迭代器模式观察者模式

1.引出迭代器模式

1.展示院系结构

2.传统方式

2.迭代器模式解决院系结构展示问题

1.基本介绍

2.原理类图

3.类图

4.代码实现

1.Department.java 存储信息的对象

package com.sun;/*** Description: 系* @Author sun* @Create 2024/6/16 20:11* @Version 1.0*/
public class Department {private String name;private String desc;public Department(String name, String desc) {this.name = name;this.desc = desc;}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getDesc() {return desc;}public void setDesc(String desc) {this.desc = desc;}
}

2.College.java 被迭代的类型接口

package com.sun;import java.util.Iterator;/*** Description:* @Author sun* @Create 2024/6/16 20:31* @Version 1.0*/
public interface College {// 获取大学的名字String getName();// 添加一个系void addDepartment(String name, String desc);// 创建迭代器Iterator createIterator();}

3.ComputerCollege.java 被迭代的具体实现类，存储数据并将其在创建迭代器的时候传进去

package com.sun;import java.util.Iterator;/*** Description: 具体的学院* @Author sun* @Create 2024/6/16 20:35* @Version 1.0*/
public class ComputerCollege implements College {// 数组类型的元素Department[] departments;// 保存当前数组的对象个数int numOfDepartment = 0;/*** 初始化数组*/public ComputerCollege() {departments = new Department[3];addDepartment("java", "java");addDepartment("python", "python");addDepartment("go", "go");}/*** 获取当前学院的名字* @return*/@Overridepublic String getName() {return "计算机学院";}/*** 添加要遍历的元素* @param name* @param desc*/@Overridepublic void addDepartment(String name, String desc) {Department department = new Department(name, desc);departments[numOfDepartment++] = department;}/*** 创建迭代器* @return*/@Overridepublic Iterator createIterator() {// 创建一个迭代器并将元素放进去return new ComputerCollegeIterator(departments);}
}

4.ComputerCollegeIterator.java 被实现的具体类的迭代器

package com.sun;import java.util.Iterator;/*** Description:* @Author sun* @Create 2024/6/16 20:13* @Version 1.0*/
public class ComputerCollegeIterator implements Iterator {// 构造器聚合Department，也就是要遍历的元素，这里的是数组的形式Department[] departments;// 遍历的位置int position = 0;public ComputerCollegeIterator(Department[] departments) {this.departments = departments;}/*** 数组的形式判断是否有下一个元素，其实就是判断当前位置有没有元素* @return*/@Overridepublic boolean hasNext() {if(position >= departments.length || departments[position] == null) {return false;}return true;}/*** 数组的形式取出下一个元素，其实就是取出当前元素，然后将下标加一* @return*/@Overridepublic Object next() {Department department = departments[position];position += 1;return department;}/*** 删除的方法默认空实现*/@Overridepublic void remove() {Iterator.super.remove();}
}

5.InfoCollege.java 被迭代的具体类型

package com.sun;import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;/*** Description: 具体的学院* @Author sun* @Create 2024/6/16 20:41* @Version 1.0*/
public class InfoCollege implements College{// 集合类型的元素List<Department> departmentList;/*** 初始化具体的学院信息*/public InfoCollege() {departmentList = new LinkedList<>();addDepartment("信息安全", "信息安全");addDepartment("网络安全", "网络安全");addDepartment("服务器安全", "服务器安全");}/*** 获取名称* @return*/@Overridepublic String getName() {return "信息工程学院";}/*** 集合的方式添加元素* @param name* @param desc*/@Overridepublic void addDepartment(String name, String desc) {Department department = new Department(name, desc);departmentList.add(department);}/*** 创建迭代器* @return*/@Overridepublic Iterator createIterator() {return new InfoColleageIterator(departmentList);}
}

6.InfoColleageIterator.java 具体的迭代器

package com.sun;import java.util.Iterator;
import java.util.List;/*** Description:* @Author sun* @Create 2024/6/16 20:25* @Version 1.0*/
public class InfoColleageIterator implements Iterator {// 集合类型的List<Department> departments;// 未遍历元素的前一个位置int index = -1;public InfoColleageIterator(List<Department> departments) {this.departments = departments;}/*** 集合的方式判断是否有下一个位置* @return*/@Overridepublic boolean hasNext() {if (index >= departments.size() - 1) {return false;}// 如果有下一个位置，直接指向下一个位置index += 1;return true;}/*** 集合的方式获取下一个元素* @return*/@Overridepublic Object next() {return departments.get(index);}/*** 删除方法空实现*/@Overridepublic void remove() {Iterator.super.remove();}
}

7.OutputImpl.java 统一输出信息的类

package com.sun;import java.util.Iterator;
import java.util.List;/*** Description: 输出* @Author sun* @Create 2024/6/16 20:46* @Version 1.0*/
public class OutputImpl {// 构造器聚合学院集合，才能够输出List<College> collegeList;public OutputImpl(List<College> collegeList) {this.collegeList = collegeList;}// 遍历所有学院，然后输出各个学院的系public void printCollege() {// 从学院集合中得到各个学院的迭代器，然后进行遍历for (College college : collegeList) {// 得到学院System.out.println("=====" + college.getName() + "=====");// 得到学院的迭代器Iterator iterator = college.createIterator();// 遍历printDepartment(iterator);}}// 输出学院，输出系public void printDepartment(Iterator iterator) {// 根据得到的迭代器进行遍历while (iterator.hasNext()) {Department next = (Department) iterator.next();System.out.println(next.getName());}}}

8.Client.java 客户端

package com.sun;import java.util.LinkedList;
import java.util.List;/*** Description:* @Author sun* @Create 2024/6/16 20:59* @Version 1.0*/
public class Client {public static void main(String[] args) {// 创建两个学院，放到集合中List<College> collegeList = new LinkedList<>();collegeList.add(new ComputerCollege());collegeList.add(new InfoCollege());// 遍历OutputImpl output = new OutputImpl(collegeList);output.printCollege();}
}

5.注意事项和细节

3.迭代器模式在ArrayList的应用

观察者模式

1.引出观察者模式

1.天气预报项目需求

2.普通方案

3.普通方案问题分析

2.观察者模式解决天气预报

1.原理分析

2.类图

3.代码实现

1.Observer.java 观察者接口，可以更新自己的信息

package com.sun;/*** Description: 观察者接口* @Author sun* @Create 2024/6/17 20:28* @Version 1.0*/
public interface Observer {void update(float temperature, float pressure, float humidity);}

2.CurrentConditions.java 具体的观察者

package com.sun;/*** Description: 具体的观察者* @Author sun* @Create 2024/6/17 20:30* @Version 1.0*/
public class CurrentConditions implements Observer{private float temperature;private float pressure;private float humidity;/*** 更新并显示数据* @param temperature* @param pressure* @param humidity*/@Overridepublic void update(float temperature, float pressure, float humidity) {this.temperature = temperature;this.humidity = humidity;this.pressure = pressure;display();}/*** 显示*/public void display() {System.out.println("Today's temperature: " + temperature);System.out.println("Today's pressure: " + pressure);System.out.println("Today's humidity: " + humidity);}}

3.Subject.java 信息发布者的接口

package com.sun;/*** Description:* @Author sun* @Create 2024/6/17 20:27* @Version 1.0*/
public interface Subject {void registerObserver(Observer o);void removeObserver(Observer o);void notifyObservers();}

4.WeatherData.java 具体的信息发布者，一旦更新信息就会更新观察者的信息

package com.sun;import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;/*** Description: 包含最新的天气，和观察者集合，当更新时会依次通知各个观察者* @Author sun* @Create 2024/6/17 20:36* @Version 1.0*/
public class WeatherData implements Subject{/*天气信息*/private float temperature;private float pressure;private float humidity;/*观察者集合*/private List<Observer> observerList;/*** 初始化*/public WeatherData() {observerList = new ArrayList<>();}/*** 设置数据* @param temperature* @param pressure* @param humidity*/public void setData(float temperature, float pressure, float humidity) {this.humidity = humidity;this.pressure = pressure;this.temperature = temperature;changeData();}/*** 当数据改变时会通知所有的观察者*/public void changeData() {notifyObservers();}/*** 注册观察者* @param o*/@Overridepublic void registerObserver(Observer o) {observerList.add(o);}/*** 移除观察者* @param o*/@Overridepublic void removeObserver(Observer o) {observerList.remove(o);}/*** 遍历所有的观察者并通知*/@Overridepublic void notifyObservers() {// 这里使用迭代器遍历（只要能遍历就可以）Iterator<Observer> iterator = observerList.iterator();while (iterator.hasNext()) {Observer next = iterator.next();// 更新next.update(temperature, pressure, humidity);}}}

5.Client.java

package com.sun;/*** Description:* @Author sun* @Create 2024/6/17 21:02* @Version 1.0*/
public class Client {public static void main(String[] args) {// 创建一个有天气数据的对象WeatherData weatherData = new WeatherData();// 创建观察者CurrentConditions currentConditions = new CurrentConditions();// 注册观察者weatherData.registerObserver(currentConditions);// 修改天气状况weatherData.setData(200, 200, 200);// 再修改一下天气状况weatherData.setData(100, 100, 100);}}

6.结果

3.观察者模式在JDK的Observable类中的使用