微服务架构 云计算 重构 -改变既有代码的设计 ---- 笔记(10)

    class ClientClass {
        Person person = new Person()
        person.doSomething()
    }

    class Person{
        Department department = new Department()
        department.doSomething()
    }

解决方法

    class ClientClass{
        Server server = new Server()
        server.doSomething()
    }

    class Server{
        Delegate delegate = new Delegate()
        void doSomething(){
            delegate.doSomething()
        }
    }
    //委托类其实隐藏在客户类里面
    // 改变不会传播到客户端那边，因为它之后影响到服务端这边
    class Delegate{
        void doSomething(){...}
    }

动机

关键在于封装

类应该尽量的使用其他的类

> manager = john.getDepartment().getManager();

    class Person {
        Department _department;
        public Department getDepartment() {
            return _department;
        }
        public void setDepartment(Department arg) {
            _department = arg;
            }
        }

    class Department {
        private String _chargeCode;
        private Person _manager;
        public Department (Person manager) {
            _manager = manager;
        }
        public Person getManager() {
            return _manager;
        }
        ...

to

> manager = john.getManager();

    class Person {
        ...
        public Person getManager() {
            return _department.getManager();
        }
    }

一个类通过代理干了太多的事情

让客户直接调用委托

    class ClientClass {
        Person person = new Person()
        person.doSomething()
    }

    class Person{
        Department department = new Department()
        department.doSomething()
    }

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