学步园

//写入文件
File file = new File(sessionNumFileName);
        FileWriter writer = null;
        try {
            //创建输出流
            writer = new FileWriter(file);
            //将SessionNum写入文件
            writer.write(String.valueOf(sessionNum));
        } catch (IOException e) {
            //若写入失败，则记录日志，并返回
            logger.dead("DSCTRL1009W", e, sessionNumFileName);
            throw new SystemException(e);
        } finally {
            try {
                if (writer != null) {
                    //关闭输出流
                    writer.flush();
                    writer.close();
                }
            } catch (IOException e) {
                logger.dead("DSCTRL1009W", e, sessionNumFileName);
                throw new SystemException(e);
            }
        }
        return true;

读取文件

File file = new File(fileName);
        //若指定文件不存在，则创建新文件，并记录日志
        if (!file.exists()) {
            try {
                file.createNewFile();
                logger.note("DSCTRL0092N", fileName);
            } catch (IOException e) {
                logger.dead("DSCTRL0093E", fileName);
                throw new SystemException("can not create SessionNumFile:["
                        + fileName + "]", e);
            }
        }

        BufferedReader reader = null;
        try {
            reader = new BufferedReader(new FileReader(file));
            String tempString = reader.readLine();
            ret = Integer.parseInt(tempString == null ? "" : tempString.trim());
        } catch (Exception e) {
            logger.note("DSCTRL0094N", fileName);
            logger.note("DSCTRL0002N", "SessionNum", "0");
            ret = 0;
        } finally {
            try {
                if (reader != null) {
                    reader.close();
                }
            } catch (IOException e1) {
                logger.note("DSCTRL0095N", e1, fileName);
            }
        }

        return ret;