軟件設(shè)計模式之組合模式
組合模式根據(jù)樹結(jié)構(gòu)組成對象，以表示部分以及整個層次結(jié)構(gòu)。
組合模式用于需要以類似方式將一組對象視為單個對象的情況。組合模式根據(jù)樹結(jié)構(gòu)組成對象，以表示部分以及整個層次結(jié)構(gòu)。這種設(shè)計模式屬于結(jié)構(gòu)模式，因為該模式創(chuàng)建了一組對象的樹形結(jié)構(gòu)。此模式創(chuàng)建一個包含其自己的對象組的類。此類提供了修改其相同對象組的方法。
我們通過以下示例演示復(fù)合模式的使用，在該示例中我們將顯示組織的員工層次結(jié)構(gòu)。
實作
我們有一個Employee類，它充當(dāng)復(fù)合模式參與者類。CompositePatternDemo，我們的演示類將使用Employee類添加部門級別的層次結(jié)構(gòu)并打印所有員工。
第1步
創(chuàng)建員工具有列表類員工的對象。
Employee.java
import java.util.ArrayList;
import java.util.List;
public class Employee {
private String name;
private String dept;
private int salary;
private List<Employee> subordinates;
// constructor
public Employee(String name,String dept, int sal) {
this.name = name;
this.dept = dept;
this.salary = sal;
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;
}
public String toString(){
return ("Employee :[ Name : " + name + ", dept : " + dept + ", salary :" + salary+" ]");
}
}
第2步
使用Employee類創(chuàng)建和打印員工層次結(jié)構(gòu)。
CompositePatternDemo.java
public class CompositePatternDemo {
public static void main(String[] args) {
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);
//print all employees of the organization
System.out.println(CEO);
for (Employee headEmployee : CEO.getSubordinates()) {
System.out.println(headEmployee);
for (Employee employee : headEmployee.getSubordinates()) {
System.out.println(employee);
}
}
}
}
第三步
驗證輸出。
Employee :[ Name : John, dept : CEO, salary :30000 ]
Employee :[ Name : Robert, dept : Head Sales, salary :20000 ]
Employee :[ Name : Richard, dept : Sales, salary :10000 ]
Employee :[ Name : Rob, dept : Sales, salary :10000 ]
Employee :[ Name : Michel, dept : Head Marketing, salary :20000 ]
Employee :[ Name : Laura, dept : Marketing, salary :10000 ]
Employee :[ Name : Bob, dept : Marketing, salary :10000 ]