如何使用GreenDao ORM库从Android中的资产创建数据库
我正在使用如何使用GreenDao ORM库从Android中的资产创建数据库,android,orm,dao,greendao,Android,Orm,Dao,Greendao,我正在使用GreenDaoorm库来创建数据库，它与从代码中创建数据库的第一个示例配合得很好 现在的问题是，我找不到任何文档或与数据库从Assets文件夹复制到内存中的数据库相关的任何内容。接受的答案提供了一个解决方案，但它只是部分正确。看看我贴在下面的课程。这是greenDao的OpenHelper类的扩展。下面是它的使用示例，以及如何使用它而不是OpenHelper或DevPenHelper来管理sqlite数据库的副本 package com.example; import java.i
GreenDao现在的问题是，我找不到任何文档或与数据库从Assets文件夹复制到内存中的数据库相关的任何内容。接受的答案提供了一个解决方案，但它只是部分正确。看看我贴在下面的课程。这是greenDao的OpenHelper类的扩展。下面是它的使用示例，以及如何使用它而不是OpenHelper或DevPenHelper来管理sqlite数据库的副本
package com.example;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import com.example.R;
import com.example.DaoMaster.OpenHelper;
public class DatabaseOpenHelper extends OpenHelper {
private Context context;
private SQLiteDatabase sqliteDatabase;
private static String DB_PATH;
private static String DB_NAME;
public DatabaseOpenHelper(Context context, String name, CursorFactory factory) {
super(context, name, factory);
this.context = context;
this.DB_NAME = name;
this.DB_PATH = context.getString(R.string.DB_PATH);
try {
createDataBase();
} catch (Exception ioe) {
throw new Error("Unable to create database");
}
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
}
/** Open Database for Use */
public void openDatabase() {
String databasePath = DB_PATH + DB_NAME;
sqliteDatabase = SQLiteDatabase.openDatabase(databasePath, null,
(SQLiteDatabase.OPEN_READWRITE));
}
/** Close Database after use */
@Override
public synchronized void close() {
if ((sqliteDatabase != null) && sqliteDatabase.isOpen()) {
sqliteDatabase.close();
}
super.close();
}
/** Get database instance for use */
public SQLiteDatabase getSqliteDatabase() {
return sqliteDatabase;
}
/** Create new database if not present */
public void createDataBase() {
SQLiteDatabase sqliteDatabase = null;
if (databaseExists()) {
/* Check for Upgrade */
} else {
/* Database does not exists create blank database */
sqliteDatabase = this.getReadableDatabase();
sqliteDatabase.close();
copyDataBase();
}
}
/** Check Database if it exists */
private boolean databaseExists() {
SQLiteDatabase sqliteDatabase = null;
try {
String databasePath = DB_PATH + DB_NAME;
sqliteDatabase = SQLiteDatabase.openDatabase(databasePath, null,
SQLiteDatabase.OPEN_READONLY);
} catch (SQLiteException e) {
e.printStackTrace();
}
if (sqliteDatabase != null) {
sqliteDatabase.close();
}
return sqliteDatabase != null ? true : false;
}
/**
* Copy existing database file in system
*/
public void copyDataBase() {
int length;
byte[] buffer = new byte[1024];
String databasePath = DB_PATH + DB_NAME;
try {
InputStream databaseInputFile = this.context.getAssets().open(DB_NAME+".sqlite");
OutputStream databaseOutputFile = new FileOutputStream(databasePath);
while ((length = databaseInputFile.read(buffer)) > 0) {
databaseOutputFile.write(buffer, 0, length);
databaseOutputFile.flush();
}
databaseInputFile.close();
databaseOutputFile.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
DatabaseOpenHelper helper = new DatabaseOpenHelper(this, "db", null);
db = helper.getWritableDatabase();
daoMaster = new DaoMaster(db);
daoSession = daoMaster.newSession();
www.rewindesign.com/blog/using-your-own-sqlite-database-in-android-applications/阅读此文我知道从
SqliteOpenHelperGreenDaoORM