java小白设计模式之观察者模式

2018-06-18 01:59:24来源：未知阅读 ()

观察者模式:
    对象之间多对一依赖的一种设计方案,被依赖对象为Subject(一),依赖对象为Observer(多),Subject通知Observer变化
直接代码:

package com.wz.twoObserver;


public interface Subject {

    public void add(Observer student);

    public void del(Observer student);

    public void mNotify();
}

package com.wz.twoObserver;

public interface Observer {

    public void update(String name, String sex, String subject);

}

package com.wz.twoObserver;

import java.util.ArrayList;

/**
 * 教师类
 *
 * @author Administrator
 * @create 2018-04-18 11:50
 */
public class Teacher implements Subject{

    private String name;

    private String sex;
    // 学科
    private String subject;

    private ArrayList<Observer> studentList;

    // 记住要将集合初始化
    public Teacher() {
        this.studentList = new ArrayList<>();
    }

    public String getName() {
        return name;
    }

    public String getSex() {
        return sex;
    }

    public String getSubject() {
        return subject;
    }

    public void teacherUpdate(){
        mNotify();
    }

    public void setTeacher(String name, String sex, String subject){
        this.name = name;
        this.sex = sex;
        this.subject = subject;
        teacherUpdate();
    }

    @Override
    public void add(Observer student) {
        studentList.add(student);
    }

    @Override
    public void del(Observer student) {
        studentList.remove(student);
    }

    @Override
    public void mNotify() {
        for (int i = 0; i < studentList.size() ; i++) {
            studentList.get(i).update(name,sex,subject);
        }
    }
}

package com.wz.twoObserver;

/**
 * 学生类
 *
 * @author Administrator
 * @create 2018-04-18 11:53
 */
public class Student implements Observer{

    private String name;

    private String sex;
    // 学科
    private String subject;

    @Override
    public void update(String name, String sex, String subject){
        this.name = name;
        this.sex = sex;
        this.subject = subject;
        display();
    }

    public void display(){
        System.out.println("教师姓名:" + name);
        System.out.println("教师的性别:" + sex);
        System.out.println("教师的学科:" + subject);
        System.out.println("=================================");
    }

}

package com.wz.twoObserver;

/**
 * 学生类
 *
 * @author Administrator
 * @create 2018-04-18 11:53
 */
public class Student1 implements Observer{

    private String name;

    private String sex;
    // 学科
    private String subject;

    @Override
    public void update(String name, String sex, String subject){
        this.name = name;
        this.sex = sex;
        this.subject = subject;
        display();
    }

    public void display(){
        System.out.println("教师姓名:" + name);
        System.out.println("教师的性别:" + sex);
        System.out.println("教师的学科:" + subject);
        System.out.println("=================================");
    }

}

package com.wz.twoObserver;

/**
 * 学生类
 *
 * @author Administrator
 * @create 2018-04-18 11:53
 */
public class Student2 implements Observer{

    private String name;

    private String sex;
    // 学科
    private String subject;

    @Override
    public void update(String name, String sex, String subject){
        this.name = name;
        this.sex = sex;
        this.subject = subject;
        display();
    }

    public void display(){
        System.out.println("教师姓名:" + name);
        System.out.println("教师的性别:" + sex);
        System.out.println("教师的学科:" + subject);
        System.out.println("=================================");
    }

}

package com.wz.twoObserver;

/**
 * 测试类
 *
 * @author Administrator
 * @create 2018-04-18 12:12
 */
public class TestMain {

    public static void main(String[] args) {
        Teacher t1 = new Teacher();
        Student s = new Student();;
        Student1 s1 = new Student1();;
        Student2 s2 = new Student2();

        t1.add(s);
        t1.add(s1);
        t1.add(s2);
        t1.setTeacher("郑爽","女","舞蹈");
        System.out.println("======================================");
        t1.del(s);
        t1.setTeacher("杨洋","男","演技");



    }

}


自我感觉这个模式不是特别的理解,看的视频是以天气预报为例,我这以教师和学生为例,开始郑爽老师有3个学生,后来换成杨洋老师了,学生s就退学了,就剩下学生s1和s2的