安卓：从资源文件夹复制数据库（SQLite）出错

Question

安卓：从资源文件夹复制数据库（SQLite）出错

androidandroid-sqlite

3

我已经在SQLlite浏览器中设计了数据库。现在我正在尝试将它复制到我的根路径。

面临的问题：

复制数据库时出错。

链接：我正在使用这个例子寻求帮助。添加外部Sqllite Db到应用程序的链接我的DBhelper类：

package com.example.demo;

public class DBHelper extends SQLiteOpenHelper{


    //The Android's default system path of your application database.
    private static String DB_PATH = "/data/data/com.example.demo/databases/";

    private static String DB_NAME = "assesmenttool";

    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 DBHelper(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.
 }

我的主活动类

package com.example.demo;

import java.io.IOException;



public class MainActivity extends Activity {
    String Question_ID,Title,TitleDescription,QuestionText,QuestionTemplate,QuestionImage;
    DBHelper dbhelper;  
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


          dbhelper = new DBHelper(this);

            try {

                dbhelper.createDataBase();

        } catch (IOException ioe) {

            throw new Error("Unable to create database");

        }

        try {

            dbhelper.openDataBase();

        }catch(SQLException sqle){

            throw sqle;

        }



    }






}

我的LogCat

07-15 05:24:09.171: E/SQLiteLog(19825): (14) cannot open file at line 30191 of [00bb9c9ce4]
07-15 05:24:09.171: E/SQLiteLog(19825): (14) os_unix.c:30191: (2) open(/data/data/com.example.demo/databases/assesmenttool) - 
07-15 05:24:09.191: E/SQLiteDatabase(19825): Failed to open database '/data/data/com.example.demo/databases/assesmenttool'.
07-15 05:24:09.191: E/SQLiteDatabase(19825): android.database.sqlite.SQLiteCantOpenDatabaseException: unknown error (code 14): Could not open database
07-15 05:24:09.191: E/SQLiteDatabase(19825):    at android.database.sqlite.SQLiteConnection.nativeOpen(Native Method)
07-15 05:24:09.191: E/SQLiteDatabase(19825):    at android.database.sqlite.SQLiteConnection.open(SQLiteConnection.java:209)
07-15 05:24:09.191: E/SQLiteDatabase(19825):    at android.database.sqlite.SQLiteConnection.open(SQLiteConnection.java:193)
07-15 05:24:09.191: E/SQLiteDatabase(19825):    at android.database.sqlite.SQLiteConnectionPool.openConnectionLocked(SQLiteConnectionPool.java:463)
07-15 05:24:09.191: E/SQLiteDatabase(19825):    at android.database.sqlite.SQLiteConnectionPool.open(SQLiteConnectionPool.java:185)
07-15 05:24:09.191: E/SQLiteDatabase(19825):    at android.database.sqlite.SQLiteConnectionPool.open(SQLiteConnectionPool.java:177)
07-15 05:24:09.191: E/SQLiteDatabase(19825):    at android.database.sqlite.SQLiteDatabase.openInner(SQLiteDatabase.java:804)
07-15 05:24:09.191: E/SQLiteDatabase(19825):    at android.database.sqlite.SQLiteDatabase.open(SQLiteDatabase.java:789)
07-15 05:24:09.191: E/SQLiteDatabase(19825):    at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:694)
07-15 05:24:09.191: E/SQLiteDatabase(19825):    at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:669)
07-15 05:24:09.191: E/SQLiteDatabase(19825):    at com.example.demo.DBHelper.checkDataBase(DBHelper.java:76)
07-15 05:24:09.191: E/SQLiteDatabase(19825):    at com.example.demo.DBHelper.createDataBase(DBHelper.java:43)
07-15 05:24:09.191: E/SQLiteDatabase(19825):    at com.example.demo.MainActivity.onCreate(MainActivity.java:27)
07-15 05:24:09.191: E/SQLiteDatabase(19825):    at android.app.Activity.performCreate(Activity.java:5231)
07-15 05:24:09.191: E/SQLiteDatabase(19825):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
07-15 05:24:09.191: E/SQLiteDatabase(19825):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
07-15 05:24:09.191: E/SQLiteDatabase(19825):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
07-15 05:24:09.191: E/SQLiteDatabase(19825):    at android.app.ActivityThread.access$800(ActivityThread.java:135)
07-15 05:24:09.191: E/SQLiteDatabase(19825):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
07-15 05:24:09.191: E/SQLiteDatabase(19825):    at android.os.Handler.dispatchMessage(Handler.java:102)
07-15 05:24:09.191: E/SQLiteDatabase(19825):    at android.os.Looper.loop(Looper.java:136)
07-15 05:24:09.191: E/SQLiteDatabase(19825):    at android.app.ActivityThread.main(ActivityThread.java:5017)
07-15 05:24:09.191: E/SQLiteDatabase(19825):    at java.lang.reflect.Method.invokeNative(Native Method)
07-15 05:24:09.191: E/SQLiteDatabase(19825):    at java.lang.reflect.Method.invoke(Method.java:515)
07-15 05:24:09.191: E/SQLiteDatabase(19825):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
07-15 05:24:09.191: E/SQLiteDatabase(19825):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
07-15 05:24:09.191: E/SQLiteDatabase(19825):    at dalvik.system.NativeStart.main(Native Method)
07-15 05:24:09.481: E/AndroidRuntime(19825): FATAL EXCEPTION: main
07-15 05:24:09.481: E/AndroidRuntime(19825): Process: com.example.demo, PID: 19825
07-15 05:24:09.481: E/AndroidRuntime(19825): java.lang.Error: Error copying database
07-15 05:24:09.481: E/AndroidRuntime(19825):    at com.example.demo.DBHelper.createDataBase(DBHelper.java:59)
07-15 05:24:09.481: E/AndroidRuntime(19825):    at com.example.demo.MainActivity.onCreate(MainActivity.java:27)
07-15 05:24:09.481: E/AndroidRuntime(19825):    at android.app.Activity.performCreate(Activity.java:5231)
07-15 05:24:09.481: E/AndroidRuntime(19825):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
07-15 05:24:09.481: E/AndroidRuntime(19825):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
07-15 05:24:09.481: E/AndroidRuntime(19825):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
07-15 05:24:09.481: E/AndroidRuntime(19825):    at android.app.ActivityThread.access$800(ActivityThread.java:135)
07-15 05:24:09.481: E/AndroidRuntime(19825):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
07-15 05:24:09.481: E/AndroidRuntime(19825):    at android.os.Handler.dispatchMessage(Handler.java:102)
07-15 05:24:09.481: E/AndroidRuntime(19825):    at android.os.Looper.loop(Looper.java:136)
07-15 05:24:09.481: E/AndroidRuntime(19825):    at android.app.ActivityThread.main(ActivityThread.java:5017)
07-15 05:24:09.481: E/AndroidRuntime(19825):    at java.lang.reflect.Method.invokeNative(Native Method)
07-15 05:24:09.481: E/AndroidRuntime(19825):    at java.lang.reflect.Method.invoke(Method.java:515)
07-15 05:24:09.481: E/AndroidRuntime(19825):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
07-15 05:24:09.481: E/AndroidRuntime(19825):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
07-15 05:24:09.481: E/AndroidRuntime(19825):    at dalvik.system.NativeStart.main(Native Method)

- Tushar Narang

请检查我的代码：https://gist.github.com/bigdestroyer/ea6452ed19756d3b6233您可以像这样使用它：PrepopulatedHelper.from(context).loadPrepopulated("/data/data/com.your.project/databases/your_database.db"); - Héctor

3个回答

2

也许您的问题出在DB路径上，使用以下代码获取DBPATH，

if(android.os.Build.VERSION.SDK_INT >= 17){
               DB_PATH = context.getApplicationInfo().dataDir + "/databases/";
          }
else
      {
    DB_PATH = context.getResources().getString(R.string.database_path) + context.getPackageName() + "/databases/";
     }

编辑：

在string.xml文件中

<string name="database_path">/data/data/</string>

- Ranjithkumar

我正在尝试在4.4.2上运行它。 - Tushar Narang

0

请勿使用硬编码数据库路径。请使用以下代码获取数据库路径。

String DB_PATH = context.getDatabasePath(Constant.DATABASE_NAME).getPath();

- Amandeep Rohila

网页内容由stack overflow 提供, 点击上面的

可以查看英文原文，
原文链接

- user3690440 · Accepted Answer

只需要更改

这个

 private static String DB_NAME = "assesmenttool";

目标

 private static String DB_NAME = "assesmenttool.db";