java design pattern - Proxy pattern

Proxy Pattern 说白了就是用一个object 去控制另外一个object的access. 

Usage in JDK:
java.lang.reflect.Proxy.
java.rmi.*(whole package)

看代码比看理论舒服多了.

package proxy;

interface IFolder{
    public void performOperations();
}

class Folder implements IFolder{

    @Override
    public void performOperations(){
        //access folder and perform various operations like copy or cut files
        System.out.println("Performing operations on folder");
    }
}

class User{
    String user;
    String pass;

    public User(String user, String pass){
        super();
        this.user = user;
        this.pass = pass;
    }

    public String getUser(){
        return user;
    }

    public void setUser(String user){
        this.user = user;
    }

    public String getPass(){
        return pass;
    }

    public void setPass(String pass){
        this.pass = pass;
    }
}


class FolderProxy implements IFolder{
    Folder folder ;
    User user;

    public FolderProxy(User user){
        this.user = user;
    }

    @Override
    public void performOperations(){
        if(user.getUser() .equalsIgnoreCase("dev") &&
            user.getPass().equalsIgnoreCase("abc-123")){
            folder = new Folder();
            folder.performOperations();
        }else{
            System.out.println("You do't not have access to this folder");
        }
    }
}


public class ProxyPatternDemo {
    public static void main(String[] args){
        User user = new User("dev","abc-123");
        FolderProxy fp = new FolderProxy(user);
        System.out.println("when user and pass are correct");
        fp.performOperations();
        System.out.println("*******************************");
        //if we get wrong user and pass
        User wronguser = new User("abc","wrong");
        FolderProxy fp2 = new FolderProxy(wronguser);
        System.out.println("when user and pass are incorrect");
        fp2.performOperations();
    }
}