设计模式原则之：迪米特法则

不符合迪米特法则的案例

import java.util.ArrayList;
import java.util.List;

/**
 * @description: 不符合迪米特法则的案例
 * @author: abel.he
 * @date: 2023-08-06
 **/
public class Test {

    public static void main(String[] args) {
        CollegeEmployeeManager manager = new CollegeEmployeeManager();
        EmployeeManager employeeManager = new EmployeeManager();
        employeeManager.printAll(manager);
    }
}

/**
 * 学校总部员工类
 */
class Employee {

    private String id;

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }
}

/**
 * 学院档案的员工类
 */
class CollegeEmployee {

     private String collegeEmployeeId;

    public String getCollegeEmployeeId() {
        return collegeEmployeeId;
    }

    public void setCollegeEmployeeId(String collegeEmployeeId) {
        this.collegeEmployeeId = collegeEmployeeId;
    }
}

/**
 * 员工档案管理类
 */
class CollegeEmployeeManager {

    public List<CollegeEmployee> getAllList() {
        List<CollegeEmployee> result = new ArrayList<>();
        for (int i = 0; i < 5; i++) {
            CollegeEmployee employee = new CollegeEmployee();
            employee.setCollegeEmployeeId("我是学院档案员工：" + i);
            result.add(employee);
        }
        return result;
    }
}

/**
 * 员工管理类
 * Employee 直接的朋友(返回值)
 * CollegeEmployee 不是直接朋友 陌生类 违反了迪米特法则
 *
 */
class EmployeeManager {

    public List<Employee> getEmployee() {
        List<Employee> result = new ArrayList<>();
        for (int i = 0; i < 10; i++) {
            Employee employee = new Employee();
            employee.setId("我是学校总部员工 " + i);
            result.add(employee);
        }

        return result;
    }

    /**
     * 输出所有数据 学校总部员工+学院档案员工信息
     * @param collegeEmployeeManager
     */
    public void printAll(CollegeEmployeeManager collegeEmployeeManager) {
        List<CollegeEmployee> collegeEmployeeManagerAllList = collegeEmployeeManager.getAllList();
        for (CollegeEmployee employee : collegeEmployeeManagerAllList) {
            System.out.println(employee.getCollegeEmployeeId());
        }

        List<Employee> employeeList = this.getEmployee();
        for (Employee employee : employeeList) {
            System.out.println(employee.getId());
        }


    }

}

改成迪米特法则实现

import java.util.ArrayList;
import java.util.List;

/**
 * @description: 迪米特法则的案例
 * @author: abel.he
 * @date: 2023-08-06
 **/
public class Test {

    public static void main(String[] args) {
        CollegeEmployeeManager manager = new CollegeEmployeeManager();
        EmployeeManager employeeManager = new EmployeeManager();
        employeeManager.printAll(manager);
    }
}

/**
 * 学校总部员工类
 */
class Employee {

    private String id;

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }
}

/**
 * 学院档案的员工类
 */
class CollegeEmployee {

     private String collegeEmployeeId;

    public String getCollegeEmployeeId() {
        return collegeEmployeeId;
    }

    public void setCollegeEmployeeId(String collegeEmployeeId) {
        this.collegeEmployeeId = collegeEmployeeId;
    }
}

/**
 * 员工档案管理类
 */
class CollegeEmployeeManager {

    public List<CollegeEmployee> getAllList() {
        List<CollegeEmployee> result = new ArrayList<>();
        for (int i = 0; i < 5; i++) {
            CollegeEmployee employee = new CollegeEmployee();
            employee.setCollegeEmployeeId("我是学院档案员工：" + i);
            result.add(employee);
        }
        return result;
    }

    public void printCollegeEmployeeManager() {
        List<CollegeEmployee> collegeEmployeeManagerAllList = getAllList();
        for (CollegeEmployee employee : collegeEmployeeManagerAllList) {
            System.out.println(employee.getCollegeEmployeeId());
        }
    }
}

/**
 * 员工管理类
 * Employee 直接的朋友(返回值)
 *
 */
class EmployeeManager {

    public List<Employee> getEmployee() {
        List<Employee> result = new ArrayList<>();
        for (int i = 0; i < 10; i++) {
            Employee employee = new Employee();
            employee.setId("我是学校总部员工 " + i);
            result.add(employee);
        }

        return result;
    }

    /**
     * 输出所有数据 学校总部员工+学院档案员工信息
     * @param collegeEmployeeManager
     */
    public void printAll(CollegeEmployeeManager collegeEmployeeManager) {
        // 将输出的方法封装到CollegeEmployeeManager中
        collegeEmployeeManager.printCollegeEmployeeManager();

        List<Employee> employeeList = this.getEmployee();
        for (Employee employee : employeeList) {
            System.out.println(employee.getId());
        }


    }

}