静态工厂方法是否在内部使用new关键字在Java中创建对象?
工厂模式是一种设计模式(创意模式),用于根据我们提供的数据创建多个对象。在其中,我们创建了一个抽象创建过程的对象。
示例
下面给出了工厂模式的示例实现。在这里,我们有一个名为Employee和3类的接口:Student,讲师,NonTeachingStaff,实现了它。我们使用名为的方法创建了一个工厂类(EmployeeFactory)getEmployee()
。此方法接受String值,并根据给定的String值返回其中一个类的对象。
import java.util.Scanner; interface Person{ void dsplay(); } class Student implements Person{ public void dsplay() { System.out.println("This is display method of the Student class"); } } class Lecturer implements Person{ public void dsplay() { System.out.println("This is display method of the Lecturer class"); } } class NonTeachingStaff implements Person{ public void dsplay() { System.out.println("This is display method of the NonTeachingStaff class"); } } class PersonFactory{ public Person getPerson(String empType) { if(empType == null){ return null; } if(empType.equalsIgnoreCase("student")){ return new Student(); } else if(empType.equalsIgnoreCase("lecturer")){ return new Lecturer(); } else if(empType.equalsIgnoreCase("non teaching staff")){ return new NonTeachingStaff(); } return null; } } public class FactoryPattern { public static void main(String args[]) { Scanner sc = new Scanner(System.in); System.out.println("Enter the type of the object you want: (student, lecturer, non teaching staff)"); String type = sc.next(); PersonFactory obj = new PersonFactory(); Person emp = obj.getPerson(type); emp.dsplay(); } }
输出结果
Enter the type of the object you want: (student, lecturer, non teaching staff) lecturer This is display method of the Lecturer class
静态工厂方法
虽然据说有五种方法可以在Java中创建对象-
使用new关键字。
使用工厂方法。
使用克隆。
使用Class.forName()。
使用对象反序列化。
用Java创建对象的唯一方法是使用new关键字,其他所有方法都是对该对象的抽象。所有这些方法在内部都完整地使用new关键字。
示例
import java.util.Scanner; interface Employee{ void dsplay(); } class Student implements Employee{ public void dsplay() { System.out.println("This is display method of the Student class"); } } class Lecturer implements Employee{ public void dsplay() { System.out.println("This is display method of the Lecturer class"); } } class NonTeachingStaff implements Employee{ public void dsplay() { System.out.println("This is display method of the NonTeachingStaff class"); } } class EmployeeFactory{ public static Employee getEmployee(String empType) { if(empType == null){ return null; } if(empType.equalsIgnoreCase("student")){ return new Student(); } else if(empType.equalsIgnoreCase("lecturer")){ return new Lecturer(); } else if(empType.equalsIgnoreCase("non teaching staff")){ return new NonTeachingStaff(); } return null; } } public class FactoryPattern { public static void main(String args[]) { Scanner sc = new Scanner(System.in); System.out.println("Enter the type of the object you want: (student, lecturer, non teaching staff)"); String type = sc.next(); EmployeeFactory obj = new EmployeeFactory(); Employee emp = EmployeeFactory.getEmployee(type); emp.dsplay(); } }
输出结果
Enter the type of the object you want: (student, lecturer, non teaching staff) lecturer This is display method of the Lecturer class