java - 如何在android中将数据库文件附加到apk文件

Question

我有一个数据库，其中大约有 6 个表。我想在手机上部署我的应用程序。但是如果我创建一个 apk 文件并将其加载到手机上，我如何将数据库文件附加到它？请帮助

编辑:我按照在 Assets 文件夹中加载数据库的过程，并更改 sqliteopenhelper 类，但应用程序仍然在手机上关闭

下面是我的 sqliteopenhelper

public class openingclass extends SQLiteOpenHelper
    {
        public openingclass(Context c) {
            super(c,Db_NAME, null, DB_VERSION);
        }
         public void createDataBase() {

                boolean dbExist;
                try {

                     dbExist = checkDataBase();


                } catch (SQLiteException e) {

                    e.printStackTrace();
                    throw new Error("database dose not exist");

                }

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

                    try {

                        copyDataBase();


                    } catch (IOException e) {

                        e.printStackTrace();
                        throw new Error("Error copying database");

                    }
            //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();


            }

            }

            /**
              * 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.
                throw new Error("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{



                    //copyDataBase();
                    //Open your local db as the input stream
                    InputStream myInput = c1.getAssets().open(Db_NAME);

                    // Path to the just created empty db
                    String outFileName = DB_PATH +"/"+ Db_NAME;
                    File databaseFile = new File( DB_PATH);
                     // check if databases folder exists, if not create one and its subfolders
                    if (!databaseFile.exists()){
                        databaseFile.mkdir();
                    }

                    //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();



            }



            @Override
            public synchronized void close() {

                if(myDataBase != null)
                myDataBase.close();

                super.close();

            }

        @Override
        public void onCreate(SQLiteDatabase arg0) {
            String S = "create table " +
                    TABLE_NAME +
                    " (" +
                    TABLE_COL_MAIL + " text primary key," +
                    TABLE_COL_NAME + " text," +
                    TABLE_COL_PASS + " text," +
                    TABLE_COL_PHO + " text," +
                    TABLE_COL_ADD + " text," +
                    TABLE_COL_GEN + " text," +
                    TABLE_COL_DOB + " text" +
                    ");";
            arg0.execSQL(S);

            String S1 = "create table " +
                    SECOND_TABLE_NAME +
                    " (" +
                    TABLE_COL_USER + " text," +
                    TABLE_COL_PRODUCT + " text," +
                    TABLE_COL_QUANTITY + " integer" +
                    ");";
            arg0.execSQL(S1);




        }

        @Override
        public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {
            // TODO Auto-generated method stub

        }

    }

Answer 1

您可以在 assets/ 文件夹中包含一个文件。在 SQLiteOpenHelper onCreate() 方法中，您可以打开文件并从中读取内容，然后使用它来创建数据库。