設計模式-Composition(組合模式)

將物件當作一個元件，將很多元件組合成樹狀結構，有人也稱為部分整理模式(part-whole pattern)。

組合模式定義

單個物件與組合的物件都有一致性

組合模式使用情況

1. 有物件需要表達複數的狀況
   

組合模式UML圖

組合模式範例

我們建立員工資料，利用組合模式建立多筆的員工資料

    /**
     * name: Employee.java
     * description :  員工個人資料
     * Created by bryant on 2017/1/25.
     */
    public class Employee {

        public  Employee(String name, String dept, BigDecimal salary){
            this.name = name ;
            this.dept = dept ;
            this.salary = salary;
        }

        private String no;

        //員工姓名
        private String name ;
        //薪水
        private BigDecimal salary ;
        //部門
        private String dept ;

        //取得員工姓名
        public String getName() {
            return name;
        }
        //設定員工姓名
        public void setName(String name) {
            this.name = name;
        }
        //取得員工薪水
        public BigDecimal getSalary() {
            return salary;
        }

        //設定員工薪水
        public void setSalary(BigDecimal salary) {
            this.salary = salary;
        }

        //取得部門
        public String getDept() {
            return dept;
        }
        //設定部門
        public void setDept(String dept) {
            this.dept = dept;
        }

        public String getNo() {
            return no;
        }

        public void setNo(String no) {
            this.no = no;
        }

        @Override
        public int hashCode() {
            return Integer.valueOf(this.no);
        }

        @Override
        public String toString() {
            StringBuilder sb = new StringBuilder() ;
            sb.append("") ;
            sb.append(""+no+"") ;
            sb.append(""+name+"") ;
            sb.append(""+dept+"") ;
            sb.append(""+salary+"") ;
            sb.append(""+"\r\n") ;
            return sb.toString();
        }
    }

    /**
     * name: EmployeeComposite.java
     * description :  員工集合
     * Created by bryant on 2017/1/25.
     */
    public class EmployeeComposite {

        private List list = new ArrayList() ;

        public List getEmployees(){
            return list;
        }

        public void addEmployee(Employee employee){
            list.add(employee);
        }

        public void remove(Employee employee){
            list.remove(employee);
        }

        @Override
        public String toString() {
            StringBuilder sb = new StringBuilder() ;
            for (Employee e: list){
                sb.append(e.toString());
            }
            return sb.toString() ;
        }
    }

    /**
     * name: EmployeeCompositeDemo.java
     * description :  員工集合DEMO
     * Created by bryant on 2017/1/25.
     */
    public class EmployeeCompositeDemo {

        public  static  void main(String[] args){
            Employee worker01 = new Employee("Jacker", "Worker",new BigDecimal("31000")) ;
            Employee worker02= new Employee("Mary", "Worker",new BigDecimal("31000")) ;
            Employee manager = new Employee("Bob","Manager", new BigDecimal("51000")) ;

            EmployeeComposite employeeComposite = new EmployeeComposite() ;
            employeeComposite.addEmployee(worker01);
            employeeComposite.addEmployee(worker02);
            employeeComposite.addEmployee(manager);
            System.out.println(employeeComposite.toString());

        }

    }