【結構型模式】組合模式

前言（一些廢話，可以忽略）

• 組合模式，是我們依賴關係中的一種，在這裏又變換成爲一種設計模式，那麼它的核心肯定也是將類與類通過組合的方式拼湊在一起了
• PS.部分類實現見文末

要解決的問題

• 我們都知道一個單位，有組織架構，一個學校有各個不同的院系，一個院系又有不同的部門，那麼我們式樣哪種方式來方便擴展的，符合代碼設計原則的方式來組織這種層級架構關係呢
• 這就是組合模式，通過將一個不同層級的組織機構一層一層的關聯，既方便了擴展，又十分清晰的捋順了各個方面的線條

組合模式

• 以學校來舉例，學校下面有院系，院系下面有部門，但是這三種層級結構都是組織，所以我們創建父類或接口
• 可以向頂級組織學校中添加院系，可以向院系中添加部門，及刪改查等

/**
 * @program: ade-someproblem
 * @author: cade franklin
 * @create: 2019-12-29 29:11
 **/
public interface OrganizationComponent {
    void add(OrganizationComponent department);
    void print();
    void remove(OrganizationComponent department);
}

• 學校，是一個組織，實現OrganizationComponent，在它中間包含院系的List，將其組合進來
• 另外院系和部門的組織相似

/**
 * @program: ade-someproblem
 * @author: cade franklin
 * @create: 2019-12-29 29:11
 **/
public class University implements OrganizationComponent {

    private String name;

    private List<College> collegeList = new ArrayList();

    public University(String name) {
        this.name = name;
    }

    @Override
    public void add(OrganizationComponent organizationComponent) {
        if(organizationComponent instanceof College){
            College college = (College)organizationComponent;
            collegeList.add(college);
        }
    }

    @Override
    public void print() {
        System.out.println("======University.print:"+name);

        for (int i = 0; i < collegeList.size(); i++) {
            OrganizationComponent college = collegeList.get(i);
            college.print();
        }
    }

    @Override
    public void remove(OrganizationComponent organizationComponent) {
        if(organizationComponent instanceof College){
            College college = (College)organizationComponent;
            collegeList.remove(college);
        }
    }
}

• 我們的使用如下

/**
 * @program: ade-someproblem
 * @author: cade franklin
 * @create: 2019-12-29 29:11
 **/
public class ComponsiteMode {
    public static void main(String[] args) {

        OrganizationComponent department = new Department("團委");
        OrganizationComponent department1 = new Department("院辦");
        OrganizationComponent department2 = new Department("教研室");

        OrganizationComponent college = new College("計算機學院");
        college.add(department);
        college.add(department1);
        college.add(department2);

        OrganizationComponent college1 = new College("電子信息學院");

        OrganizationComponent university = new University("XXX大學");
        university.add(college);
        university.add(college1);

//	需要打印學校就直接從學校開始調用
//        university.print();
//	如果需要從下一層級遍歷，直接使用下一層級，非常的靈活
        college.print();

    }
}

總結

• 組合模式是通過組合的方式，將下一層級的組織結構組合在類中，這樣能夠靈活的使用

附錄代碼

/**
 * @program: ade-someproblem
 * @author: cade franklin
 * @create: 2019-12-29 29:11
 **/
public class Department implements OrganizationComponent {

    private String name;

    public Department(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public void add(OrganizationComponent department) {
        throw new UnsupportedOperationException("Department.add");
    }

    @Override
    public void print() {
        System.out.println("Department.print:"+name);
    }

    @Override
    public void remove(OrganizationComponent department) {
        throw new UnsupportedOperationException("Department.remove");
    }

}
/**
 * @program: ade-someproblem
 * @author: cade franklin
 * @create: 2019-12-29 29:11
 **/
public class College implements OrganizationComponent {

    private String name;

    private List<Department> departmentList = new ArrayList();

    public College(String name) {
        this.name = name;
    }

    @Override
    public void add(OrganizationComponent organizationComponent) {
        if(organizationComponent instanceof Department){
            Department department = (Department)organizationComponent;
            departmentList.add(department);
        }

    }

    @Override
    public void print() {
        System.out.println("------College.print:"+name);
        for (int i = 0; i < departmentList.size(); i++) {
            OrganizationComponent department = departmentList.get(i);
            department.print();
        }
    }

    @Override
    public void remove(OrganizationComponent organizationComponent) {
        if(organizationComponent instanceof Department){
            Department department = (Department)organizationComponent;
            departmentList.remove(department);
        }
    }
}

願你不捨愛與自由。