Question

我使用下面的DBHelper类将sqlite db从 assets 复制到sdcard。

它在模拟器和其他Android设备上完美复制数据库但是当我尝试从任何Android设备通过应用程序访问数据库时，应用程序崩溃，而在模拟器上它工作正常。

DBHelper.java： - 的

public class DBHelper extends SQLiteOpenHelper {

public SQLiteDatabase database = null;
public File databaseFile;
public static String databaseName = "Db1.sqlite";
public String databasePath = "";

Context mContext;

public DBHelper(Context paramContext) {

    super(paramContext, databaseName, null, 1);
    this.mContext = paramContext;

    this.databasePath =  (Environment.getExternalStorageDirectory().getAbsolutePath()+"/Android/data/"+databaseName);
    this.databaseFile = new File(this.databasePath);
    if (!this.databaseFile.exists())
        try {
            deployDataBase(DBHelper.databaseName, this.databasePath);
            return;
        } catch (IOException localIOException) {
            localIOException.printStackTrace();
        }
}

private void deployDataBase(String dbNAme, String dbPath)
        throws IOException {
    InputStream localInputStream = this.mContext.getAssets().open(dbNAme);
    FileOutputStream localFileOutputStream = new FileOutputStream(dbPath);
    byte[] arrayOfByte = new byte[1024];
    while (true) {
        int i = localInputStream.read(arrayOfByte);
        if (i <= 0) {
            localFileOutputStream.flush();
            localFileOutputStream.close();
            localInputStream.close();
            return;
        }
        localFileOutputStream.write(arrayOfByte, 0, i);
    }
}

@Override
public synchronized void close() {

    if (database != null)
        database.close();

    super.close();

}
@Override
public void onCreate(SQLiteDatabase db) {
    // TODO Auto-generated method stub

}

@Override  
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {  
 // TODO Auto-generated method stub 

} 


public List<String> getAllColleges(){
    List<String> colleges = new ArrayList<String>();

    // Select All Query
    String selectQuery = "SELECT * FROM colleges_list";

    SQLiteDatabase db = this.getReadableDatabase();
    Cursor cursor = db.rawQuery(selectQuery, null);

    // looping through all rows and adding to list
    if (cursor.moveToFirst()) {
        do {
            colleges.add(cursor.getString(1));
        } while (cursor.moveToNext());
    }

    // closing connection
    cursor.close();
    db.close();

    // returning colleges
    return colleges;
}

LogCat用于模拟器以外的设备： -

08-20 18:14:43.359: E/AndroidRuntime(24460): FATAL EXCEPTION: main
08-20 18:14:43.359: E/AndroidRuntime(24460): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.sqlite/com.crm.Quote_Details}: android.database.sqlite.SQLiteException: no such table: colleges_list: , while compiling: SELECT * FROM colleges_list
08-20 18:14:43.359: E/AndroidRuntime(24460):    at dalvik.system.NativeStart.main(Native Method)
08-20 18:14:43.359: E/AndroidRuntime(24460): Caused by: android.database.sqlite.SQLiteException: no such table: colleges_list: , while compiling: SELECT * FROM colleges_list
08-20 18:14:43.359: E/AndroidRuntime(24460):    at android.database.sqlite.SQLiteCompiledSql.native_compile(Native Method)
08-20 18:14:43.359: E/AndroidRuntime(24460):    at com.crm.DBHelper.getAllColleges(DBHelper.java:93)

我还注意到一件事，模拟器中复制的db具有rwxrwx---权限，而在任何设备中复制的db都有---rwxr-x权限。

如何摆脱这个问题？

Answer 1

使用SQLiteAssetHelper类来处理数据库。它可以帮助您使用数据库而不会弄乱文件权限。

可以找到它的jar文件here。下载＆amp;将其导入您的项目。

public class DBHelper extends SQLiteAssetHelper {

    private static final String DATABASE_NAME = "Db1.sqlite";
    private static final int DATABASE_VERSION = 1;

    public AssetsHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }


    public List<String> getAllColleges(){
        List<String> colleges = new ArrayList<String>();

        // Select All Query
        String selectQuery = "SELECT * FROM colleges_list ORDER BY Organization_Name";

        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.rawQuery(selectQuery, null);

        // looping through all rows and adding to list
        if (cursor.moveToFirst()) {
            do {
                colleges.add(cursor.getString(1));
            } while (cursor.moveToNext());
        }

        // closing connection
        cursor.close();
        db.close();

        // returning colleges
        return colleges;
    }

Answer 2

您是否正在更改数据库的结构？

如果您有更改，通常我会在运行新版本之前卸载该应用程序。运行新应用程序不会删除数据库，但卸载却会删除。您也可以使用adb命令'adb uninstall yourpackagename'

希望这会有所帮助。

无法在android中读取复制的数据库

2 个答案: