【发布时间】：2022-01-04 14:29:40
【问题描述】：
我有一个处理外部数据库（sqlite 数据库文件）的项目，我想按如下方式移动到房间数据库
- 数据库 (student_database.db) 的内容最初由第三方应用程序输入，例如 (DB Browser for SQLite)。
- 当我运行我的应用程序时，会创建数据库房间并将数据从 student_database.db 3 我的应用在 Recycler View 中显示来自 (room db) 的数据
- 可以将新数据添加到数据库（房间）
这是我项目的一些文件
@Entity(tableName = "books_table")
public class Book {
@PrimaryKey(autoGenerate = true)
@ColumnInfo(name = "book_id")
private long id;
@ColumnInfo(name = "book_name")
private String name;
@ColumnInfo(name = "all")
private long all;
@ColumnInfo(name = "profile_id")
private long profileId;
public Book() {
}
public Book(String name, long all, long profileId) {
this.name = name;
this.all = all;
this.profileId = profileId;
}
@Dao
public interface BookDAO {
@Insert
void insertBook(Book... book);
@Update
void updateBook(Book... book);
@Entity (tableName = "profiles_table")
public class Profile {
@PrimaryKey(autoGenerate = true)
long id;
@ColumnInfo (name = "profile_name")
String profileName;
public Profile() {
}
public Profile(long id, String profileName) {
this.id = id;
this.profileName = profileName;
}
public Profile(String profileName) {
this.profileName = profileName;
}
@Dao
public interface ProfileDAO {
@Insert
void insertProfile(Profile... profile);
@Update
void updateProfile(Profile... profile);
@Database(entities = {Book.class , Profile.class}, version = 1, exportSchema = false)
public abstract class MyRoomDatabase extends RoomDatabase {
public abstract BookDAO bookDao();
public abstract ProfileDAO profileDAO();
private static volatile MyRoomDatabase INSTANCE;
private static final int NUMBER_OF_THREADS = 4;
static final ExecutorService databaseWriteExecutor =
Executors.newFixedThreadPool(NUMBER_OF_THREADS);
static MyRoomDatabase getDatabase(final Context context) {
if (INSTANCE == null) {
synchronized (MyRoomDatabase.class) {
if (INSTANCE == null) {
INSTANCE = Room.databaseBuilder(context.getApplicationContext(),
MyRoomDatabase.class, "student_prepare_room_database")
.addCallback(sRoomDatabaseCallback)
.build();
}
}
}
return INSTANCE;
}
private static RoomDatabase.Callback sRoomDatabaseCallback = new RoomDatabase.Callback() {
@Override
public void onCreate(@NonNull SupportSQLiteDatabase db) {
super.onCreate(db);
// If you want to keep data through app restarts,
// comment out the following block
databaseWriteExecutor.execute(() -> {
// Populate the database in the background.
// If you want to start with more words, just add them.
});
}
};
}
student_database.db
CREATE TABLE "profile_table" ("id" INTEGER,"profile_name" TEXT,PRIMARY KEY("id"));
[1]：https://i.stack.imgur.com/lDhtR.png
CREATE TABLE "books_table" ("book_id" INTEGER,"book_name" TEXT,"all" INTEGER,"profile_id" INTEGER,PRIMARY KEY("book_id" AUTOINCREMENT));
[2]：https://i.stack.imgur.com/NiuZe.png
【问题讨论】：
标签： java android database sqlite android-room