程序中不应对邮箱地址进行硬编码，可以使用配置文件或数据库存储的方式来存储系统所需的数据；并且录入数据时，还可以在对敏感数据做加密处理之后再进行数据的录入。

    1. public class UserDAO {
    2.     private static Map<Integer, User> users = new LinkedHashMap<Integer, User>();
    4.     static {
    5.         users.put(1001, new User(1001, "韩信", 22, EncryptUtil.encrypt(phoneDAO.getPhoneById(1001)), EncryptUtil.encrypt(emailDAO.getEmailById(1001))));
    6.         users.put(1002, new User(1002, "张良", 30, EncryptUtil.encrypt(phoneDAO.getPhoneById(1002)), EncryptUtil.encrypt(emailDAO.getEmailById(1002))));
    7.         users.put(1003, new User(1003, "萧何", 27, EncryptUtil.encrypt(phoneDAO.getPhoneById(1003)), EncryptUtil.encrypt(emailDAO.getEmailById(1003))));
    8.         // ...
    9.     }
    11.     // 用户信息的增删改查方法
    12.     // ...
    13. }
    14. public class User {
    15.     private int id;
    16.     private String name;
    17.     private int age;
    18.     private String tel;
    19.     private String email;
    21.     public User() {}
    23.     public User(int id, String name, int age, String tel, String email) {
    24.         this.id = id;
    25.         this.name = name;
    26.         this.age = age;
    27.         this.tel = tel;
    28.         this.email = email;
    29.     }
    31.     // Getter and Setter
    32.     // ...
    33. }