DesignPattern_Java:Composite Pattern

组合模式 Composite Pattern 合成模式

compose objects into tree structures to represent part-whole hierarchies.Composite lets clients treat individual objects and compositions of objects uniformly.

将对象组合成树形结构以表示“部分-整体”的层次结构，使得用户对单个对象和组合对象的使用具有一致性。

抽象构件角色（Component）：该角色定义参加组合对象的共有方法和属性，规范一些默认的行为接口。

package com.DesignPattern.Structural.Composite;
//定义抽象构建接口
public interface Component {
public void operation();
}

叶子构件角色（Leaf）：该角色是叶子对象，其下没有其他的分支，定义出参加组合的原始对象的行为。

package com.DesignPattern.Structural.Composite;//定义叶子构件public class Leaf implements Component {    @Override    public void operation() {        //业务逻辑代码        System.out.println("Leaf operation");    }}

树枝构件角色（Composite）：该角色代表参加组合的、其下的分支的树枝对象，他的作用是将树枝和叶子组合成一个树形结构，并定义出管理子对象的方法，如add()、remove()等。

package com.DesignPattern.Structural.Composite;import java.util.ArrayList;//定义树枝构件public class Composite implements Component {    // 构件容器    private ArrayList<Component> componentList = new ArrayList<Component>();    // 添加构件    public void add(Component component) {        this.componentList.add(component);    }    // 删除构件    public void remove(Component component) {        this.componentList.remove(component);    }    // 获取子构件    public ArrayList<Component> getChild() {        return this.componentList;    }    @Override    public void operation() {        // 业务逻辑代码        System.out.println("Composite operation");    }}

Client

package com.DesignPattern.Structural.Composite;public class Client {    public static void main(String[] args) {        // 创建一个根节点        Composite root = new Composite();        root.operation();        // 创建树枝节点        Composite branch = new Composite();        // 创建叶子节点        Leaf leaf = new Leaf();        // 构件树形结构        root.add(branch);        branch.add(leaf);        display(root);    }    // 遍历树（递归）    public static void display(Composite root) {        for (Component c : root.getChild()) {            if (c instanceof Leaf) { // 如果节点类型是叶子节点                c.operation();            } else { // 树枝节点                c.operation();                display((Composite) c); // 递归调用            }        }    }}

组合模式的实例

Company.java

package com.DesignPattern.Structural.Composite;//抽象接口public interface Company {    //获取信息    public String getInfo();}

ConcreteCompany.java

package com.DesignPattern.Structural.Composite;import java.util.ArrayList;//树枝节点类public class ConcreteCompany implements Company {    private ArrayList<Company> companyList = new ArrayList<Company>();    private String name;    private String position;    private int salary;    //构造函数    public ConcreteCompany(String name, String position, int salary) {        this.name = name;   //姓名        this.position = position; //职位        this.salary = salary;   //薪水    }    public void add(Company company){        this.companyList.add(company);    }    public void remove(Company company){        this.companyList.remove(company);    }    public ArrayList<Company> getChild(){        return this.companyList;    }    @Override    public String getInfo() {        String info="";        info="名称:"+this.name;        info=info+"\t职位："+this.position;        info=info+"\t薪水："+this.salary;        return info;    }}

Employee.java

package com.DesignPattern.Structural.Composite;//叶子节点类public class Employee implements Company {    private String name;    private String position;    private int salary;    public Employee(String name, String position, int salary) {        this.name = name;        this.position = position;        this.salary = salary;    }    @Override    public String getInfo() {        String info="";        info="名称:"+this.name;        info=info+"\t职位："+this.position;        info=info+"\t薪水："+this.salary;        return info;    }}

ClientDemo.java

package com.DesignPattern.Structural.Composite;public class ClientDemo {    public static void main(String[] args){        //CEO        ConcreteCompany root=new ConcreteCompany("Hello","CEO",100000);        //部门经理        ConcreteCompany developDep=new ConcreteCompany("developDep","研发部经理",12000);        ConcreteCompany salesDep=new ConcreteCompany("salesDep","销售部经理",12000);        ConcreteCompany financeDep=new ConcreteCompany("financeDep","财务部经理",12000);        //部门员工        Employee e1=new Employee("A","研发部",3000);        Employee e2=new Employee("B","研发部",3000);        Employee e3=new Employee("C","销售部",3000);        Employee e4=new Employee("D","销售部",3000);        Employee e5=new Employee("E","财务部",3000);        Employee e6=new Employee("F","财务部",3000);        //生成树        root.add(developDep);        root.add(salesDep);        root.add(financeDep);        developDep.add(e1);        developDep.add(e2);        salesDep.add(e3);        salesDep.add(e4);        financeDep.add(e5);        financeDep.add(e6);        System.out.println(root.getInfo());        display(root);    }    //遍历树（递归）    public static void display(ConcreteCompany root){        for(Company c:root.getChild()){            if(c instanceof Employee){  //如果节点类型是叶子节点                System.out.println(c.getInfo());            }else{      //树枝节点                System.out.println("\n"+c.getInfo());                display((ConcreteCompany)c);    //递归调用            }        }    }}