[移动开发]Android JetPack 之 Room 学习

build.gradle配置

    //room
    implementation 'android.arch.persistence.room:runtime:1.0.0'
    annotationProcessor 'android.arch.persistence.room:compiler:1.0.0'

创建数据库类

@Database(entities = {Note.class},version = 1,exportSchema = false)
public  abstract class NoteDatabase extends RoomDatabase {

    public static final String DB_NAME="note.db";

    private static volatile NoteDatabase instance;

    public static synchronized  NoteDatabase getInstance(Context context){
        if (instance==null){
            instance = create(context);
        }
        return instance;
    }

   public  static NoteDatabase create(final  Context context){
     return Room.databaseBuilder(
             context,
             NoteDatabase.class,
              DB_NAME
     ).build();
   }

   public abstract NoteDao getNoteDao();

创建数据库实体类

@Entity
public class Note {
    @PrimaryKey(autoGenerate = true)
    private int id;
    private String title;
    private String content;
    private Long day_time;
    private int state;
    private String msg;

    public int getId() {
        return id;
    }

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

    public String getTitle() {
        return title;
    }

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

    public String getContent() {
        return content;
    }

    public void setContent(String content) {
        this.content = content;
    }

    public Long getDay_time() {
        return day_time;
    }

    public void setDay_time(Long day_time) {
        this.day_time = day_time;
    }

    public int getState() {
        return state;
    }

    public void setState(int state) {
        this.state = state;
    }

    public String getMsg() {
        return msg;
    }

    public void setMsg(String msg) {
        this.msg = msg;
    }
}

创建操作数据库实体类接口

@Dao
public interface NoteDao {
    @Insert
    void insert(Note...notes);

    @Update
    void update(Note...notes);

    @Delete
    void delete(Note...notes);

    @Query("select * from note")
    List<Note> getAllNote();

    @Query("select * from note where id=:id")
    Note getNote(int id);

}

在Activity 中子线程使用

public class NoteActivity extends AppCompatActivity {

    EditText et_title,et_content;

    Button save_btn;

    NoteDao noteDao;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_note);
        noteDao= NoteDatabase.create(this).getNoteDao();
        initView();
    }



    private void initView() {
        et_title=findViewById(R.id.et_title);
        et_content=findViewById(R.id.et_content);
        save_btn=findViewById(R.id.save_btn);
        save_btn.setOnClickListener(v -> new Thread(saveData).start());
    }

    public Runnable saveData=new Runnable() {
        @Override
        public void run() {
            String title=et_title.getText().toString();
            String content=et_content.getText().toString();
            Long date_time=System.currentTimeMillis();
            Note note=new Note();
            note.setTitle(title);
            note.setContent(content);
            note.setDay_time(date_time);
            noteDao.insert(note);
        }
    };
}