委托模式

总述

主要是自己不想做的事交给被委托的对象去做。

类图

委托模式.png

实现

调用

package com.company;

public class Main {

    public static void main(String[] args) {
    // write your code here
        Employer employer = new Employer();
        employer.printSomething();
    }
}

效果

com.company.Employee

Process finished with exit code 0

委托者

package com.company;

public class Employer {

    private DelegateInterface contractObject;

    public DelegateInterface getContractObject() {
        if (this.contractObject == null)this.contractObject = new Employee();
        return contractObject;
    }

    public void printSomething() {
        System.out.println(this.getContractObject().exampleMethod());
    }
}

被委托者

package com.company;

public class Employee implements DelegateInterface {
    @Override
    public String exampleMethod() {
        return this.getClass().getName();
    }
}

双方的契约

package com.company;

public interface DelegateInterface {
    String exampleMethod();
}