试试这个：

private void ExportData() {
    
         //CHECK IF YOU HAVE WRITE PERMISSIONS OR RETURN
        int permission = ActivityCompat.checkSelfPermission(getActivity(), Manifest.permission.WRITE_EXTERNAL_STORAGE);
    
        if (permission != PackageManager.PERMISSION_GRANTED) {
            Toast.makeText(getContext(), "Storage permissions not granted", Toast.LENGTH_SHORT).show();
            return;
        }
    
        //get database object
        myDbhelper = new MyDbHelper(getContext());
        SQLiteDatabase database = myDbhelper.getWritableDatabase();
    
        //delete all entries in the second table
        database.delete("Table2",null,null);
    
        //Create a cursor of the main database with your filters and sort order applied
        Cursor cursor = getActivity().getContentResolver().query(
                uri,
                projections,
                selection,
                args,
                sortOrder);
    
        //loop through cursor and add entries from first table to second table
        try {
            while (cursor.moveToNext()) {
                final String ColumnOneIndex = cursor.getString(cursor.getColumnIndexOrThrow("COLUMN_ONE"));
                final String ColumnTwoIndex = cursor.getString(cursor.getColumnIndexOrThrow("COLUMN_TWO"));
                final String ColumnThreeIndex = cursor.getString(cursor.getColumnIndexOrThrow("COLUMN_THREE"));
    
          //add entries from table one into the table two
                ContentValues values = new ContentValues();
                values.put("TABLE2_COLUMN_1", ColumnOneIndex);
                values.put("TABLE2_COLUMN_2", ColumnTwoIndex );
                values.put("TABLE2_COLUMN_3", ColumnThreeIndex);
    
                database.insert("table2", null, values);
            }
        } finally {
            //close cursor after looping is complete
            cursor.close();
        }
    
         //create a string for where you want to save the excel file
        final String savePath = Environment.getExternalStorageDirectory() + "/excelfileTemp";
        File file = new File(savePath);
        if (!file.exists()) {
            file.mkdirs();
        }
         //create the sqLiteToExcel object
        SQLiteToExcel sqLiteToExcel = new SQLiteToExcel(getContext(), "databasefile.db",savePath);
    
        //use sqLiteToExcel object to create the excel file 
        sqLiteToExcel.exportSingleTable("table2","excelfilename.xls", new SQLiteToExcel.ExportListener() {
            @Override
            public void onStart() {
    
            }
            @Override
            public void onCompleted(String filePath) {
                //now attach the excel file created and be directed to email activity
                Uri newPath = Uri.parse("file://" + savePath + "/" +"excelfilename.xls");
    
                StrictMode.VmPolicy.Builder builder = new StrictMode.VmPolicy.Builder();
                StrictMode.setVmPolicy(builder.build());
    
                Intent emailintent = new Intent(Intent.ACTION_SEND);
    
                emailintent.setType("application/vnd.ms-excel");
                emailintent.putExtra(Intent.EXTRA_SUBJECT, "Subject");
                emailintent.putExtra(Intent.EXTRA_TEXT, "I'm email body.");
                emailintent.putExtra(Intent.EXTRA_STREAM,newPath);
    
                startActivity(Intent.createChooser(emailintent, "Send Email"));
            }
            @Override
            public void onError(Exception e) {
                System.out.println("Error msg: " + e);
                Toast.makeText(getContext(), "Failed to Export data", Toast.LENGTH_SHORT).show();
            }
        });
    }