享元模式的实例

it2025-02-14 8

好了，废话不多说，直接上代码，首先抽象一个场景：

公司的管理层和普通员工对员工的信息有不同的权限。管理层可以修改员工的个人信息，普员工只能查看不能修改，擅自修改系统会给出提示。员工的个人信息是可以共享的，但是起职能范围和操作权限可以被管理层修改。

抽象享元角色：

[java] public interface IFlyWeight { /** * 判断传入的安全实体和权限，是否和享元对象内部状态匹配 * 参数 securityEntity 和 permit 是外蕴对象 * @param securityEntity * @param permit * @return */ public boolean match(String securityEntity, String permit); }

具体享元角色：

[java] public class AuthorizationFlyweight implements IFlyWeight { /** * 内蕴对象，安全实体 */ private String mSecurityEntity; /** * 内蕴对象，权限 */ private String mPermit; public AuthorizationFlyweight(String state) { String str[] = state.split(","); this.mSecurityEntity = str[0]; this.mPermit = str[1]; } @Override public boolean match(String securityEntity, String permit) { if (mSecurityEntity.equals(securityEntity) && mPermit.equals(permit)) { return true; } return false; } }

享元工厂：

[java] public class FlyWeightFactory { private static FlyWeightFactory mFactory = new FlyWeightFactory(); private FlyWeightFactory() { } public static FlyWeightFactory getInstance() { return mFactory; } /** * 缓存多个人IFlyWeight 对象 */ private Map<String, IFlyWeight> flyMap = new HashMap<String, IFlyWeight>(); /** * 获取享元单元 * @param key * @return */ public IFlyWeight getFlyWeight(String key) { IFlyWeight fly = flyMap.get(key); if(fly==null){ fly = new AuthorizationFlyweight(key); flyMap.put(key, fly); } return fly; } }

员工信息的管理工具：

[java] public class SecurityManager { private static SecurityManager manager = new SecurityManager(); private SecurityManager() { } public static SecurityManager getInstance() { return manager; } /** * 存放登录人员的权限 */ private Map<String, Collection<IFlyWeight>> map = new HashMap<String, Collection<IFlyWeight>>(); public void logon(String user) { Collection<IFlyWeight> coll = queryByUser(user); map.put(user, coll); } /** * 从数据库中获取某人所有的权限 * * @param user * @return */ private Collection<IFlyWeight> queryByUser(String user) { Collection<IFlyWeight> coll = new ArrayList<IFlyWeight>(); for (String s : TestDB.coll) { String str[] = s.split(","); if (str[0].equals(user)) { IFlyWeight fly = FlyWeightFactory.getInstance().getFlyWeight( str[1] + "," + str[2]); coll.add(fly); } } return coll; } /** * 判断某个用户对某个安全实体是否有某种权限 * * @param user * 用户 * @param securityEntity * 安全实体 * @param permit * 权限 * @return */ public boolean hasPermit(String user, String securityEntity, String permit) { Collection<IFlyWeight> coll = map.get(user); if (coll == null || coll.size() == 0) { System.out.println(user + "没有登录或者没有该权限..."); return false; } for (IFlyWeight fly : coll) { if (fly.match(securityEntity, permit)) { return true; } } return false; } }

模拟一个数据库保存员工信息：

[java] public class TestDB { public static Collection<String> coll = new ArrayList<String>(); static { coll.add("张三,人员列表,查看"); coll.add("李四,人员列表,查看"); coll.add("李四,薪资列表,查看"); coll.add("李四,薪资列表,修改"); for (short i = 0; i < 3; i++) { coll.add("张三" + i + ",人员列表,查看"); } } }

具体的实现，本例子是基于android实现的，java只单独写一个Test类在main里面实现就行了：

[java] view plain copy SecurityManager manager = SecurityManager.getInstance(); manager.logon("张三"); manager.logon("李四"); boolean b1 = manager.hasPermit("张三", "薪资列表", "查看"); boolean b2 = manager.hasPermit("李四", "薪资列表", "查看"); boolean b3 = manager.hasPermit("张三", "人员列表", "查看"); System.out.println("b1 = "+b1); System.out.println("b2 = "+b2); System.out.println("b3 = "+b3);

运行效果：

从数据库中可以看出来，张三是人事的普通员工，只能查看公司在职人员，对员工的薪资无权限查看，b1返回false，b3返回true

李四是人事普通员工兼财务主管，可以修改查询员工薪资并且可以查看在职员工信息，b2返回true

如果

[java] boolean b4 = manager.hasPermit("王武", "人员列表", "查看");

因为“王武”这个人没有登录，所以提示信息是 “没有登录或者没有该权限...”

转载于:https://www.cnblogs.com/w-wfy/p/5354275.html