我正在尝试从/ src / main / asset中保存的db文件中复制数据库。 Same创建数据库但不创建任何表。有时它会创建android_metadata表，并在其中输入en_us值。但其他表永远不会被复制。以下是我的代码
09-19 12:17:53.493 32261-32313/com.example.restcalc W/System: ClassLoader referenced unknown path: /data/data/com.example.restcalc/lib
09-19 12:17:54.169 32261-32261/com.example.restcalc I/Choreographer: Skipped 46 frames! The application may be doing too much work on its main thread.
09-19 12:18:03.683 32261-32271/com.example.restcalc I/art: Background sticky concurrent mark sweep GC freed 2831(113KB) AllocSpace objects, 0(0B) LOS objects, 9% free, 2MB/2MB, paused 35.551ms total 58.953ms
09-19 12:18:03.721 32261-32271/com.example.restcalc W/art: Suspending all threads took: 38.121ms
09-19 12:18:07.035 32261-32261/com.example.restcalc W/System.err: java.io.FileNotFoundException: menu_db
09-19 12:18:07.035 32261-32261/com.example.restcalc W/System.err: at android.content.res.AssetManager.openAsset(Native Method)
09-19 12:18:07.035 32261-32261/com.example.restcalc W/System.err: at android.content.res.AssetManager.open(AssetManager.java:313)
09-19 12:18:07.035 32261-32261/com.example.restcalc W/System.err: at android.content.res.AssetManager.open(AssetManager.java:287)
09-19 12:18:07.035 32261-32261/com.example.restcalc W/System.err: at com.example.restcalc.DbOperations$override.copyDatabase(DbOperations.java:36)
09-19 12:18:07.036 32261-32261/com.example.restcalc W/System.err: at com.example.restcalc.DbOperations$override.access$dispatch(DbOperations.java)
09-19 12:18:07.036 32261-32261/com.example.restcalc W/System.err: at com.example.restcalc.DbOperations.copyDatabase(DbOperations.java:0)
09-19 12:18:07.036 32261-32261/com.example.restcalc W/System.err: at com.example.restcalc.MainPage$2.onClick(MainPage.java:153)
09-19 12:18:07.036 32261-32261/com.example.restcalc W/System.err: at android.view.View.performClick(View.java:5198)
09-19 12:18:07.036 32261-32261/com.example.restcalc W/System.err: at android.view.View$PerformClick.run(View.java:21147)
09-19 12:18:07.036 32261-32261/com.example.restcalc W/System.err: at android.os.Handler.handleCallback(Handler.java:739)
09-19 12:18:07.036 32261-32261/com.example.restcalc W/System.err: at android.os.Handler.dispatchMessage(Handler.java:95)
09-19 12:18:07.036 32261-32261/com.example.restcalc W/System.err: at android.os.Looper.loop(Looper.java:148)
09-19 12:18:07.036 32261-32261/com.example.restcalc W/System.err: at android.app.ActivityThread.main(ActivityThread.java:5417)
09-19 12:18:07.036 32261-32261/com.example.restcalc W/System.err: at java.lang.reflect.Method.invoke(Native Method)
09-19 12:18:07.036 32261-32261/com.example.restcalc W/System.err: at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
09-19 12:18:07.036 32261-32261/com.example.restcalc W/System.err: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
09-19 12:18:08.038 32261-32261/com.example.restcalc I/Choreographer: Skipped 59 frames! The application may be doing too much work on its main thread.
09-19 12:18:08.507 32261-32267/com.example.restcalc W/art: Suspending all threads took: 17.206ms
09-19 12:18:45.535 32261-32267/com.example.restcalc W/art: Suspending all threads took: 6.309ms
09-19 12:21:30.767 32261-32267/com.example.restcalc W/art: Suspending all threads took: 6.321ms
09-19 12:21:46.789 32261-32267/com.example.restcalc W/art: Suspending all threads took: 5.514ms
--------- beginning of system
09-19 12:22:32.849 32261-32267/com.example.restcalc W/art: Suspending all threads took: 5.377ms
09-19 12:23:05.924 32261-32267/com.example.restcalc W/art: Suspending all threads took: 9.828ms
09-19 12:27:40.675 32261-32267/com.example.restcalc W/art: Suspending all threads took: 6.375ms
09-19 12:30:18.409 32261-32267/com.example.restcalc W/art: Suspending all threads took: 10.667ms
09-19 12:31:43.045 32261-32267/com.example.restcalc W/art: Suspending all threads took: 11.935ms
DbOperation.java
package com.example.restcalc;
import android.content.Context;
import android.database.Cursor;
import android.database.DatabaseErrorHandler;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
import android.widget.Toast;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
/**
* Created by User1 on 24/08/2016.
*/
public class DbOperations extends SQLiteOpenHelper {
public static final String DB_PATH = "data/data/com.example.restcalc/databases/";
private static final String LOG = "";
private Context context;
private SQLiteDatabase mDatabase;
public DbOperations(Context context) {
super(context, DbData.DATABASE_NAME, null, 1);
this.context = context;
}
public boolean copyDatabase (Context context) {
try {
// Open your local db as the input stream
InputStream inputStream = context.getAssets().open(DbData.DATABASE_NAME);
// Path to the just created empty db
String outFilename = DB_PATH + DbData.DATABASE_NAME;
// Open the empty db as the output stream
OutputStream outputStream = new FileOutputStream(outFilename);
byte[] buffer = new byte[1024];
int length = 0;
while ((length = inputStream.read(buffer)) > 0) {
outputStream.write(buffer, 0, length);
}
outputStream.flush();
outputStream.close();
return true;
} catch (IOException e) {
e.printStackTrace();
return false;
}
}
@Override
public void onCreate(SQLiteDatabase sqLiteDatabase) {
}
@Override
public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {
}
public void openDatabase () {
String dbPath = context.getDatabasePath(DbData.DATABASE_NAME).getPath();
if (mDatabase != null && mDatabase.isOpen()) {
return;
}
mDatabase = SQLiteDatabase.openDatabase(dbPath, null, SQLiteDatabase.OPEN_READONLY);
}
public void closeDatabase () {
if (mDatabase != null) {
mDatabase.close();
}
}
public Cursor retrieveData (DbOperations dbOperations) {
SQLiteDatabase sqldb = dbOperations.getReadableDatabase();
String selectQuery = "SELECT item_rate FROM " + DbData.menuItem_table
+ " WHERE item_number = " + MainPage.item_number;
Log.d(LOG,selectQuery);
Cursor cursor = sqldb.rawQuery(selectQuery, null);
return cursor;
}
}
MainPage.java
//calling the DbOperations
DbOperations dbOperations = new DbOperations(context);
//Check database exists
File database = getApplicationContext().getDatabasePath(DbData.DATABASE_NAME);
if (false == database.exists()) {
//copy db
if (dbOperations.copyDatabase(getApplicationContext())) {
Toast.makeText(context, "Copy Database Success", Toast.LENGTH_LONG).show();
} else {
Toast.makeText(context, "copy Database Error", Toast.LENGTH_LONG).show();
return;
}
} else {
Toast.makeText(context, "Database Exists", Toast.LENGTH_LONG).show();
Cursor cursor = null;
cursor = dbOperations.retrieveData(dbOperations);
if (cursor.moveToFirst()) {
itemRate = cursor.getInt(0);
int a = itemRate * Integer.valueOf(itemQty.getText().toString());
a = a + 40; // add service charge
intent.putExtra("Total", a);
startActivity(intent);
} else {
Toast.makeText(getBaseContext(),"Item Rate Not Found", Toast.LENGTH_LONG).show();
}
}
}
答案 0 :(得分：0)
我在sqlite浏览器中再次复制了数据库并使用.sqlite生成了该文件。我将此文件放在assets文件夹中，并将数据库名称的名称更改为menu_db.sqlite。有效。我不确定这是否是正确的答案，但我在这里看到了很多这样的问题。对于那些它可能有用。