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定义:组合模式(Compasite Pattern)也称为整体-部分(Part-Whole)模式,它的宗旨是通过将单个对象(叶子节点)和组合对象(树枝节点)用相同的接口进行表示

作用:使客户端对单个对象和组合对象保持一致的方式处理

属于结构型模式

适用场景

1.希望客户端可以忽略组合对象与单个对象的差异时；

2.对象层次具备整体和部分,呈树形结构(如树形菜单,操作系统目录结构,公司组织架构)

优点

1.清楚地定义分层次的复杂对象,表示对象的全部或部分层次

2.让客户端忽略了层次的差异,方便对整个层次结构进行控制

3.简化客户端代码

4.符合开闭原则

缺点

1.限制类型时会较为复杂

2.使设计变得更加抽象

例子

透明模式

public abstract class CourseComponent {
       public void addChild(CourseComponent component){
           throw new UnsupportedOperationException("不支持添加操作");    }    public void removeChild(CourseComponent component){
           throw new UnsupportedOperationException("不支持删除操作");    }    public String getName(CourseComponent component){
           throw new UnsupportedOperationException("不支持获取名称操作");    }    public double getPrice(CourseComponent component){
           throw new UnsupportedOperationException("不支持获取价格操作");    }    public void print(){
           throw new UnsupportedOperationException("不支持打印操作");    }}

public class CoursePage extends CourseComponent{
       private List
   
     itmes = new ArrayList<>();    private String name;    private Integer level;    public CoursePage(String name, Integer level) {
           this.name = name;        this.level = level;    }    @Override    public void addChild(CourseComponent component) {
           itmes.add(component);    }    @Override    public void removeChild(CourseComponent component) {
           itmes.remove(component);    }    @Override    public String getName(CourseComponent component) {
           return this.name;    }    @Override    public void print() {
           System.out.println(this.name);        for(CourseComponent component1 : itmes){
               if(this.level != null){
                   for(int i = 0; i < this.level; i ++){
                       System.out.print("   ");                }                for(int i = 0 ; i < this.level; i ++){
                       if(i == 0){
                           System.out.print("+");                    }                    System.out.print("-");                }            }            component1.print();        }    }}
   

public class Course extends CourseComponent{
       private String name;    private double price;    public Course(String name, double price) {
           this.name = name;        this.price = price;    }    @Override    public String getName(CourseComponent component) {
           return this.name;    }    @Override    public double getPrice(CourseComponent component) {
           return this.price;    }    @Override    public void print() {
          System.out.println(name + ",价格: " + price + "元");    }}

public class Test {
       public static void main(String[] args) {
           System.out.println("======透明的组合模式==========");        CourseComponent javaBase = new Course("Java入门课程",6300);        CourseComponent ai = new Course("人工智能",5000);        CourseComponent packageCourse = new CoursePage("Java架构师课程",2);        CourseComponent design = new Course("Java设计模式",1500);        CourseComponent source = new Course("源码分析",3000);        CourseComponent softSkill = new Course("软技能",3000);        packageCourse.addChild(design);        packageCourse.addChild(source);        packageCourse.addChild(softSkill);        CourseComponent catalog = new CoursePage("my课程目录",1);        catalog.addChild(javaBase);        catalog.addChild(ai);        catalog.addChild(packageCourse);        catalog.print();    }}

安全模式

public abstract class Directory {
       protected String name;    public Directory(String name){
           this.name = name;    }    public abstract void show();}

public class File extends Directory{
       public File(String name) {
           super(name);    }    @Override    public void show() {
           System.out.println(this.name);    }}

public class Folder extends Directory{
       private List
   
     dirs ;    private Integer level;    public Folder(String name,Integer level) {
           super(name);        this.level = level;        this.dirs = new ArrayList<>();    }    @Override    public void show() {
           System.out.println(this.name);        for(Directory directory : dirs){
               if(this.level != null){
                   for(int i = 0; i < this.level; i ++){
                       System.out.print("   ");                }                for(int i = 0 ; i < this.level; i ++){
                       if(i == 0){
                           System.out.print("+");                    }                    System.out.print("-");                }            }            directory.show();        }    }    public boolean add(Directory dir){
           return this.dirs.add(dir);    }    public boolean remove(Directory dir){
           return this.dirs.remove(dir);    }    public Directory get(int index){
           return this.dirs.get(index);    }    public void list(){
           for(Directory dir : dirs){
               System.out.println(dir.name);        }    }}
   

public class Test {
       public static void main(String[] args) {
           System.out.println("==========安全模式写法=========");        File qq = new File("qq.exe");        File wx = new File("微信.exe");        Folder office = new Folder("办公软件",2);        File word = new File("Word.exe");        File ppt = new File("PowerPoint.exe");        File excel = new File("Excel.exe");        office.add(word);        office.add(ppt);        office.add(excel);        Folder root = new Folder("/opt/",1);        root.add(qq);        root.add(wx);        root.add(office);        System.out.println("=======show()========");        root.show();        System.out.println("======list()===========");        root.list();    }}

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