1.引出迭代器模式
1.展示院系结构
![image-20240615212257547](https://img-blog.csdnimg.cn/img_convert/27e62fd887558283dd2bed5b1aff53b3.png)
2.传统方式
![image-20240615212357982](https://img-blog.csdnimg.cn/img_convert/cae94650b80e4be93357d4bb302d6c58.png)
2.迭代器模式解决院系结构展示问题
1.基本介绍
![image-20240615212618599](https://img-blog.csdnimg.cn/img_convert/26a012736fb2406755252b7bdf5e7588.png)
2.原理类图
![image-20240615213958769](https://img-blog.csdnimg.cn/img_convert/35b368f167eecc4e971d3fce23646582.png)
3.类图
![image-20240616200949550](https://img-blog.csdnimg.cn/img_convert/8fdad6b29d2c6407bbc82aeedcef1f26.png)
4.代码实现
1.Department.java 存储信息的对象
package com.sun;
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;
public interface College {
String getName();
void addDepartment(String name, String desc);
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;
public class ComputerCollege implements College {
Department[] departments;
int numOfDepartment = 0;
public ComputerCollege() {
departments = new Department[3];
addDepartment("java", "java");
addDepartment("python", "python");
addDepartment("go", "go");
}
@Override
public String getName() {
return "计算机学院";
}
@Override
public void addDepartment(String name, String desc) {
Department department = new Department(name, desc);
departments[numOfDepartment++] = department;
}
@Override
public Iterator createIterator() {
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;
public class ComputerCollegeIterator implements Iterator {
Department[] departments;
int position = 0;
public ComputerCollegeIterator(Department[] departments) {
this.departments = departments;
}
@Override
public boolean hasNext() {
if(position >= departments.length || departments[position] == null) {
return false;
}
return true;
}
@Override
public Object next() {
Department department = departments[position];
position += 1;
return department;
}
@Override
public 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;
public class InfoCollege implements College{
List<Department> departmentList;
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");
}
@Override
public String getName() {
return "信息工程学院";
}
@Override
public void addDepartment(String name, String desc) {
Department department = new Department(name, desc);
departmentList.add(department);
}
@Override
public 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;
public class InfoColleageIterator implements Iterator {
List<Department> departments;
int index = -1;
public InfoColleageIterator(List<Department> departments) {
this.departments = departments;
}
@Override
public boolean hasNext() {
if (index >= departments.size() - 1) {
return false;
}
index += 1;
return true;
}
@Override
public Object next() {
return departments.get(index);
}
@Override
public 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;
public class OutputImpl {
List<College> collegeList;
public OutputImpl(List<College> collegeList) {
this.collegeList = collegeList;
}
public void printCollege() {
for (College college : collegeList) {
System.out.println("=====" + college.getName() + "=====");
Iterator iterator = college.createIterator();
printDepartment(iterator);
}
}
public void printDepartment(Iterator iterator) {
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;
public class Client {
public static void main(String[] args) {
List<College> collegeList = new LinkedList<>();
collegeList.add(new ComputerCollege());
collegeList.add(new InfoCollege());
OutputImpl output = new OutputImpl(collegeList);
output.printCollege();
}
}
5.注意事项和细节
![image-20240617195403899](https://img-blog.csdnimg.cn/img_convert/91740bb75251896aa8295b7954d77043.png)
3.迭代器模式在ArrayList的应用
![](https://img-blog.csdnimg.cn/img_convert/71a7be4d7b5dec6ec8115bc89f420ded.png)
观察者模式
1.引出观察者模式
1.天气预报项目需求
![image-20240617195703024](https://img-blog.csdnimg.cn/img_convert/fee30a4c096fc9efa093be55fa5013cc.png)
2.普通方案
![image-20240617200144645](https://img-blog.csdnimg.cn/img_convert/0cd93a6b075f9aa42e213c2cb606f335.png)
![image-20240617200256420](https://img-blog.csdnimg.cn/img_convert/c34b69e2111cb13ae1cc5ffe5729d874.png)
3.普通方案问题分析
![image-20240617201005774](https://img-blog.csdnimg.cn/img_convert/0947af1e01535bdefc4631bc0843d17e.png)
2.观察者模式解决天气预报
1.原理分析
![image-20240617201208773](https://img-blog.csdnimg.cn/img_convert/569deab2eaa058a28b8aa50d3617b365.png)
![image-20240617201218388](https://img-blog.csdnimg.cn/img_convert/32062ba4dcb4840509a53eb956156c80.png)
2.类图
![image-20240617204226600](https://img-blog.csdnimg.cn/img_convert/977e159f99544e58daa18acfcbcb3053.png)
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;
public interface Observer {
void update(float temperature, float pressure, float humidity);
}
2.CurrentConditions.java 具体的观察者
package com.sun;
public class CurrentConditions implements Observer{
private float temperature;
private float pressure;
private float humidity;
@Override
public void update(float temperature, float pressure, float humidity) {
this.temperature = temperature;
this.humidity = humidity;
this.pressure = pressure;
display();
}
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;
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;
public class WeatherData implements Subject{
private float temperature;
private float pressure;
private float humidity;
private List<Observer> observerList;
public WeatherData() {
observerList = new ArrayList<>();
}
public void setData(float temperature, float pressure, float humidity) {
this.humidity = humidity;
this.pressure = pressure;
this.temperature = temperature;
changeData();
}
public void changeData() {
notifyObservers();
}
@Override
public void registerObserver(Observer o) {
observerList.add(o);
}
@Override
public void removeObserver(Observer o) {
observerList.remove(o);
}
@Override
public void notifyObservers() {
Iterator<Observer> iterator = observerList.iterator();
while (iterator.hasNext()) {
Observer next = iterator.next();
next.update(temperature, pressure, humidity);
}
}
}
5.Client.java
package com.sun;
public class Client {
public static void main(String[] args) {
WeatherData weatherData = new WeatherData();
CurrentConditions currentConditions = new CurrentConditions();
weatherData.registerObserver(currentConditions);
weatherData.setData(200, 200, 200);
weatherData.setData(100, 100, 100);
}
}
6.结果
![image-20240618201732219](https://img-blog.csdnimg.cn/img_convert/9b020cf492022abd09fb7e1c93d30737.png)
3.观察者模式在JDK的Observable类中的使用
![image-20240618201819188](https://img-blog.csdnimg.cn/img_convert/a80de94531460e9f857f737b7905a65f.png)