我正在关注此链接以打开与数据库的连接。但是，当我尝试打开它时，它会抛出一个异常，表示errorCopyingDatabase。我的数据库大小约为20MB。是因为它没有从Assets文件夹复制到内存或其他问题的大小。我确定我的代码很好，我还仔细检查了所有路径（一切似乎都很好）。我得到以下异常：
12-14 04:44:45.471: E/AndroidRuntime(512): java.lang.Error: ErrorCopyingDataBase
12-14 04:44:45.471: E/AndroidRuntime(512): at com.bondsms.db.DBHelper.createDataBase(DBHelper.java:42)
12-14 04:44:45.471: E/AndroidRuntime(512): at com.bondsms.db.DBAdapter.createDatabase(DBAdapter.java:37)
12-14 04:44:45.471: E/AndroidRuntime(512): at com.bondsms.BSGroupsActivity.loadAllGroupsFromDB(BSGroupsActivity.java:98)
12-14 04:44:45.471: E/AndroidRuntime(512): at com.bondsms.BSGroupsActivity.onCreate(BSGroupsActivity.java:55)
12-14 04:44:45.471: E/AndroidRuntime(512): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
12-14 04:44:45.471: E/AndroidRuntime(512): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
12-14 04:44:45.471: E/AndroidRuntime(512): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
12-14 04:44:45.471: E/AndroidRuntime(512): at android.app.ActivityThread.access$2300(ActivityThread.java:125)
12-14 04:44:45.471: E/AndroidRuntime(512): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
12-14 04:44:45.471: E/AndroidRuntime(512): at android.os.Handler.dispatchMessage(Handler.java:99)
12-14 04:44:45.471: E/AndroidRuntime(512): at android.os.Looper.loop(Looper.java:123)
12-14 04:44:45.471: E/AndroidRuntime(512): at android.app.ActivityThread.main(ActivityThread.java:4627)
12-14 04:44:45.471: E/AndroidRuntime(512): at java.lang.reflect.Method.invokeNative(Native Method)
12-14 04:44:45.471: E/AndroidRuntime(512): at java.lang.reflect.Method.invoke(Method.java:521)
12-14 04:44:45.471: E/AndroidRuntime(512): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
12-14 04:44:45.471: E/AndroidRuntime(512): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
12-14 04:44:45.471: E/AndroidRuntime(512): at dalvik.system.NativeStart.main(Native Method)
答案 0 :(得分：0)
我已经花了很多时间从资产中复制数据库，这是我要复制的类，它对我来说很好用，你可以使用它，也许它有帮助（记得改变DB_PATH =“/ data / data / [你的包裹] / databases /“。和DB_NAME =资产中你的数据名称。”
public class DatabaseController extends SQLiteOpenHelper {
// The Android's default system path of your application database.
private static String DB_PATH = "/data/data/com.hanoifood/databases/";
private static final String DB_NAME = "HanoiFood.sqlite";
private SQLiteDatabase myDataBase;
private final Context myContext;
/**
* Constructor Takes and keeps a reference of the passed context in order to
* access to the application assets and resources.
*
* @param context
*/
public DatabaseController(Context context) {
super(context, DB_NAME, null, 1);
this.myContext = context;
try {
createDataBase();
} catch (IOException ioe) {
throw new Error("Unable to create database");
}
}
/**
* Creates a empty database on the system and rewrites it with your own
* database.
* */
public void createDataBase() throws IOException {
boolean dbExist = checkDataBase();
if (dbExist) {
// do nothing - database already exist
myDataBase = getWritableDatabase();
} else {
myDataBase = getWritableDatabase();
try {
copyDataBase();
} catch (IOException e) {
throw new Error("Error copying database");
}
}
}
/**
* Check if the database already exist to avoid re-copying the file each
* time you open the application.
*
* @return true if it exists, false if it doesn't
*/
private boolean checkDataBase() {
SQLiteDatabase checkDB = null;
try {
String myPath = DB_PATH + DB_NAME;
checkDB = SQLiteDatabase.openDatabase(myPath, null,
SQLiteDatabase.OPEN_READONLY);
} catch (Exception e) {
// database does't exist yet.
}
if (checkDB != null) {
checkDB.close();
}
return checkDB != null ? true : false;
}
/**
* Copies your database from your local assets-folder to the just created
* empty database in the system folder, from where it can be accessed and
* handled. This is done by transfering bytestream.
* */
private void copyDataBase() throws IOException {
// Open your local db as the input stream
InputStream myInput = myContext.getAssets().open(DB_NAME);
// Path to the just created empty db
String outFileName = DB_PATH + DB_NAME;
// Open the empty db as the output stream
OutputStream myOutput = new FileOutputStream(outFileName);
// transfer bytes from the inputfile to the outputfile
byte[] buffer = new byte[1024];
int length;
while ((length = myInput.read(buffer)) > 0) {
myOutput.write(buffer, 0, length);
}
// Close the streams
myOutput.flush();
myOutput.close();
myInput.close();
}
public void openDataBase() throws SQLException {
// Open the database
String myPath = DB_PATH + DB_NAME;
myDataBase = SQLiteDatabase.openDatabase(myPath, null,
SQLiteDatabase.OPEN_READWRITE);
}
public Cursor query(String table, String[] columns, String selection,
String[] selectionArgs, String groupBy, String having,
String orderBy) {
myDataBase = getWritableDatabase();
Cursor cursor = myDataBase.query(table, columns, selection,
selectionArgs, groupBy, having, orderBy);
if (cursor == null) {
return null;
} else if (!cursor.moveToFirst()) {
cursor.close();
return null;
}
return cursor;
}
public long insert(String table, String nullColumnHack, ContentValues values) {
long insertRet = myDataBase.insert(table, nullColumnHack, values);
if (insertRet == -1) {
Log.d("DungHV", "Insert db error");
}
return insertRet;
}
@Override
public synchronized void close() {
if (myDataBase != null)
myDataBase.close();
super.close();
}
@Override
public void onCreate(SQLiteDatabase db) {
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
}
}
在您的Activity简单调用中：
DatabaseContrller mdb = new DatabaseController(getApplicationContext());