我正在用sql开发一个简单的Android应用程序.
我按照以下指南 –
http://www.reigndesign.com/blog/using-your-own-sqlite-database-in-android-applications/

尝试打开数据库时出错.
这是我的DataBaseHelp.Java类 –

public class DataBaseHelper extends sqliteOpenHelper{
private static String DB_PATH = "/data/data/and.testDB/databases/";
private static String DB_NAME = "MyData";
private sqliteDatabase myDataBase; 
private final Context myContext;
public DataBaseHelper(Context context) {
 super(context,DB_NAME,null,1);
    this.myContext = context;
} 
public void createDataBase() throws IOException{
 boolean dbExist = checkDataBase();
 if(dbExist){
  //do nothing - database already exist
 }else{
     this.getReadableDatabase();
     try {
   copyDataBase();
  } catch (IOException e) {
      throw new Error("Error copying database");
     }
 }
}
private boolean checkDataBase(){
 sqliteDatabase checkDB = null;
 try{
  String myPath = DB_PATH + DB_NAME;
  checkDB = sqliteDatabase.openDatabase(myPath,sqliteDatabase.OPEN_READONLY);
 }catch(sqliteException e){
  //database does't exist yet.
 }
 if(checkDB != null){
  checkDB.close();
 }
 return checkDB != null ? true : false;
}
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,length);
 }
 //Close the streams
 myOutput.flush();
 myOutput.close();
 myInput.close();
}
public void openDataBase() {
 //Open the database
    String myPath = DB_PATH + DB_NAME;
 myDataBase = sqliteDatabase.openDatabase(myPath,sqliteDatabase.OPEN_READONLY);
}
@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) {
  }
}

这是我的testDB.Java类 –

public class testDB extends Activity {
sqliteDatabase myDataBase;
public String[] gur = new String[4];
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    DataBaseHelper myDbHelper = new DataBaseHelper(this);
    myDbHelper = new DataBaseHelper(this);
    try {
        myDbHelper.createDataBase();
} catch (IOException ioe) {
    throw new Error("Unable to create database");
}
try {
    myDbHelper.openDataBase();
// Here is the problem-Can't open the database/
}catch(sqlException sqle){
    throw sqle;
}
    myDataBase = myDbHelper.getWritableDatabase();
    Cursor c = myDataBase.rawQuery("SELECT * FROM beer",null);
if (c != null ) {
    if  (c.moveToFirst()) {
          for(int x=0;x< 1;x++)
          {
              gur[x] = (c.getString(c.getColumnIndex("name")));
              c.moveToNext();
          }
}
    Toast.makeText(this,gur[0],Toast.LENGTH_LONG).show();
}
        }
    }

我使用sqlite数据库浏览器创建了数据库,创建了一个名为“beer”的表,添加了2行并将其放在我项目的/ assests文件夹中.

请注意,我是sql的新手,也是我第一次使用它.我整天都在寻找答案而找不到答案.

谢谢！