设计模式

public class Client {
    public static void main (String[] args) {
        UserServiceImpl userService =new UserServiceImpl();

        UserServiceProxy proxy = new UserServiceProxy();
        proxy.setUserServiceImpl(userService);
        proxy.add();
        proxy.delete();
        proxy.upadte();
    }
}

1 public interface UserService {
2     public  void add();
3     public  void upadte();
4     public  void query();
5     public  void delete();
6 }

 1 public class UserServiceImpl implements UserService {
 2 
 3 
 4     public void add () {
 5         System.out.println("添加");
 6     }
 7 
 8     public void upadte () {
 9         System.out.println("更新");
10     }
11 
12     public void query () {
13         System.out.println("查询");
14     }
15 
16     public void delete () {
17         System.out.println("删除");
18     }
19 }

 1 public class UserServiceProxy implements  UserService
 2 {
 3     private UserServiceImpl userServiceImpl;
 4 
 5     public void setUserServiceImpl (UserServiceImpl userServiceImpl) {
 6         this.userServiceImpl = userServiceImpl;
 7     }
 8 
 9     public void add () {
10         log();
11         userServiceImpl.add();
12     }
13 
14     public void upadte () {
15         log();
16         userServiceImpl.upadte();
17     }
18 
19     public void query () {
20         log();
21         userServiceImpl.query();
22     }
23 
24     public void delete () {
25         log();
26         userServiceImpl.delete();
27     }
28     public void log(){
29         System.out.println("新加的业务，不能改变原有代码");
30     }
31 }