23种设计模式-组合模式

• 主要解决：它在我们树型结构的问题中，模糊了简单元素和复杂元素的概念，客户程序可以像处理简单元素一样来处理复杂元素，从而使得客户程序与复杂元素的内部结构解耦。

以创建和打印员工的层次结构为例，最小单元示例：

• 1、创建 Employee 类，该类带有 Employee 对象的列表。

  public class Employee {
  
      private String name;
      // 部门
      private String dept;
      // 工资
      private int salary;
      // 员工 list
      private List<Employee> subordinates;
  
      public Employee(String name, String dept, int salary) {
          this.name = name;
          this.dept = dept;
          this.salary = salary;
          this.subordinates = new ArrayList<Employee>();
      }
  
      public void add(Employee e) {
          subordinates.add(e);
      }
  
      public void remove(Employee e) {
          subordinates.remove(e);
      }
  
      public List<Employee> getSubordinates() {
          return subordinates;
      }
  
      @Override
      public String toString() {
          return "Employee{" +
                  "name='" + name + '\'' +
                  ", dept='" + dept + '\'' +
                  ", salary=" + salary +
                  ", subordinates=" + subordinates +
                  '}';
      }
  }

  2.使用 Employee 类来创建和打印员工的层次结构。

  final Employee ceo = new Employee("John", "CEO", 30000);
  
  Employee headSales = new Employee("Robert", "Head sales", 20000);
  
  Employee headMarketing = new Employee("Michel", "Head Marketing", 20000);
  
  Employee clerk1 = new Employee("Laura", "Marketing", 10000);
  Employee clerk2 = new Employee("Bob", "Marketing", 10000);
  
  Employee salesExecutive1 = new Employee("Richard", "Sales", 10000);
  Employee salesExecutive2 = new Employee("Rob", "Sales", 10000);
  
  ceo.add(headSales);
  ceo.add(headMarketing);
  
  headSales.add(salesExecutive1);
  headSales.add(salesExecutive2);
  
  headMarketing.add(clerk1);
  headMarketing.add(clerk2);
  
  Log.e("---", ceo.toString());
  
  // 打印
  /*
   * Employee{name='John', dept='CEO', salary=30000,
   * subordinates=[Employee{name='Robert', dept='Head sales', salary=20000,
   * subordinates=[
   * Employee{name='Richard', dept='Sales', salary=10000, subordinates=[]},
   * Employee{name='Rob', dept='Sales', salary=10000, subordinates=[]}]},
   * Employee{name='Michel', dept='Head Marketing', salary=20000,
   * subordinates=[Employee{name='Laura', dept='Marketing', salary=10000, subordinates=[]},
   * Employee{name='Bob', dept='Marketing', salary=10000, subordinates=[]}]}]}
   */