src/com/util/FileEveryDaySerialNumber.java

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package com.util;

import java.io.File;
import java.util.Date;
import java.util.List;

public class FileEveryDaySerialNumber extends EveryDaySerialNumber{

		/**
		 * 持久化存储的文件
		 */
		private File file = null;

		/**
		 * 存储的分隔符
		 */
		private final static String FIELD_SEPARATOR = ",";

		public FileEveryDaySerialNumber(int width, String filename) {
			super(width);
			file = new File(filename);
		}

		@Override
		protected int getOrUpdateNumber(Date current, int start) {
			String date = format(current);
			int num = start;
			if (file.exists()) {
				List<String> list = FileUtil.readList(file);
				String[] data = list.get(0).split(FIELD_SEPARATOR);
				if (date.equals(data[0])) {
					num = Integer.parseInt(data[1]);
				}
			}
			FileUtil.rewrite(file, date + FIELD_SEPARATOR + (num + 1));
			return num;
		}
}