如何将外部 SqliteDatabase 连接到 Android 应用程序？

Question

here is my problem. I am creating my database of text in program called SqliteDbBrowser after that I want to put it into /assets/ folder in android and load it to the application.

All the tutorials assume that you don't have any database and you create it clean from application and then fill it.

I have already put data into my database and don't want to create new one.

Here is some guy's tutorial http://www.reigndesign.com/blog/using-your-own-sqlite-database-in-android-applications/ and it somehow work's but it's not perfect, is it any other way to solve this ? Using ony SQLiteOpenHelper not mixing stuff?

Answer 1

I don't see the problem. I used that same example and it worked. In my project I had to check and, eventually, load the missing tables on the internal DB.

The DB will not be erased, unless you state so.

Therefore adding new tables will not erase any pre-existing ones.

Anyway, you said 'it somehow work's but it's not perfect', what do you mean? It either copies the tables or it doesn't. Right?

Answer 2

您提供的链接的示例运行良好，但最佳实践是在您的 android 应用程序中构建您的数据库，这样您就可以将准备好的数据库 DLL 与数据一起导出为插入语句，将这些插入语句添加到文件中，让我们在您的raw 文件夹，在创建数据库后，您可以读取插入语句并执行它们以插入数据。

Answer 3

First Put your Created Database in your Asset Folder.

Add Below Java File to your Project

package com.app.ourforms.database;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.Vector;

import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;

public class DBConnect extends SQLiteOpenHelper {
    ArrayList<String> arraylistUrl;
    public int GetCursor;

    public DBConnect(Context context, String db_name) {
        super(context, db_name, null, 2);

        if (db != null && db.isOpen())
            close();

        this.myContext = context;
        DB_NAME = db_name;

        try {
            createDataBase();
            openDataBase();
        } catch (IOException e) {
            // System.out.println("Exception in creation of database : "+
            // e.getMessage());
            e.printStackTrace();
        }

    }

    public void createDataBase() throws IOException {
        // boolean dbExist = checkDataBase();

        boolean dbExist = databaseExist();

        if (dbExist) {
            // System.out.println("Database Exist");
        } else {
            this.getReadableDatabase();

            try {
                copyDatabase();
            } catch (IOException e) {
                throw new Error("Error copying database");
            }
        }
    }

    private void copyDatabase() throws IOException {
        InputStream input = myContext.getAssets().open(DB_NAME);
        String outputFileName = DB_PATH + DB_NAME;
        OutputStream output = new FileOutputStream(outputFileName);

        byte[] buffer = new byte[1024];
        int length;
        while ((length = input.read(buffer)) > 0) {
            output.write(buffer, 0, length);
        }

        // Close the streams
        output.flush();
        output.close();
        input.close();
        // System.out.println(DB_NAME + "Database Copied !");
    }

    @Override
    public void onCreate(SQLiteDatabase db) {

    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

    }

    public void openDataBase() throws SQLException {
        // Open the database
        String myPath = DB_PATH + DB_NAME;
        db = SQLiteDatabase.openDatabase(myPath, null,
                SQLiteDatabase.OPEN_READWRITE);
    }

    public boolean isOpen() {
        if (db != null)
            return db.isOpen();
        return false;
    }

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

    public boolean databaseExist() {
        File dbFile = new File(DB_PATH + DB_NAME);
        return dbFile.exists();
    }

    private boolean checkDataBase() {
        SQLiteDatabase checkDB = null;
        try {
            String myPath = DB_PATH + DB_NAME;
            // System.out.println("My Pathe is:- " + myPath);
            // System.out.println("Open");
            checkDB = SQLiteDatabase.openDatabase(myPath, null,
                    SQLiteDatabase.OPEN_READWRITE);
            // System.out.println("checkDB value:" + checkDB);
            // System.out.println("My Pathe is:- " + myPath);
        } catch (Exception e) {
            // database does't exist yet.
        }

        if (checkDB != null) {
            // System.out.println("Closed");
            checkDB.close();
            // System.out.println("My db is:- " + checkDB.isOpen());
        }

        return checkDB != null ? true : false;
    }

    public Cursor execCursorQuery(String sql) {
        Cursor cursor = null;
        try {
            cursor = db.rawQuery(sql, null);
            GetCursor = cursor.getCount();
            Log.i("Inside execCursorQuery try", sql);
        } catch (Exception e) {
            Log.i("Inside execCursorQuery exception", e.getMessage());
        }
        return cursor;
    }

    public void execNonQuery(String sql) {
        try {
            db.execSQL(sql);
            // Log.d("SQL", sql);
        } catch (Exception e) {
            // Log.e("Err", e.getMessage());
        } finally {
            // closeDb();
        }
    }

    // ****************** Declare all the global variable
    // ****************************//

    private Context myContext;
    public String DB_PATH = "data/data/com.app.ourforms/databases/"; // path
    // of
    // your
    // datbase
    public static String DB_NAME = "OurForms.sqlite";// your database
                                                        // name
    @SuppressWarnings("unused")
    private static String ASSETS_DB_FOLDER = "db";
    private SQLiteDatabase db;

    public Vector<ArrayList<String>> getQuestion(String Query) {
        Vector<ArrayList<String>> alldata = new Vector<ArrayList<String>>();
        ArrayList<String> Question = new ArrayList<String>();
        ArrayList<String> Option1 = new ArrayList<String>();
        ArrayList<String> Option2 = new ArrayList<String>();
        ArrayList<String> Option3 = new ArrayList<String>();
        ArrayList<String> Option4 = new ArrayList<String>();
        ArrayList<String> Option5 = new ArrayList<String>();
        ArrayList<String> correct = new ArrayList<String>();
        ArrayList<String> correctness = new ArrayList<String>();
        ArrayList<String> Description = new ArrayList<String>();

        Cursor alldata_ques = execCursorQuery(Query);

        // GetCursor = alldata_ques.getCount();

        if (alldata_ques != null) {
            Log.e("Cursor length", "" + alldata_ques.getCount());
            GetCursor = alldata_ques.getCount();
            if (alldata_ques.getCount() > 0)

                while (alldata_ques.moveToNext()) {
                    Question.add((alldata_ques.getString(alldata_ques
                            .getColumnIndex("Question"))));
                    Option1.add(alldata_ques.getString(alldata_ques
                            .getColumnIndex("A")));
                    Option2.add(alldata_ques.getString(alldata_ques
                            .getColumnIndex("B")));
                    Option3.add(alldata_ques.getString(alldata_ques
                            .getColumnIndex("C")));
                    Option4.add(alldata_ques.getString(alldata_ques
                            .getColumnIndex("D")));
                    Option5.add(alldata_ques.getString(alldata_ques
                            .getColumnIndex("E")));
                    correct.add(alldata_ques.getString(alldata_ques
                            .getColumnIndex("Answer")));
                    correctness.add(alldata_ques.getString(alldata_ques
                            .getColumnIndex("Correctness")));
                    Description.add(alldata_ques.getString(alldata_ques
                            .getColumnIndex("Description")));
                }
            alldata.add(Question);
            alldata.add(Option1);
            alldata.add(Option2);
            alldata.add(Option3);
            alldata.add(Option4);
            alldata.add(Option5);
            alldata.add(correct);
            alldata.add(correctness);
            alldata.add(Description);
            // Log.d("VECTORSIZE", String.valueOf(alldata.size()));
        }

        return alldata;
    }

    public Vector<ArrayList<String>> getQuestions(String Query) {
        Vector<ArrayList<String>> alldata = new Vector<ArrayList<String>>();
        ArrayList<String> Question = new ArrayList<String>();
        ArrayList<String> Option1 = new ArrayList<String>();
        ArrayList<String> Option2 = new ArrayList<String>();
        ArrayList<String> Option3 = new ArrayList<String>();
        ArrayList<String> Option4 = new ArrayList<String>();
        ArrayList<String> Option5 = new ArrayList<String>();
        ArrayList<String> correct = new ArrayList<String>();
        ArrayList<String> Description = new ArrayList<String>();

        Cursor alldata_ques = execCursorQuery(Query);

        if (alldata_ques != null) {
            Log.e("Cursor length", "" + alldata_ques.getCount());
            if (alldata_ques.getCount() > 0)
                GetCursor = alldata_ques.getCount();
            while (alldata_ques.moveToNext()) {
                Question.add((alldata_ques.getString(alldata_ques
                        .getColumnIndex("Question"))));
                Option1.add(alldata_ques.getString(alldata_ques
                        .getColumnIndex("A")));
                Option2.add(alldata_ques.getString(alldata_ques
                        .getColumnIndex("B")));
                Option3.add(alldata_ques.getString(alldata_ques
                        .getColumnIndex("C")));
                Option4.add(alldata_ques.getString(alldata_ques
                        .getColumnIndex("D")));
                Option5.add(alldata_ques.getString(alldata_ques
                        .getColumnIndex("E")));
                correct.add(alldata_ques.getString(alldata_ques
                        .getColumnIndex("Answer")));
                Description.add(alldata_ques.getString(alldata_ques
                        .getColumnIndex("Description")));
            }
            alldata.add(Question);
            alldata.add(Option1);
            alldata.add(Option2);
            alldata.add(Option3);
            alldata.add(Option4);
            alldata.add(Option5);
            alldata.add(correct);
            alldata.add(Description);
            // Log.d("VECTORSIZE", String.valueOf(alldata.size()));
        }

        return alldata;
    }
}

In Above Code Change below line as per your project:

 public String DB_PATH = "data/data/YOUR_PACKAGE_NAME/databases/"; // path of your datbase

 public static String DB_NAME = "OurForms.sqlite";// your database Name

Inside your Activity Write Below Code For First Time Copy your Database to Application.

// For Database Copy
        myPrefs = getSharedPreferences("myPrefs", 0);

        // sharedPreferences = PreferenceManager
        // .getDefaultSharedPreferences(getApplicationContext());

        Data.FIRST_TIME_LAUNCH = myPrefs.getBoolean("FIRST_TIME_LAUNCH", true);

        if (Data.FIRST_TIME_LAUNCH) {

            Log.i(TAG, "FIRST TIME*************************");
            dbConnect = new DBConnect(getApplicationContext(),
                    "OurForms.sqlite");
            SharedPreferences.Editor editor = myPrefs.edit();
            editor.putBoolean("FIRST_TIME_LAUNCH", false);
            editor.commit();
        }

Hope it will help you.

Answer 4

public void getDataBaseData() {
        // /PawnStorescopy.db
        if (!new File("/data/data/" + this.getPackageName()
                + "/PawnStorescopy.sqlite").exists()) {
            try {
                FileOutputStream out = new FileOutputStream("data/data/"
                        + this.getPackageName() + "DatabaseName.sqlite");
                InputStream in = getAssets().open("DatabaseName.db");
                byte[] buffer = new byte[1024];
                int readBytes = 0;

                while ((readBytes = in.read(buffer)) != -1)
                    out.write(buffer, 0, readBytes);

                in.close();
                // out.close();
            } catch (IOException e) {
            }
        }

        SQLiteDatabase sqliteDB = SQLiteDatabase.openOrCreateDatabase( 
                "/data/data/" + this.getPackageName()
                        + "/DatabaseName.sqlite", null);

        Cursor cursor = sqliteDB.rawQuery("SELECT * FROM TableName", null);

        if (cursor.moveToFirst()) {
            do {
                ////Get Data
            } while (cursor.moveToNext());


            imageFilter(listDatabase);
        }

    }

Answer 5

Follow this link: https://github.com/jgilfelt/android-sqlite-asset-helper

Then,

1. Add your yourSqliteDb.db to folder in assets/databases. Create the folders if not present. assets/databases/yourSqliteDb.db How to create asset folder: http://code2care.org/2015/create-assets-folder-in-android-studio/

2. Create SQLiteAssetHelper Class as:

    public class MyDatabaseHelper extends SQLiteAssetHelper { private static final String DATABASE_NAME = "yourSqliteDb.db"; private static final int DATABASE_VERSION = 1; public MyDatabase(Context mContext) { super(mContext, DATABASE_NAME, null, DATABASE_VERSION ); } public Cursor getItems() { SQLiteDatabase db = getReadableDatabase(); Cursor c = db.rawQuery("Select * from items", null); //items is a column name in your table in database c.moveToFirst(); return c; }

   }

3. Now in MainActivity or wherever you need to read data from database,

    MyDatabaseHelper myDbHelper = new MyDatabaseHelper(this); SQLiteDatabase db = myDbHelper.ReadableDatabase(); String items = getResult(1); //number value from database table public String getResult(int id) { String name = null; try { Cursor c = null; c = db.rawQuery("select item from items where _id="+id, null); c.moveToFirst(); name = c.getString(c.getColumnIndex("item")); c.close(); } catch(Exception e) { e.printStackTrace(); } return name; }