深入浅出组合模式
1 概念
基本概念:组合模式是结构型设计模式的一种,用来表示“整体-部分”的关系,使用户对单个对象和组合对象具有一致的访问性。
主要解决:将整体的各个部分都一视同仁,共同进行处理或操作,具有一致的行为,使得操作者与复杂的部分元素解耦合。
2 应用场景
- 树形菜单
- 目录、文件管理
- 部门-员工管理
- 整体与部分的场景
- …
3 代码实现
【场景说明】公司的工资结算系统需要计算出每位员工和每个部门的工资,使用组合模式实现一个程序,能够分别计算出每位员工的薪资和每个部门的工资总和
【类的设计】
【具体代码】
/**
* @desc: 员工和部门共同部分(薪资)的抽象
* @author: YanMingXin
* @create: 2021/9/25-21:31
**/
public abstract class SalaryTools {
public Integer id;
public Double salary;
public abstract Double getThisSalary();
public SalaryTools(Integer id) {
this.id = id;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public Double getSalary() {
return salary;
}
public void setSalary(Double salary) {
this.salary = salary;
}
}
/**
* @desc: 部门类
* @author: YanMingXin
* @create: 2021/9/25-21:33
**/
public class Department extends SalaryTools {
private List<SalaryTools> list = new ArrayList<>();
public Department(Integer id) {
super(id);
}
@Override
public Double getThisSalary() {
double sum = 0;
for (SalaryTools obj : list) {
sum += obj.getThisSalary();
}
this.salary = sum;
return salary;
}
public void addDepartOrEmployee(SalaryTools obj) {
this.list.add(obj);
}
public List<SalaryTools> getList() {
return list;
}
}
/**
* @desc: 员工类
* @author: YanMingXin
* @create: 2021/9/25-21:32
**/
public class Employee extends SalaryTools {
public Employee(Integer id, Double salary) {
super(id);
this.salary = salary;
}
@Override
public Double getThisSalary() {
return salary;
}
}
/**
* @desc: 测试类
* @author: YanMingXin
* @create: 2021/9/25-21:29
**/
public class MyComposite {
public static void main(String[] args) {
Department department = new Department(1001);
Department dep1 = new Department(10011);
Employee e1 = new Employee(10011, 10000D);
Employee e2 = new Employee(100111, 10000D);
Employee e3 = new Employee(100112, 10000D);
department.addDepartOrEmployee(e1);
dep1.addDepartOrEmployee(e2);
dep1.addDepartOrEmployee(e3);
department.addDepartOrEmployee(dep1);
//System.out.println("001部门总工资:" + department.getThisSalary());
//System.out.println("0011部门总工资:" + dep1.getThisSalary());
List<SalaryTools> list = department.getList();
for (SalaryTools salaryTools : list) {
if (salaryTools instanceof Department) {
System.out.println("部门" + salaryTools.getId() + ":" + salaryTools.getThisSalary());
List<SalaryTools> list1 = ((Department) salaryTools).getList();
for (SalaryTools salaryTools1 : list1) {
System.out.println("员工" + salaryTools1.getId() + ":" + salaryTools1.getThisSalary());
}
} else {
System.out.println("员工" + salaryTools.getId() + ":" + salaryTools.getThisSalary());
}
}
}
}