无法使用Apache POI编写Excel文件

Question

I am using the following code to write data to an excel file:

    public class WriteExcellFile {

    public boolean saveExcelFile(Context context, String fileName) {

        // check if available and not read only
        if (!isExternalStorageAvailable() || isExternalStorageReadOnly()) {
            Log.d("FileUtils", "Storage not available or read only");
            return false;
        }

        boolean success = false;

        //New Workbook
        Workbook wb = new HSSFWorkbook();

        Cell c = null;

        //Cell style for header row
        CellStyle cs = wb.createCellStyle();
        cs.setFillForegroundColor(HSSFColor.LIME.index);
        cs.setFillPattern(HSSFCellStyle.SOLID_FOREGROUND);

        //New Sheet
        Sheet sheet1 = null;
        sheet1 = wb.createSheet("myOrder");

        // Generate column headings
        Row row = sheet1.createRow(0);

        c = row.createCell(0);
        c.setCellValue("Item Number");
        c.setCellStyle(cs);

        c = row.createCell(1);
        c.setCellValue("Quantity");
        c.setCellStyle(cs);

        c = row.createCell(2);
        c.setCellValue("Price");
        c.setCellStyle(cs);

        sheet1.setColumnWidth(0, (15 * 500));
        sheet1.setColumnWidth(1, (15 * 500));
        sheet1.setColumnWidth(2, (15 * 500));

        // Create a path where we will place our List of objects on external storage
        File file = new File(context.getExternalFilesDir(null), fileName);
        FileOutputStream os = null;

        try {
            os = new FileOutputStream(file);
            wb.write(os);
            Log.d("FileUtils", "Writing file" + file);
            success = true;
        } catch (IOException e) {
            Log.d("FileUtils", "Error writing " + file, e);
        } catch (Exception e) {
            Log.d("FileUtils", "Failed to save file", e);
        } finally {
            try {
                if (null != os)
                    os.close();
            } catch (Exception ex) {
            }
        }

        return success;
    }


    public static boolean isExternalStorageReadOnly() {
        String extStorageState = Environment.getExternalStorageState();
        if (Environment.MEDIA_MOUNTED_READ_ONLY.equals(extStorageState)) {
            return true;
        }
        return false;
    }

    public static boolean isExternalStorageAvailable() {
        String extStorageState = Environment.getExternalStorageState();
        if (Environment.MEDIA_MOUNTED.equals(extStorageState)) {
            return true;
        }
        return false;
    }
}

Code runs without any error on logcat, but when i go to the folder where it was supposed write the excel file, the folder is empty. I have also added permission in Android Manifest file.

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

Answer 1

File file = new File(context.getExternalFilesDir(null), fileName);

在上面一行中，如果用Environment.DIRECTORY_DOCUMENTS替换null，那么输出文件将存储在那里。