📜  在 android 中将 Sqlite 数据库导出为 csv - 任何代码示例

📅  最后修改于: 2022-03-11 14:55:39.549000             🧑  作者: Mango

代码示例1
public boolean exportDatabase() {
        DateFormat df = DateFormat.getDateInstance(DateFormat.SHORT, Locale.getDefault());

        /**First of all we check if the external storage of the device is available for writing.
         * Remember that the external storage is not necessarily the sd card. Very often it is
         * the device storage.
         */
        String state = Environment.getExternalStorageState();
        if (!Environment.MEDIA_MOUNTED.equals(state)) {
            return false;
        }
        else {
            //We use the Download directory for saving our .csv file.
            File exportDir = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS);
            if (!exportDir.exists())
            {
                exportDir.mkdirs();
            }

            File file;
            PrintWriter printWriter = null;
            try
            {
                file = new File(exportDir, "MyCSVFile.csv");
                file.createNewFile();
                printWriter = new PrintWriter(new FileWriter(file));

                /**This is our database connector class that reads the data from the database.
                 * The code of this class is omitted for brevity.
                 */
                SQLiteDatabase db = this.getReadableDatabase(); //open the database for reading

                /**Let's read the first table of the database.
                 * getFirstTable() is a method in our DBCOurDatabaseConnector class which retrieves a Cursor
                 * containing all records of the table (all fields).
                 * The code of this class is omitted for brevity.
                 */
                Cursor curCSV = db.rawQuery("select * from contacts", null);
                //Write the name of the table and the name of the columns (comma separated values) in the .csv file.
                printWriter.println("FIRST TABLE OF THE DATABASE");
                printWriter.println("DATE,ITEM,AMOUNT,CURRENCY");
                while(curCSV.moveToNext())
                {
                    Long date = curCSV.getLong(curCSV.getColumnIndex("date"));
                    String title = curCSV.getString(curCSV.getColumnIndex("title"));
                    Float amount = curCSV.getFloat(curCSV.getColumnIndex("amount"));
                    String description = curCSV.getString(curCSV.getColumnIndex("description"));

                    /**Create the line to write in the .csv file.
                     * We need a String where values are comma separated.
                     * The field date (Long) is formatted in a readable text. The amount field
                     * is converted into String.
                     */
                    String record = df.format(new Date(date)) + "," + title + "," + amount + "," + description;
                    printWriter.println(record); //write the record in the .csv file
                }

                curCSV.close();
                db.close();
            }

            catch(Exception exc) {
                //if there are any exceptions, return false
                return false;
            }
            finally {
                if(printWriter != null) printWriter.close();
            }

            //If there are no errors, return true.
            return true;
        }
    }
}