Android：錯誤打開數據庫

Question

我從資產文件夾中獲取此數據庫，但無法在我的活動中打開它。 我的數據庫存儲在資產文件夾和MIO_DATABASE.db：

Database.java：

package it.mi.action.app; 

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 Database extends SQLiteOpenHelper{ 

//The Android's default system path of your application database. 
private static final String DB_PATH = "/data/data/it.mi.action.app/databases/"; 
private static final String DB_NAME = "MIO_DATABASE.db"; 
private SQLiteDatabase myDataBase; 
private final Context myContext; 

public Database(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{ 

     //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. 

} 

我的活動（mia.java）：

package it.mi.action.app; 

    import java.io.IOException; 
    import android.app.Activity; 
    import android.database.SQLException; 
    import android.os.Bundle; 

    public class mia extends Activity{ 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.mia); 
     final Database info=new Database(this); 
     try { 
      info.createDataBase(); 
     } catch (IOException ioe) { 
      throw new Error("Unable to create database"); 
     } 
     try { 
      info.openDataBase(); 
     }catch(SQLException sqle){ 
      throw sqle; 
     } 
    } 
} 

該應用的工作原理，但在LogCat我看到這個錯誤：

08-01 09:37:32.772: E/Database(1774): sqlite3_open_v2("/data/data/it.mi.action.app/databases/MIO_DATABASE.db", &handle, 1, NULL) failed 

什麼問題？

Answer 1

這個錯誤發生在您第一次運行該項目，因爲它創建了sqlite數據庫。檢查此鏈接，這是由@大衛Using your own SQLite database in Android apps

問他有同樣的錯誤你這樣一個問題：sqlite3_open_v2(「/data/data/com.testapp/databases/database.db

我也有同樣的問題。但隨後@David說： I just realized the issue is not the loading of the database it is actually the first time it is read.

Answer 2

你應該檢查你的數據庫是否存在於指定的路徑中。有關更多信息，請參閱here。

另外，儘量保存您的數據庫在內部或外部存儲器，因爲你只有在應用程序的文件夾asset讀取權限。有關更多信息，請參閱here。