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私は現在、DATABASE_TABLE、DATABASE_TABLE2、DATABASE_TABLE3という名前の3つのデータベーステーブルで保存されたAndroidアセットフォルダーにデータベースを持っています。今のところ、「DATABASE_TABLE」に必要なすべてを実装しており、DATABASE_TABLE2とDATABASE_TABLE3のコードを繰り返さないようにしたいと思います。これを行うための最良のアプローチは何ですか?役立つ提案があれば幸いです。

package com.topscore.db;

import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.List;

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

import com.topscore.core.Question;

public class Database {
    String DB_PATH = "/data/data/com.topscore/databases/";
    private static final String DATABASE_NAME = "tsp";
    private static final int DATABASE_VERSION = 1;

    private final Context mContext;
    private DatabaseHelper DBHelper;
    private SQLiteDatabase db;
    private static final String DATABASE_TABLE = "CHEMISTRY";
        private static final String DATABASE_TABLE2 = "MATH";
        private static final String DATABASE_TABLE3 = "PHYSICS";
    public static final String KEY_ID = "QuestionId";
    public static final String KEY_TYEP = "ExamType";
    public static final String KEY_YEAR = "Year";
    public static final String KEY_SUBJECT = "Subject";
    public static final String KEY_QUESTION = "Question";
    public static final String KEY_ANSWERONE = "Answer1";
    public static final String KEY_ANSWERTWO = "Answer2";
    public static final String KEY_ANSWERTHREE = "Answer3";
    public static final String KEY_ANSWERFOUR = "Answer4";
    public static final String KEY_ANSWERFIVE = "Answer5";
    public static final String KEY_CURRECTANSWER = "CorrectAnswer";



    public Database(Context context) {
        mContext = context;
        DBHelper = new DatabaseHelper(mContext);
    }

    /*
     * Database helper class which fires events on database open/create/upgrade
     */

    private static class DatabaseHelper extends SQLiteOpenHelper {

        public DatabaseHelper(Context context) {
            super(context, DATABASE_NAME, null, DATABASE_VERSION);

        }

        @Override
        public void onCreate(SQLiteDatabase db) {
            // db.execSQL(DATABASE_CREATE_ITEMS);

        }

        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
            db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLE_TOPSCORE);

        }
    }

    public Database open() throws SQLException {
        db = DBHelper.getWritableDatabase();
        return this;
    }

    public void close() {
        DBHelper.close();
    }

    /*
     * Insert Dairy
     */
    public long insertDairy(long time, String note) {
        ContentValues initialValues = new ContentValues();
        initialValues.put(KEY_TYEP, note);
        initialValues.put(KEY_YEAR, time);
        initialValues.put(KEY_SUBJECT, System.currentTimeMillis());
        return db.insert(DATABASE_TABLE_TOPSCORE, null, initialValues);
    }

    /*
     * Update Dairy
     */
    public boolean UpdateDairy(long time, String note, int id) {
        ContentValues initialValues = new ContentValues();
        initialValues.put(KEY_TYEP, note);
        initialValues.put(KEY_YEAR, time);
        initialValues.put(KEY_SUBJECT, System.currentTimeMillis());
        return db.update(DATABASE_TABLE_TOPSCORE, initialValues, KEY_ID + "="
                + id, null) > 0;
    }

    /*
     * Returns all the dairys from the table memory
     */
    public List<Question> getAllDairys(String year, String type, String sub) {
        year = year.replaceAll("'", "''");
        type = type.replaceAll("'", "''");
        sub = sub.replaceAll("'", "''");
        List<Question> list = new ArrayList<Question>();
        Cursor _cursor = db.query(true, DATABASE_TABLE_TOPSCORE, null, KEY_YEAR
                + " = '" + year + "' AND " + KEY_TYEP + " = '" + type
                + "' AND " + KEY_SUBJECT + " = '" + sub + "'", null, null,
                null, KEY_ID +" ASC", null);
        if (_cursor != null) {
            _cursor.moveToFirst();
            int count = _cursor.getCount();
            Question question;
            List<String> optionslist;
            for (int i = 0; i < count; i++) {
                _cursor.moveToPosition(i);
                question = new Question();
                question.setId(_cursor.getInt(0));
                question.setType(_cursor.getString(1).trim());
                String pyear = _cursor.getString(2).trim();
                try {
                    question.setYear(Integer.parseInt(pyear));
                } catch (Exception e) {

                }
                question.setSubject(_cursor.getString(3).trim());
                question.setQuestion(_cursor.getString(4).trim());
                optionslist = new ArrayList<String>();
                optionslist.add(_cursor.getString(4).trim());
                if (_cursor.getString(5).trim().length() > 0) {
                    optionslist.add(_cursor.getString(5).trim());
                    if (_cursor.getString(5).trim().equals(
                            _cursor.getString(10).trim())) {
                        question.setCurretAnswer(1);

                    }
                }
                if (_cursor.getString(6).trim().length() > 0) {
                    optionslist.add(_cursor.getString(6).trim());
                    if (_cursor.getString(6).trim().equals(
                            _cursor.getString(10).trim())) {
                        question.setCurretAnswer(2);

                    }
                }
                if (_cursor.getString(7).trim().length() > 0) {
                    optionslist.add(_cursor.getString(7).trim());
                    if (_cursor.getString(7).trim().equals(
                            _cursor.getString(10).trim())) {
                        question.setCurretAnswer(3);

                    }
                }
                if (_cursor.getString(8).trim().length() > 0) {
                    optionslist.add(_cursor.getString(8).trim());
                    if (_cursor.getString(8).trim().equals(
                            _cursor.getString(10).trim())) {
                        question.setCurretAnswer(4);

                    }
                }
                if (_cursor.getString(9).trim().length() > 0) {
                    optionslist.add(_cursor.getString(9).trim());
                    if (_cursor.getString(9).trim().equals(
                            _cursor.getString(10).trim())) {
                        question.setCurretAnswer(5);

                    }
                }
                question.setChoiceList(optionslist);
                list.add(question);

            }
        }
        return list;
    }

    /*
     * Returns dairy from the table memory
     */
    public Question getDairyWithId(int id) {
        Question dairy = new Question();
        Cursor _cursor = db.query(true, DATABASE_TABLE_TOPSCORE, null, KEY_ID
                + "=" + id, null, null, null, null, null);
        if (_cursor != null) {
            dairy = new Question();
            _cursor.moveToFirst();

        }
        return dairy;
    }

    /*
     * Returns dairy from the table memory
     */
    public String[] getAllSubjects(int id) {
        String string[] = null;
        String key = "";
        if (id == 3) {
            key = KEY_SUBJECT;
        } else if (id == 1) {
            key = KEY_TYEP;
        } else if (id == 2) {
            key = KEY_YEAR;
        }

        Cursor _cursor = db.query(true, DATABASE_TABLE_TOPSCORE, null, null,
                null, key, null, null, null);
        if (_cursor != null && _cursor.getCount() > 0) {

            _cursor.moveToFirst();
            int count = _cursor.getCount();
            string = new String[count];
            for (int i = 0; i < count; i++) {
                string[i] = _cursor.getString(id);
            }

        }
        return string;
    }

    public boolean deleteDairy(int id) {
        return db.delete(DATABASE_TABLE_TOPSCORE, KEY_ID + "=" + id, null) > 0;
    }

    /**
     * Creates a empty database on the system and rewrites it with your own
     * database.
     * */
    public void createDataBase() {

        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.
            DBHelper.getReadableDatabase();

            try {

                copyDataBase();

            } catch (Exception 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 + DATABASE_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() {
        try {

            // Open your local db as the input stream
            InputStream myInput = mContext.getAssets().open("TopScoreDB");

            // Path to the just created empty db
            String outFileName = DB_PATH + DATABASE_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();
        } catch (Exception e) {

        }

    }
}
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1 に答える 1

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私はこれについて@Dave Newtonと一緒です-3つのテーブルが構造的にすべて同じである場合、なぜそれらが3つあるのですか?

物理学、化学、数学などを参照する「SubjectType」のような既存のテーブルにフィールドを追加してみませんか?

次に、そのフィールドを使用して、質問を並べ替えて引き出すことができますか?

于 2016-07-11T00:39:27.467 に答える