23种设计模式(八)组合模式

心已赠人 2022-12-30 08:02 173阅读 0赞

## 组合模式 ##

树形结构，组合对象，单个对象，符合开闭原则，可以增加叶子节点  
根据课程举例子：  
课程与目录类组合 叶子节点

public abstract class CatalogComponent { 
        public void add(CatalogComponent catalogComponent){ 
            throw new UnsupportedOperationException("不支持添加操作");
        }
    
        public void remove(CatalogComponent catalogComponent){ 
            throw new UnsupportedOperationException("不支持删除操作");
        }
    
    
        public String getName(CatalogComponent catalogComponent){ 
            throw new UnsupportedOperationException("不支持获取名称操作");
        }
    
    
        public double getPrice(CatalogComponent catalogComponent){ 
            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");
        }
    }

课程类

public class Course extends CatalogComponent { 
        private String name;
        private double price;
    
        public Course(String name, double price) { 
            this.name = name;
            this.price = price;
        }
    
        @Override
        public String getName(CatalogComponent catalogComponent) { 
            return this.name;
        }
    
        @Override
        public double getPrice(CatalogComponent catalogComponent) { 
            return this.price;
        }
    
        @Override
        public void print() { 
            System.out.println("Course Name:"+name+" Price:"+price);
        }
    
    }

public class CourseCatalog extends CatalogComponent { 
        private List<CatalogComponent> items = new ArrayList<CatalogComponent>();
        private String name;
        private Integer level;
    
    
        public CourseCatalog(String name,Integer level) { 
            this.name = name;
            this.level = level;
        }
    
        @Override
        public void add(CatalogComponent catalogComponent) { 
            items.add(catalogComponent);
        }
    
        @Override
        public String getName(CatalogComponent catalogComponent) { 
            return this.name;
        }
    
        @Override
        public void remove(CatalogComponent catalogComponent) { 
            items.remove(catalogComponent);
        }
    
        @Override
        public void print() { 
            System.out.println(this.name);
            for(CatalogComponent catalogComponent : items){ 
                if(this.level != null){ 
                    for(int  i = 0; i < this.level; i++){ 
                        System.out.print(" ");
                    }
                }
                catalogComponent.print();
            }
        }
    
    }

主节点，叶子结点

CatalogComponent linuxCourse = new Course("Linux课程",11);
            CatalogComponent windowsCourse = new Course("Windows课程",11);
    
            CatalogComponent javaCourseCatalog = new CourseCatalog("Java课程目录",2);
    
            CatalogComponent mmallCourse1 = new Course("Java电商一期",55);
            CatalogComponent mmallCourse2 = new Course("Java电商二期",66);
            CatalogComponent designPattern = new Course("Java设计模式",77);
    
            javaCourseCatalog.add(mmallCourse1);
            javaCourseCatalog.add(mmallCourse2);
            javaCourseCatalog.add(designPattern);
    
            CatalogComponent imoocMainCourseCatalog = new CourseCatalog("课程主目录",1);
            imoocMainCourseCatalog.add(linuxCourse);
            imoocMainCourseCatalog.add(windowsCourse);
            imoocMainCourseCatalog.add(javaCourseCatalog);
    
            imoocMainCourseCatalog.print();

打印结果：

课程主目录
      Course Name:Linux课程 Price:11.0
      Course Name:Windows课程 Price:11.0
      Java课程目录
        Course Name:Java电商一期 Price:55.0
        Course Name:Java电商二期 Price:66.0
        Course Name:Java设计模式 Price:77.0