java - SQLite异常: No such table even if there is table

Question

尝试从 SQLite 数据库获取值时出现此错误:-

07-15 02:49:33.040: E/SQLiteLog(1770): (1) no such table: collegelist
07-15 02:49:33.040: D/AndroidRuntime(1770): Shutting down VM
07-15 02:49:33.050: W/dalvikvm(1770): threadid=1: thread exiting with uncaught exception (group=0xb2acaba8)
07-15 02:49:33.050: E/AndroidRuntime(1770): FATAL EXCEPTION: main
07-15 02:49:33.050: E/AndroidRuntime(1770): Process: com.existingsqlitedatabase, PID: 1770
07-15 02:49:33.050: E/AndroidRuntime(1770): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.existingsqlitedatabase/com.existingsqlitedatabase.MainActivity}: android.database.sqlite.SQLiteException: no such table: collegelist (code 1): , while compiling: SELECT * FROM collegelist
07-15 02:49:33.050: E/AndroidRuntime(1770):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
07-15 02:49:33.050: E/AndroidRuntime(1770):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
07-15 02:49:33.050: E/AndroidRuntime(1770):     at android.app.ActivityThread.access$800(ActivityThread.java:135)
07-15 02:49:33.050: E/AndroidRuntime(1770):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
07-15 02:49:33.050: E/AndroidRuntime(1770):     at android.os.Handler.dispatchMessage(Handler.java:102)

我已经检查了我的数据库(大学)中的表(大学列表)，它在那里，但我不知道为什么它不读取它。我还在这里检查了一些与之相关的早期帖子，但它们没有帮助。

这是我的 DatabaseHelper 类:-

public class DataBaseHelper extends SQLiteOpenHelper 
{ 
private static String TAG = "DataBaseHelper"; // Tag just for the LogCat window 
//destination path (location) of our database on device 
private static String DB_PATH = "";  
private static String DB_NAME ="colleges";// Database name 
private SQLiteDatabase mDataBase;  
private final Context mContext; 

public DataBaseHelper(Context context)  
{ 
super(context, DB_NAME, null, 1);// 1? its Database Version 
DB_PATH = context.getApplicationInfo().dataDir + "/databases/"; 
this.mContext = context; 
}    

public void createDataBase() throws IOException 
{ 
//If database not exists copy it from the assets 

boolean mDataBaseExist = checkDataBase(); 
if(!mDataBaseExist) 
{ 
    this.getReadableDatabase(); 
    this.close(); 
    try  
    { 
        //Copy the database from assests 
        copyDataBase(); 
        Log.e(TAG, "createDatabase database created"); 
    }  
    catch (IOException mIOException)  
    { 
        throw new Error("ErrorCopyingDataBase"); 
    } 
  } 
} 
//Check that the database exists here: /data/data/your package/databases/Da Name 
private boolean checkDataBase() 
{ 
    File dbFile = new File(DB_PATH + DB_NAME); 
    //Log.v("dbFile", dbFile + "   "+ dbFile.exists()); 
    return dbFile.exists(); 
} 

//Copy the database from assets 
private void copyDataBase() throws IOException 
{ 
    InputStream mInput = mContext.getAssets().open(DB_NAME); 
    String outFileName = DB_PATH + DB_NAME; 
    OutputStream mOutput = new FileOutputStream(outFileName); 
    byte[] mBuffer = new byte[1024]; 
    int mLength; 
    while ((mLength = mInput.read(mBuffer))>0) 
    { 
        mOutput.write(mBuffer, 0, mLength); 
    } 
    mOutput.flush(); 
    mOutput.close(); 
    mInput.close(); 
} 

//Open the database, so we can query it 
public boolean openDataBase() throws SQLException 
{ 
    String mPath = DB_PATH + DB_NAME; 
    //Log.v("mPath", mPath); 
    mDataBase = SQLiteDatabase.openDatabase(mPath, null, SQLiteDatabase.CREATE_IF_NECESSARY); 
    //mDataBase = SQLiteDatabase.openDatabase(mPath, null, SQLiteDatabase.NO_LOCALIZED_COLLATORS); 
    return mDataBase != null; 
} 

@Override 
public synchronized void close()  
{ 
    if(mDataBase != null) 
        mDataBase.close(); 
    super.close(); 
}

@Override
public void onCreate(SQLiteDatabase arg0) {
    // TODO Auto-generated method stub

}

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

} 

 /**
 * Getting all labels
 * returns list of labels
 * */
public List<String> getAllLabels(){
    List<String> labels = new ArrayList<String>();

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

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

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

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

    // returning lables
    return labels;
   }
} 

请帮忙。

Answer 1

Load databaese from asset folder

public class DataHelper extends SQLiteOpenHelper {

public SQLiteDatabase database = null;
public File databaseFile;
public static String databaseName = "myDb";
public String databasePath = "";
Context mContext;

public DataHelper(Context paramContext) {

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


    this.databasePath = ("data/data/" + paramContext.getPackageName()+"/databases/"+databaseName);
    //this.databasePath = ("data/data/" + paramContext.getPackageName() + "/data.sqlite");
    this.databaseFile = new File(this.databasePath);
    if (!this.databaseFile.exists())
        try {
            deployDataBase(DataHelper.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

}

}