

    boolean yes=FileUtils.copyFile(curentfile,newFile);

    if(yes) {

        Log.e("result", "" + true);
        Toast.makeText(getApplicationContext(), "Database Copied to SD card", Toast.LENGTH_SHORT).show();
    }
  }
}

Here click method would call an API and store the data in the local database and show method would retrieve the stored data.Other classes remain same, I have dropped Recyclerview to simplify things but the data can be stored and retrieved from the Recyclerview also in the same manner as written above.