java - 为 Dictionary 应用程序创建数据库

Question

我开始学习开发一个android应用程序。我想在android中开发一个母语词典。我的问题是如何创建一个可以存储词汇（文本）、音频（发音）以及图片的数据库？提前致谢。

Answer 1

为避免内存问题，您可以将音频和图像文件存储在 SD 卡中，并将文件的名称保存在数据库中。当您需要这些文件时，只需从数据库中获取详细信息并从 SD 卡中播放/显示。据我所知，这是最好的方法。

Answer 2

普通的 SQLite 数据库足以让您的应用程序存储音频、图片等内容。请注意，如果您要创建原生应用程序，最好使用 SD 卡存储图像和音频文件，这样您就可以根据需要检索文件。

Answer 3

SQLite 将是一个合理的解决方案。

如果您需要连接到网络数据库，我建议在托管 MySQL 数据库的服务器上使用 PHP 脚本。

以下是 SQLite 数据库外观的一些示例代码：

public class DatabaseHandler extends SQLiteOpenHelper {

    // All Static variables
    // Database Version
    private static final int DATABASE_VERSION = 1;

    // Database Name
    private static final String DATABASE_NAME = "android_api";

    // Login table name
    private static final String TABLE_LOGIN = "login";

    // Login Table Columns names
    private static final String KEY_ID = "id";
    private static final String KEY_NAME = "name";
    public static final String KEY_EMAIL = "email";
    private static final String KEY_UID = "uid";
    private static final String KEY_CREATED_AT = "created_at";

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

    // Creating Tables
    @Override
    public void onCreate(SQLiteDatabase db) {
        String CREATE_LOGIN_TABLE = "CREATE TABLE " + TABLE_LOGIN + "("
                + KEY_ID + " INTEGER PRIMARY KEY,"
                + KEY_NAME + " TEXT,"
                + KEY_EMAIL + " TEXT UNIQUE,"
                + KEY_UID + " TEXT,"
                + KEY_CREATED_AT + " TEXT" + ")";
        db.execSQL(CREATE_LOGIN_TABLE);
    }

    // Upgrading database
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // Drop older table if existed
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_LOGIN);

        // Create tables again
        onCreate(db);
    }

    /**
     * Storing user details in database
     * */
    public void addUser(String name, String email, String uid, String created_at) {
        SQLiteDatabase db = this.getWritableDatabase();

        ContentValues values = new ContentValues();
        values.put(KEY_NAME, name); // Name
        values.put(KEY_EMAIL, email); // Email
        values.put(KEY_UID, uid); // Email
        values.put(KEY_CREATED_AT, created_at); // Created At

        // Inserting Row
        db.insert(TABLE_LOGIN, null, values);
        db.close(); // Closing database connection
    }

    public void addUser(String email) {
        SQLiteDatabase db = this.getWritableDatabase();

        ContentValues values = new ContentValues();
        values.put(KEY_EMAIL, email); // Email

        // Inserting Row
        db.insert(TABLE_LOGIN, null, values);
        db.close(); // Closing database connection
    }

    public String getUser() {
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues values = new ContentValues();

        String user = values.getAsString(KEY_EMAIL);
        Log.v("DBH", user);
        db.close();
        return user;        
    }

    /**
     * Getting user data from database
     * */
    public HashMap<String, String> getUserDetails(){
        HashMap<String,String> user = new HashMap<String,String>();
        String selectQuery = "SELECT  * FROM " + TABLE_LOGIN;

        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.rawQuery(selectQuery, null);
        // Move to first row
        cursor.moveToFirst();
        if(cursor.getCount() > 0){
            user.put("name", cursor.getString(1));
            user.put("email", cursor.getString(2));
            user.put("uid", cursor.getString(3));
            user.put("created_at", cursor.getString(4));
        }
        cursor.close();
        db.close();
        // return user
        return user;
    }

    /**
     * Getting user login status
     * return true if rows are there in table
     * */
    public int getRowCount() {
        String countQuery = "SELECT  * FROM " + TABLE_LOGIN;
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.rawQuery(countQuery, null);
        int rowCount = cursor.getCount();
        db.close();
        cursor.close();

        // return row count
        return rowCount;
    }

    public String returnRows() {
        String response = "";
        String countQuery = "SELECT * FROM " + TABLE_LOGIN;
        SQLiteDatabase db = this.getReadableDatabase();
        for (int j = 0; j < getRowCount(); j++) {
            Cursor cursor = db.rawQuery(countQuery, null);
            response += cursor.getColumnName(j);
        }
        Log.v("LT", response);
        return response;
    }

    /**
     * Re crate database
     * Delete all tables and create them again
     * */
    public void resetTables(){
        SQLiteDatabase db = this.getWritableDatabase();
        // Delete All Rows
        db.delete(TABLE_LOGIN, null, null);
        db.close();
    }