Java 尝试将资产文件夹中的数据库复制到应用程序'；s数据库文件夹

我目前正在从事一个项目，但在尝试将资产文件夹中的数据库复制到应用程序的数据库文件夹时遇到了一些问题。现在我甚至无法将它复制到应用程序的文件夹中。然而，在我以前的一次尝试中，我设法将它复制到应用程序的数据库文件夹中，但发现它是一个空数据库。我似乎真的搞不懂这个。有什么建议吗

下面是用于复制数据库的代码：

package sirtat.individualProject.PublicTransportationTimeScheduler;

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import android.content.Context;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;

public class DataBaseHelper extends SQLiteOpenHelper{

    //The Android's default system path of your application database.
    private static String DB_PATH = "/data/data/sirtat.individualProject.PublicTransportationTimeScheduler/databases/";

    private static String DB_NAME = "transportdb";

    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 DataBaseHelper(Context context) {

     super(context, DB_NAME, null, 1);
        this.myContext = context;
    } 

  /**
     * 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
     }else{

      //By calling this method and empty database will be created into the default system path
               //of your application so we are gonna be able to overwrite that database with our database.
         this.getReadableDatabase();

         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(SQLiteException 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_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) {

 }

        // Add your public helper methods to access and get content from the database.
       // You could return cursors by doing "return myDataBase.query(....)" so it'd be easy
       // to you to create adapters for your views.

}

希望你们能帮我

/** *在系统上创建一个空数据库，并用您自己的数据库重写它。 **/

public void createDataBase() throws IOException{

 boolean dbExist = checkDataBase();

 if(dbExist){
  //do nothing - database already exist
 }else{

//您在这里已经提到，如果数据库内存中没有db，您将创建新的数据库 ***检查这里

  //By calling this method and empty database will be created into the default system path
           //of your application so we are gonna be able to overwrite that database with our database.

//阻止这一行，执行一次

//这是.getReadableDatabase（）

---

等待我应该阻止哪一个？我不明白你的意思@@@Ryuujin您需要阻止此行//this.getReadableDatabase（）；我试过那样做。。但是它仍然没有复制数据库。。在应用程序的数据库中仍然找不到任何内容。它实际上在模拟器上@@是的，所以一旦你的数据库在你的数据库文件夹中，它就不会再创建了。adb也要卸载sirtat.individualProject.PublicTransportationTimeScheduler

     try {

   copyDataBase();

  } catch (IOException e) {

      throw new Error("Error copying database");

     }
 }