设计模式

1、工厂设计模式

用来生产类对象，避免用户直接接触派生类

给出一个例子：

接口：Teacher

interface Teacher{
	public void teach();
}

class EnglishTeacher implements Teacher{
	public void teach(){
		System.out.println("上英语课");
	}
}

class MathTeacher implements Teacher{
	public void teach(){
		System.out.println("上数学课");
	}
}

class TeacherFactory{
	public static Teacher getTeacher(int flag){
		Teacher teacher = null;
		if(0 == flag){
			teacher = new EnglishTeacher();
		}
		else if(1 == flag ){
			teacher = new MathTeacher();
		}
		return teacher;
	}
}

class Test{
	public static void main(String args []){
		int flag = 1;
		Teacher teacher = TeacherFactory.getTeacher(flag);
		teacher.teach();
	}
}

 

2、装饰者设计模式

主要用于降低继承的复杂度

在上面的基础上修改代码

class GradeOne implements Teacher{
	Teacher gradeOneTeacher = null;
	GradeOne(Teacher teacher){
		gradeOneTeacher = teacher;
	}
	public void teach(){
		System.out.println("我是一年级的老师");
		gradeOneTeacher.teach();
	}
}

class GradeTwo implements Teacher{
	Teacher gradeTwoTeacher = null;
	GradeTwo(Teacher teacher){
		gradeTwoTeacher = teacher;
	}
	public void teach(){
		System.out.println("我是二年级的老师");
		gradeTwoTeacher.teach();
	}
}

class Test{
	public static void main(String args []){
	
		//下面的方法是申请一个一年级的数学老师
		//装饰者模式
		int flag = 1;
		Teacher teacher = TeacherFactory.getTeacher(flag);
		GradeOne gradeOneTeacher = new GradeOne(teacher);
		gradeOneTeacher.teach();
	}
}