设计模式——组合模式
组合模式:本质就是把不该是继承关系的类,改成树形结构,有树根节点,树中间节点和叶节点。
比如例子:
关系 学校 -> 学院 -> 专业
他们之间并非是继承关系,而是包含关系,或者说是组合关系。
随时有可能移除学院、增加学院、移除专业、增加专业;所以继承就不够灵活。
先创建一个共同的父类(此处接口也可以,甚至更好)
public abstract class OrganizationComponent {
private String name;//名字
private String des;//说明
//构造器
public OrganizationComponent(String name, String des) {
this.name = name;
this.des = des;
}
protected void add(OrganizationComponent organizationComponent){
//默认实现
new UnsupportedOperationException();
}
protected void remove(OrganizationComponent organizationComponent){
//默认实现
new UnsupportedOperationException();
}
//方法print,做成抽象的,子类都需要实现
protected abstract void print();
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getDes() {
return des;
}
public void setDes(String des) {
this.des = des;
}
}
然后创建学校类
public class University extends OrganizationComponent {
List<OrganizationComponent> organizationComponentLists = new ArrayList<>();
//构造器
public University(String name, String des) {
super(name, des);
}
@Override
protected void add(OrganizationComponent organizationComponent) {
super.add(organizationComponent);
organizationComponentLists.add(organizationComponent);
}
@Override
protected void remove(OrganizationComponent organizationComponent) {
super.remove(organizationComponent);
organizationComponentLists.remove(organizationComponent);
}
@Override
protected void print() {
System.out.println("--------------" + getName() + "--------------");
//遍历 organizationComponentLists
for (OrganizationComponent organizationComponent : organizationComponentLists) {
organizationComponent.print(); }
}
}
创建学院类
public class College extends OrganizationComponent {
List<OrganizationComponent> organizationComponentLists = new ArrayList<>();
//构造器
public College(String name, String des) {
super(name, des);
}
@Override
protected void add(OrganizationComponent organizationComponent) {
super.add(organizationComponent);
organizationComponentLists.add(organizationComponent);
}
@Override
protected void remove(OrganizationComponent organizationComponent) {
super.remove(organizationComponent);
organizationComponentLists.remove(organizationComponent);
}
@Override
protected void print() {
System.out.println("--------------" + getName() + "--------------");
//遍历 organizationComponentLists
for (OrganizationComponent organizationComponent : organizationComponentLists) {
organizationComponent.print(); }
}
}
创建专业类
public class Department extends OrganizationComponent {
public Department(String name, String des) {
super(name, des);
}
@Override
protected void print() {
System.out.println(getName());
}
}
用法:
public static void main(String[] args) {
//从大到小创建对象 学校
OrganizationComponent university = new University("清华大学", " 中国顶级大学 ");
//创建 学院
OrganizationComponent computerCollege = new College("计算机学院", " 计算机学院 ");
OrganizationComponent infoEngineercollege = new College("信息工程学院", " 信息工程学院 ");
//创建各个学院下面的系(专业)
computerCollege.add(new Department("软件工程", " 软件工程不错 "));
computerCollege.add(new Department("网络工程", " 网络工程不错 "));
computerCollege.add(new Department("计算机科学与技术", " 计算机科学与技术是老牌的专业 "));
//
infoEngineercollege.add(new Department("通信工程", " 通信工程不好学 "));
infoEngineercollege.add(new Department("信息工程", " 信息工程好学 "));
//将学院加入到 学校
university.add(computerCollege);
university.add(infoEngineercollege);
// university.print();
computerCollege.print();
}
}