writeObject与readObject的使用例子

写了一段程序，这段程序是用来：
传入1个用户id以及数据data，
然后在网站的cache目录下生成${employee_id}.ser的文件，把data写进去。
如果该文件存在，则删掉再重新创建下。

    public static ArrayList<HashMap<String, String>> getQueryData(String employee_id) {
        String dataFile = webPath + "cache/" + employee_id + ".ser";
        System.out.println(dataFile);
        ArrayList<HashMap<String, String>> result = new ArrayList<HashMap<String,String>>();
        try {
            ObjectInputStream in = new ObjectInputStream(new FileInputStream(dataFile));
            result = (ArrayList<HashMap<String, String>>) in.readObject();
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return result;
    }
    
    public static void writeQueryData(String employee_id, ArrayList<HashMap<String, String>> data) {
        String dataFile = webPath + "cache/" + employee_id + ".ser";
        try {
            File f = new File(dataFile);
            System.out.println(f.getAbsolutePath());
            if (f.exists()) {
                f.delete();
                f.createNewFile();
            }
            System.out.println(f.getAbsolutePath());
            ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream(f));
            out.writeObject(data);
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }