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Use of room database
2022-07-05 05:19:00 【Novice Xiaowang】
1. Guide pack
implementation "androidx.room:room-runtime:2.4.2" annotationProcessor "androidx.room:room-compiler:2.4.2"
2.gradle Middle configuration
javaCompileOptions { annotationProcessorOptions { arguments = ["room.schemaLocation": "$projectDir/schemas".toString()] } }
3. Create data object entity
@Entity
public class User {
@PrimaryKey(autoGenerate = true)
long userId;
@ColumnInfo(name = "username")
String userName;
@ColumnInfo(name = "password")
String password;
public User(@NonNull String userName,@NonNull String password){
this.userName = userName;
this.password = password;
}
}
4. Create the corresponding Dao
@Dao
public interface UserDao {
@Insert
void addUser(User ... user);
@Delete
int deleteUser(User user);
@Update
int updateUser(User user);
@Query("SELECT * FROM user WHERE userID = :id")
User queryUser(long id);
}
5. Create database
//exportSchema = true Support export Room Generated profile
@Database(entities = {User.class},version = 3,exportSchema = true)
public abstract class MyRoomDatabase extends RoomDatabase {
public static String roomName = "user";
public static MyRoomDatabase instance;
public abstract UserDao getUserDao();
public static MyRoomDatabase getInstance(Context context){
if (instance == null){
synchronized (MyRoomDatabase.class){
if (instance == null){
instance = Room.databaseBuilder(context,MyRoomDatabase.class,roomName).allowMainThreadQueries().build();
}
}
}
return instance;
}
}
6. call
MyRoomDatabase.getInstance(this).getUserDao().addUser(new User("wang","lllll"));
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