Question

这是我第一次开发Android应用程序。我正在尝试编写一个能够将csv文件导入android sqlite本地数据库的应用程序。这是我目前的设计：

当用户按下按钮时，将使用db.execSQL删除旧表（“DROP TABLE IF EXISTS”+ ......）
使用db.execSQL（CREATE TABLE TABLE1 ......）
读取csv文件的内容并将其分解为子字符串。
使用db.insert（TABLE1，null，contentValues）将子字符串插入csv文件;

我想问一下我是否应该尝试使用onUpgrade函数来替换我的步骤1,2。我在更新DATABASE_VERSION方面做了一些研究。如果我更新DATABASE_VERSION的值，将调用onUpgrade并且可以完成相同的功能。使用onUpgrade和我的编码有什么区别？哪一个更好？

P.S。请注意，此按钮每天会按一次。

这是我的编码：

主要活动

button_import_csv.setOnClickListener(new View.OnClickListener(){
        public void onClick(View v){


            DatabaseHelper helper = new DatabaseHelper(getApplicationContext());
            SQLiteDatabase db = helper.getWritableDatabase();
            db.execSQL("DROP TABLE IF EXISTS "+ TABLE_1);
            String CREATE_TB;

            CREATE_TB = "CREATE TABLE adv_sales_order ("
                    + "order_date text not null, "
                    + "cust_code text not null, "
                    + "customer_ref_no text, "
                    + "line_no integer not null, "
                    + "item_code text not null, "
                    + "tran_code text not null, "
                    + "order_qty real not null, "
                    + "constraint pk_adv_sales_order "
                    + "primary key (order_date, "
                    + "cust_code, "
                    + "item_code, "
                    + "tran_code))";
            db.execSQL(CREATE_TB);
            try{

                FileReader file = new FileReader("/sdcard/downloadedfolder/A1/adv_sales_order.csv");
                BufferedReader buffer = new BufferedReader(file);
                ContentValues contentValues=new ContentValues();
                String line = "";
                String tableName ="adv_sales_order";

                db.beginTransaction();
                while ((line = buffer.readLine()) != null) {
                    String[] str = line.split("\t");


                    contentValues.put("order_date", str[0]);
                    contentValues.put("cust_code", str[1]);
                    contentValues.put("customer_ref_no", str[2]);
                    contentValues.put("line_no", str[3]);
                    contentValues.put("item_code", str[4]);
                    contentValues.put("tran_code", str[5]);
                    contentValues.put("order_qty", str[6]);


                    db.insert(tableName, null, contentValues);

                }
                db.setTransactionSuccessful();
                db.endTransaction();
            }catch (IOException e){

            }

            helper.close();
        }
    });

DatabaseHelper

public void onCreate(SQLiteDatabase db) {
    // TODO Auto-generated method stub

    String CREATE_TB;

    CREATE_TB = "CREATE TABLE adv_sales_order ("
            + "order_date text not null, "
            + "cust_code text not null, "
            + "customer_ref_no text, "
            + "line_no integer not null, "
            + "item_code text not null, "
            + "tran_code text not null, "
            + "order_qty real not null, "
            + "constraint pk_adv_sales_order "
            + "primary key (order_date, "
            + "cust_code, "
            + "item_code, "
            + "tran_code))";
    db.execSQL(CREATE_TB);
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    // TODO Auto-generated method stub

    db.execSQL("DROP TABLE IF EXISTS "+ TABLE_1);
    onCreate(db);
}

public void insert_adv_sales_order (ContentValues values) {
    SQLiteDatabase db = getWritableDatabase();
    db.insert("adv_sales_order", null, values);
    db.close();
}

在android应用程序中使用onUpgrade

0 个答案: