我在项目中有2个数据库,其中一个是在我打开应用程序时创建的,另一个是随资产提供的。
生成DaoSession时,会为所有模型创建DaoSession。
gradle文件中的Schema也用于两个数据库
如何区分2个数据库及其模式?
答案 0 :(得分:6)
您需要创建两个扩展org.greenrobot.greendao.database.DatabaseOpenHelper
的不同类。这两个不同的类DevOpenHelperForDatabase1
和DevOpenHelperForDatabase2
将处理db实现的I / O.从下面的代码中可以很容易地理解,创建具有相同和不同模式或表或实体的两个不同的数据库:
public class App extends Application {
private DaoSessionForDatabase1 mDaoSessionForDatabase1;
private DaoSessionForDatabase2 mDaoSessionForDatabase2;
@Override
public void onCreate() {
super.onCreate();
//Create Doa session for database1
DevOpenHelperForDatabase1 devOpenHelperForDatabase1 = new DevOpenHelperForDatabase1(this,
"database1-db");
Database databse1 = devOpenHelperForDatabase1.getWritableDb();
mDaoSessionForDatabase1 = new DaoMasterForDatabase1(databse1).newSession();
//Create Doa session for database2
DevOpenHelperForDatabase2 devOpenHelperForDatabase2 = new DevOpenHelperForDatabase2(this,
"database2-db");
Database databse2 = devOpenHelperForDatabase2.getWritableDb();
mDaoSessionForDatabase2 = new DaoMasterForDatabase2(databse2).newSession();
}
public DaoSessionForDatabase1 getDaoSessioForDatabase1() {
return mDaoSessionForDatabase1;
}
public DaoSessionForDatabase2 getDaoSessioForDatabase2() {
return mDaoSessionForDatabase2;
}
}
您可以访问与Activity相同的不同架构或表或实体作为示例:
// get the Schema1 DAO for Database1
DaoSessionForDatabase1 daoSessionForDatabase1 = ((App) getApplication()).getDaoSessioForDatabase1();
Schema1Dao schema1Dao = daoSessionForDatabase1.getSchema1Dao();
// get the Schema2 DAO for Database2
DaoSessionForDatabase2 daoSessionForDatabase2 = ((App) getApplication()).getDaoSessioForDatabase2();
Schema2Dao schema2Dao = daoSessionForDatabase2.getSchema2Dao();
更新2 ::以上内容可以放弃,但方法也是一样的。根据以下评论中的讨论完成更新:
中进行了更改package org.greenrobot.greendao.example;
import android.app.Application;
import org.greenrobot.greendao.database.Database;
import org.greenrobot.greendao.example.DaoMaster.DevOpenHelper;
public class App extends Application {
/** A flag to show how easily you can switch from standard SQLite to the encrypted SQLCipher. */
public static final boolean ENCRYPTED = true;
private DaoSession daoSession;
private DaoSession daoSession1;
@Override
public void onCreate() {
super.onCreate();
DevOpenHelper helper = new DevOpenHelper(this, ENCRYPTED ? "notes-db-encrypted" : "notes-db");
Database db = ENCRYPTED ? helper.getEncryptedWritableDb("super-secret") : helper.getWritableDb();
daoSession = new DaoMaster(db).newSession();
DevOpenHelper helper1 = new DevOpenHelper(this, "notes1-db");
Database db1 = helper1.getWritableDb();
daoSession1 = new DaoMaster(db1).newSession();
}
public DaoSession getDaoSession() {
return daoSession;
}
public DaoSession getDaoSession1() {
return daoSession1;
}
}
现在在NoteActivity.java
//Add below class members
private static boolean switchDbBetweenOneAndTwo = false;
private NoteDao noteDao2;
private Query<Note> notesQuery2;
//In on craete add the following as the last statement after notesQuery = noteDao.queryBuilder().orderAsc(NoteDao.Properties.Text).build();
@Override
public void onCreate(Bundle savedInstanceState) {
......
Log.d("Database 1", "notesQuery.list()="+notesQuery.list().toString());
// get the note DAO for Database2
DaoSession daoSessionForDb2 = ((App) getApplication()).getDaoSession1();
noteDao2 = daoSessionForDb2.getNoteDao();
// query all notes, sorted a-z by their text
notesQuery2 = noteDao2.queryBuilder().orderAsc(NoteDao.Properties.Text).build();
Log.d("Database 2", "notesQuery2.list()="+notesQuery2.list().toString());
updateNotes();
}
//Replace updateNotes as
private void updateNotes() {
List<Note> notes = notesQuery.list();
List<Note> notes2 = notesQuery2.list();
notes.addAll(notes2);
notesAdapter.setNotes(notes);
}
//Replace addNote as
private void addNote() {
String noteText = editText.getText().toString();
editText.setText("");
final DateFormat df = DateFormat.getDateTimeInstance(DateFormat.MEDIUM, DateFormat.MEDIUM);
String comment = "Added on " + df.format(new Date());
Note note = new Note();
note.setText(noteText);
note.setComment(comment);
note.setDate(new Date());
note.setType(NoteType.TEXT);
if(!switchDbBetweenOneAndTwo){
note.setText(noteText + " In database 1");
noteDao.insert(note);
}
else {
note.setText(noteText + " In database 2");
noteDao2.insert(note);
}
Log.d("DaoExample", "Inserted new note, ID: " + note.getId());
switchDbBetweenOneAndTwo = true;
updateNotes();
}
我没有更改gradle文件或添加任何内容,因为它对我没有任何意义。
答案 1 :(得分:1)
对于Greendao第3版,不可能有超过1个架构。
github.com/greenrobot/greenDAO/issues/356
正如他们在网站上所写的那样:
请注意,多个架构为currently not supported when using the Gradle plugin 。目前,继续使用您的发电机 项目
他们已将此功能添加到新的GreenDao中。