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room android sqlite

M4Y 2022-07-14 阅读 95
androididejavaAndroid移动开发yyds干货盘点

detail:使用room框架，做一个增删查改的android版本sqlite

step1: C:\Users\HHL\AndroidStudioProjects\MyApplication8\app\src\main AppDatabase

package com.example.myapplication;

import androidx.room.Database;
import androidx.room.RoomDatabase;

/**
 * @author acampbell
 */
@Database(exportSchema = false, entities = {Note.class, Category.class}, version = 1)
public abstract class AppDatabase extends RoomDatabase {

    public static final String DB_NAME = "app_db";

    public abstract NoteDao getNoteDao();

    public abstract CategoryDao getCategoryDao();

}

step2: Category

package com.example.myapplication;

import androidx.room.ColumnInfo;
import androidx.room.Entity;
import androidx.room.PrimaryKey;

/**
 * @author acampbell
 */
@Entity(tableName = "category")
public class Category {

    @PrimaryKey(autoGenerate = true)
    @ColumnInfo(name = "id")
    private long id;
    @ColumnInfo(name = "name")
    private String name;

    public long getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return name;
    }
}

step3： CategoryAdapter

package com.example.myapplication;

import android.content.Context;
import android.widget.ArrayAdapter;

import androidx.annotation.LayoutRes;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;

import java.util.List;

/**
 * @author acampbell
 */
public class CategoryAdapter extends ArrayAdapter<Category> {

    private final List<Category> categories;

    public CategoryAdapter(@NonNull Context context,
                           @LayoutRes int resource,
                           List<Category> categories) {
        super(context, resource, categories);
        this.categories = categories;
    }

    @Override
    public int getCount() {
        return super.getCount() + 1;
    }

    @Nullable
    @Override
    public Category getItem(int position) {
        if (position == 0) {
            Category category = new Category();
            category.setId(0);
            category.setName(getContext().getString(R.string.create_new_category));
            return category;
        }
        return super.getItem(position - 1);
    }

    public int getCategoryPosition(@Nullable Long categoryId) {
        if (categoryId != null) {
            for (int i = 0; i < categories.size(); i++) {
                if (categoryId == categories.get(i).getId()) {
                    return i + 1;
                }
            }
        }
        return -1;
    }
}

step4: CategoryDao

package com.example.myapplication;

import androidx.room.Dao;
import androidx.room.Delete;
import androidx.room.Insert;
import androidx.room.Query;

import java.util.List;

/**
 * @author acampbell
 */
@Dao
public interface CategoryDao {

    @Insert
    long insert(Category category);

    @Query("SELECT * FROM category")
    List<Category> getAll();

    @Delete
    void deleteAll(Category categories);
}

step5: CategoryNote

package com.example.myapplication;

public class CategoryNote extends Note {

    private String categoryName;

    public String getCategoryName() {
        return categoryName;
    }

    public void setCategoryName(String categoryName) {
        this.categoryName = categoryName;
    }
}

step6: EditNoteActivity

package com.example.myapplication;

import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.Spinner;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;
import androidx.room.Room;
import java.util.List;

public class EditNoteActivity extends AppCompatActivity implements View.OnClickListener, AdapterView.OnItemSelectedListener {

    public static final String EXTRA_NOTE_ID = "EXTRA_NOTE_ID";

    private AppDatabase db;
    private TextView title;
    private TextView description;
    private TextView category;
    private Spinner categorySpinner;
    private CategoryAdapter adapter;
    private Long noteId;
    private Note note;

    public static Bundle newInstanceBundle(long noteId) {
        Bundle bundle = new Bundle();
        bundle.putLong(EXTRA_NOTE_ID, noteId);
        return bundle;
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_edit_note);

        Intent intent = getIntent();
        if (intent.hasExtra(EXTRA_NOTE_ID)) {
            noteId = intent.getLongExtra(EXTRA_NOTE_ID, -1);
        }

        db = Room.databaseBuilder(this, AppDatabase.class, AppDatabase.DB_NAME).build();
        title = (TextView) findViewById(R.id.title);
        description = (TextView) findViewById(R.id.description);
        category = (TextView) findViewById(R.id.category);
        findViewById(R.id.save).setOnClickListener(this);

        categorySpinner = (Spinner) findViewById(R.id.category_spinner);
        categorySpinner.setOnItemSelectedListener(this);
    }

    @Override
    protected void onResume() {
        super.onResume();
        loadCategories();
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.save:
                saveNote();
                break;
        }
    }

    @Override
    public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
        if (position == 0) {
            category.setVisibility(View.VISIBLE);
        } else {
            category.setVisibility(View.GONE);
        }
    }

    @Override
    public void onNothingSelected(AdapterView<?> parent) {
    }

    private void loadNote() {
        new AsyncTask<Long, Void, CategoryNote>() {
            @Override
            protected CategoryNote doInBackground(Long... params) {
                return db.getNoteDao().getCategoryNote(params[0]);
            }

            @Override
            protected void onPostExecute(CategoryNote note) {
                setNote(note);
            }
        }.execute(noteId);
    }

    private void setNote(Note note) {
        this.note = note;
        title.setText(note.getTitle());
        description.setText(note.getDescription());
        int categoryPosition = adapter.getCategoryPosition(note.getCategoryId());
        if (categoryPosition > 0) {
            categorySpinner.setSelection(categoryPosition);
        }
    }

    private void loadCategories() {
        new AsyncTask<Void, Void, List<Category>>() {
            @Override
            protected List<Category> doInBackground(Void... params) {
                return db.getCategoryDao().getAll();
            }

            @Override
            protected void onPostExecute(List<Category> adapterCategories) {
                setCategories(adapterCategories);
                if (noteId != null) {
                    loadNote();
                }
            }
        }.execute();
    }

    private void setCategories(List<Category> categories) {
        adapter = new CategoryAdapter(this, android.R.layout.simple_list_item_1, categories);
        categorySpinner.setAdapter(adapter);
    }

    private void saveNote() {
        if (note == null) {
            note = new Note();
        }
        note.setTitle(title.getText().toString().trim());
        note.setDescription(description.getText().toString().trim());
        final String categoryName = category.getText().toString().trim();
        Category selectedCategory = adapter.getItem(categorySpinner.getSelectedItemPosition());
        final Long selectedCategoryId = (selectedCategory == null || selectedCategory.getId() <= 0) ? null : selectedCategory.getId();

        new AsyncTask<Note, Void, Void>() {
            @Override
            protected Void doInBackground(Note... params) {
                Note saveNote = params[0];
                if (selectedCategoryId != null) {
                    saveNote.setCategoryId(selectedCategoryId);
                } else if (categoryName.length() > 0) {
                    Category category = new Category();
                    category.setName(categoryName);
                    long categoryId = db.getCategoryDao().insert(category);
                    saveNote.setCategoryId(categoryId);
                } else {
                    note.setCategoryId(null);
                }
                if (saveNote.getId() > 0) {
                    db.getNoteDao().updateAll(saveNote);
                } else {
                    db.getNoteDao().insertAll(saveNote);
                }
                return null;
            }

            @Override
            protected void onPostExecute(Void aVoid) {
                setResult(RESULT_OK);
                finish();
            }
        }.execute(note);
    }
}

step7: Note

package com.example.myapplication;

import androidx.annotation.Nullable;
import androidx.room.ColumnInfo;
import androidx.room.Entity;
import androidx.room.PrimaryKey;

/**
 * @author acampbell
 */
@Entity(tableName = "note")
public class Note {

    @PrimaryKey(autoGenerate = true)
    @ColumnInfo(name = "id")
    private long id;
    @ColumnInfo(name = "title")
    private String title;
    @ColumnInfo(name = "description")
    private String description;
    @ColumnInfo(name = "category_id")
    private Long categoryId;

    public long getId() {
        return id;
    }

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

    public String getTitle() {
        return title;
    }

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

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    @Nullable
    public Long getCategoryId() {
        return categoryId;
    }

    public void setCategoryId(@Nullable Long categoryId) {
        this.categoryId = categoryId;
    }

}

step8: NoteAdapter

package com.example.myapplication;

import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

import java.util.ArrayList;
import java.util.List;

/**
 * @author acampbell
 */
public class NoteAdapter extends RecyclerView.Adapter<NoteAdapter.ViewHolder> {

    private List<CategoryNote> notes = new ArrayList<>();
    private final ActionCallback callback;

    public NoteAdapter(@NonNull ActionCallback callback) {
        this.callback = callback;
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_note, parent, false);
        final ViewHolder viewHolder = new ViewHolder(view);
        view.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                callback.onEdit(notes.get(viewHolder.getAdapterPosition()));
            }
        });
        return viewHolder;
    }

    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        CategoryNote note = notes.get(position);
        holder.title.setText(note.getTitle());

        holder.id.setText(String.valueOf(note.getId()));

        holder.description.setText(note.getDescription());
        holder.category.setText(note.getCategoryName());
    }

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

    public CategoryNote getNote(int position) {
        return notes.get(position);
    }

    public void setNotes(@NonNull List<CategoryNote> notes) {
        this.notes = notes;
        notifyDataSetChanged();
    }

    public interface ActionCallback {
        void onEdit(CategoryNote note);
    }

    static class ViewHolder extends RecyclerView.ViewHolder {
        TextView title, description, category, id;

        ViewHolder(View itemView) {
            super(itemView);
            title = (TextView) itemView.findViewById(R.id.title);
            id = (TextView) itemView.findViewById(R.id.id);

            description = (TextView) itemView.findViewById(R.id.description);
            category = (TextView) itemView.findViewById(R.id.category);
        }
    }
}

step9: NoteDao

package com.example.myapplication;

import androidx.room.Dao;
import androidx.room.Delete;
import androidx.room.Insert;
import androidx.room.Query;
import androidx.room.Update;

import java.util.List;

/**
 * @author acampbell
 */
@Dao
public interface NoteDao {

    @Insert
    void insertAll(Note Notes);

    @Update
    void updateAll(Note Notes);

    @Query("SELECT * FROM Note")
    List<Note> getAll();

    @Query("SELECT Note.id, Note.title, Note.description, category.name as categoryName " +
            "FROM Note " +
            "LEFT JOIN category ON Note.category_id = category.id")
    List<CategoryNote> getCategoryNotes();

    @Query("SELECT Note.id, Note.title, Note.description, Note.category_id " +
            "FROM Note " +
            "LEFT JOIN category ON Note.category_id = category.id " +
            "WHERE Note.id = :NoteId")
    CategoryNote getCategoryNote(long NoteId);

    @Delete
    void deleteAll(Note... Notes);
}

step10: TextActivity

package com.example.myapplication;

import android.annotation.SuppressLint;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.View;

import androidx.appcompat.app.AppCompatActivity;
import androidx.cardview.widget.CardView;
import androidx.constraintlayout.widget.ConstraintLayout;
import androidx.recyclerview.widget.ItemTouchHelper;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import androidx.room.Room;

import com.google.android.material.floatingactionbutton.FloatingActionButton;
import com.google.android.material.textfield.TextInputEditText;
import com.google.android.material.textfield.TextInputLayout;

import java.util.List;

public class TextActivity extends AppCompatActivity
        implements NoteAdapter.ActionCallback, View.OnClickListener {

    FloatingActionButton mFloatingActionButton;
    ConstraintLayout mConstraintLayout;
    TextInputEditText mTextInputEditText;
    CardView mCardView;
    TextInputLayout mTextInputLayout;

    private NoteAdapter adapter;
    private AppDatabase db;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        db = Room.databaseBuilder(this, AppDatabase.class, AppDatabase.DB_NAME).build();
        findViewById(R.id.add).setOnClickListener(this);
        adapter = new NoteAdapter(this);
        RecyclerView recyclerView = (RecyclerView) findViewById(R.id.recycler_view);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        recyclerView.setAdapter(adapter);
        ItemTouchHelper.SimpleCallback callback = new ItemTouchHelper.SimpleCallback(0, ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT) {
            @Override
            public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {
                return false;
            }

            @Override
            public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {
                deleteNote(adapter.getNote(viewHolder.getAdapterPosition()));
            }
        };
        ItemTouchHelper itemTouchHelper = new ItemTouchHelper(callback);
        itemTouchHelper.attachToRecyclerView(recyclerView);
    }

    @Override
    protected void onResume() {
        super.onResume();
        loadNotes();
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.add:
                startActivity(new Intent(this, EditNoteActivity.class));
                break;
        }
    }

    private void loadNotes() {
        new AsyncTask<Void, Void, List<CategoryNote>>() {
            @Override
            protected List<CategoryNote> doInBackground(Void... params) {
                return db.getNoteDao().getCategoryNotes();
            }

            @Override
            protected void onPostExecute(List<CategoryNote> notes) {
                adapter.setNotes(notes);
            }
        }.execute();
    }

    @SuppressLint("StaticFieldLeak")
    private void deleteNote(Note note) {
        new AsyncTask<Note, Void, Void>() {
            @Override
            protected Void doInBackground(Note... params) {
                db.getNoteDao().deleteAll(params);
                return null;
            }

            @Override
            protected void onPostExecute(Void aVoid) {
                loadNotes();
            }
        }.execute(note);
    }

    @Override
    public void onPointerCaptureChanged(boolean hasCapture) {

    }

    @Override
    public void onEdit(CategoryNote note) {
        Intent intent = new Intent(this, EditNoteActivity.class);
        intent.putExtras(EditNoteActivity.newInstanceBundle(note.getId()));
        startActivity(intent);
    }
}

step11: build 引用

    def room_version = "2.2.5"
    implementation "androidx.room:room-runtime:$room_version"
    annotationProcessor "androidx.room:room-compiler:$room_version"
    implementation 'androidx.recyclerview:recyclerview:1.1.0'
    implementation 'androidx.lifecycle:lifecycle-extensions:2.2.0'

end

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