package com.yanyu.Subscribe1;
import java.util.Observable;
public class Thief extends Observable {
private String name;
public Thief(String name) {
this.name = name;
}
public void setName(String name) {
this.name = name;
}
public String getName() {
return name;
}
public void steal() {
System.out.println("小偷：我偷东西了，有没有人来抓我！！！");
super.setChanged(); //changed = true
super.notifyObservers();
}
}
警察是一个观察者，所以需要让其实现Observer接口
java复制代码
package com.yanyu.Subscribe1;
import java.util.Observable;
import java.util.Observer;
public class Policemen implements Observer {
private String name;
public Policemen(String name) {
this.name = name;
}
public void setName(String name) {
this.name = name;
}
public String getName() {
return name;
}
@Override
public void update(Observable o, Object arg) {
System.out.println("警察：" + ((Thief) o).getName() + "，我已经盯你很久了，你可以保持沉默，但你所说的将成为呈堂证供！！！");
}
}
客户端代码
java复制代码
package com.yanyu.Subscribe1;
public class Client {
public static void main(String[] args) {
//创建小偷对象
Thief t = new Thief("隔壁老王");
//创建警察对象
Policemen p = new Policemen("小李");
//让警察盯着小偷
t.addObserver(p);
//小偷偷东西
t.steal();
}
}
package com.yanyu.visitor;
public interface Person {
void feed(Cat cat);
void feed(Dog dog);
}
具体访问者角色
java复制代码
package com.yanyu.visitor;
public class Owner implements Person {
@Override
public void feed(Cat cat) {
System.out.println("主人喂食猫");
}
@Override
public void feed(Dog dog) {
System.out.println("主人喂食狗");
}
}
抽象元素（Element）角色
java复制代码
package com.yanyu.visitor;
public interface Animal {
void accept(Person person);
}
具体元素角色
java复制代码
package com.yanyu.visitor;
public class Dog implements Animal {
@Override
public void accept(Person person) {
person.feed(this);
System.out.println("好好吃，汪汪汪！！！");
}
}
java复制代码
package com.yanyu.visitor;
public class Cat implements Animal {
@Override
public void accept(Person person) {
person.feed(this);
System.out.println("好好吃，喵喵喵！！！");
}
}
对象结构（Object Structure）角色
java复制代码
package com.yanyu.visitor;
import java.util.ArrayList;
import java.util.List;
public class Home {
private List<Animal> nodeList = new ArrayList<Animal>();
public void action(Person person) {
for (Animal node : nodeList) {
node.accept(person);
}
}
//添加操作
public void add(Animal animal) {
nodeList.add(animal);
}
}
客户端角色
java复制代码
package com.yanyu.visitor;
public class Client {
public static void main(String[] args) {
Home home = new Home();
home.add(new Dog());
// home.add(new Cat());
Owner owner = new Owner();
home.action(owner);
Someone someone = new Someone();
home.action(someone);
}
}
public class Animal {
public void execute() {
System.out.println("Animal");
}
}
public class Dog extends Animal {
@Override
public void execute() {
System.out.println("dog");
}
}
public class Cat extends Animal {
@Override
public void execute() {
System.out.println("cat");
}
}
public class Client {
public static void main(String[] args) {
Animal a = new Dog();
a.execute();
Animal a1 = new Cat();
a1.execute();
}
}
public class Animal {
}
public class Dog extends Animal {
}
public class Cat extends Animal {
}
public class Execute {
public void execute(Animal a) {
System.out.println("Animal");
}
public void execute(Dog d) {
System.out.println("dog");
}
public void execute(Cat c) {
System.out.println("cat");
}
}
public class Client {
public static void main(String[] args) {
Animal a = new Animal();
Animal a1 = new Dog();
Animal a2 = new Cat();
Execute exe = new Execute();
exe.execute(a);
exe.execute(a1);
exe.execute(a2);
}
}
package step1;
import java.util.List;
public class Farmland {
private String name;
private double size;
private List<String> crops;///土地上种植的作物
public Farmland(String location, double size, List<String> crops) {
this.name = location;
this.size = size;
this.crops = crops;
}
public String getName() {
return name;
}
public double getSize() {
return size;
}
public List<String> getCrops() {
return crops;
}
}
具体同事类（Concrete Colleague）角色
java复制代码
package step1;
public class ExpertAdviceSystem {
private Mediator mediator;
public ExpertAdviceSystem(Mediator mediator) {
this.mediator = mediator;
}
public void provideAdvice(Farmland farmland, String pest) {
// 模拟向农民提供预防和治疗建议的过程
String advice = "请及时采取相应的防治措施";
System.out.println("农民" + farmland.getName() + "收到了关于" + pest + "的建议：" + advice);
}
}
java复制代码
package step1;
public class PestDetectionSystem {
private Mediator mediator;
public PestDetectionSystem(Mediator mediator) {
this.mediator = mediator;
}
public void detectPest(String farmland, String pest) {
// 模拟程序中病虫害检测功能忽略，直接发出警报
mediator.notify(this, "pestDetected", farmland, pest);
}
}
客户端类
java复制代码
package step1;
import java.util.Hashtable;
/**
* FarmlandManagementSystem acts as a mediator to connect various subsystems.
* FarmlandManagementSystem充当中介者，串联起各子系统。
*/
public class FarmlandManagementSystem implements Mediator {
private Hashtable farmlands = new Hashtable(); // Hashtable用于存储农田信息
private PestDetectionSystem pestDetectionSystem; // 用于虫害检测的子系统
private ExpertAdviceSystem expertAdviceSystem; // 用于农民建议的子系统
/**
* Add a farmland to the system.
* 将农田添加到系统中。
* @param farmland The farmland to be added. 要添加的农田
*/
public void addFarmland(Farmland farmland) {
if (!farmlands.contains(farmland)) {
farmlands.put(farmland.getName(), farmland); // 将农田信息存入Hashtable
}
}
/**
* Remove a farmland from the system.
* 从系统中移除农田。
* @param farmland The farmland to be removed. 要移除的农田
*/
public void removeFarmland(Farmland farmland) {
farmlands.remove(farmland); // 从Hashtable中移除农田信息
}
/**
* Set the pest detection system for the mediator.
* 为中介者设置虫害检测系统。
* @param pestDetectionSystem The pest detection system to be set. 要设置的虫害检测系统
*/
public void setPestDetectionSystem(PestDetectionSystem pestDetectionSystem) {
this.pestDetectionSystem = pestDetectionSystem; // 设置虫害检测子系统
}
/**
* Set the farmer advice system for the mediator.
* 为中介者设置农民建议系统。
* @param expertAdviceSystem The expert advice system to be set. 要设置的农民建议系统
*/
public void setFarmerAdviceSystem(ExpertAdviceSystem expertAdviceSystem) {
this.expertAdviceSystem = expertAdviceSystem; // 设置农民建议子系统
}
/**
* Notify the mediator about an event and take appropriate action.
* 通知中介者有关事件，并采取适当的行动。
* @param sender The object that sends the notification. 发送通知的对象
* @param event The event being notified. 被通知的事件
* @param land The land related to the event. 与事件相关的土地
* @param pest The pest related to the event. 与事件相关的虫害
*/
@Override
public void notify(Object sender, String event, String land, String pest) {
if (event.equals("pestDetected")) { // 如果事件是虫害检测
Farmland farmland = (Farmland) farmlands.get(land); // 获取与事件相关的农田信息
expertAdviceSystem.provideAdvice(farmland, pest); // 调用农民建议子系统提供建议
}
}
}
package step1;
public class GrowthVisitors implements CropVisitor{
@Override
public void visit(TomatoCrop tomatoCrop) {
System.out.println(tomatoCrop.getName() + "生长监控完成");
}
@Override
public void visit(CucumberCrop cucumberCrop) {
System.out.println(cucumberCrop.getName() + "生长监控完成");
}
@Override
public void visit(CauliflowerCrop cauliflowerCrop) {
System.out.println(cauliflowerCrop.getName() + "生长监控完成");
}
}
java复制代码
package step1;
/********** Begin *********/
public class PestsVisitors implements CropVisitor{
@Override
public void visit(TomatoCrop tomatoCrop) {
System.out.println(tomatoCrop.getName() + "病虫害监控完成");
}
@Override
public void visit(CucumberCrop cucumberCrop) {
System.out.println(cucumberCrop.getName() + "病虫害监控完成");
}
@Override
public void visit(CauliflowerCrop cauliflowerCrop) {
System.out.println(cauliflowerCrop.getName() + "病虫害监控完成");
}
}
/********** End *********/
对象结构（Object Structure）角色
java复制代码
package step1;
import java.util.ArrayList;
import java.util.Iterator;
/**
* CropGroup represents a group of crops and provides methods to add, remove, and accept visitors.
* CropGroup表示一组农作物，提供添加、移除和接受访问者的方法。
*/
public class CropGroup {
private ArrayList list = new ArrayList(); // 用ArrayList存储农作物
/**
* Accept a visitor to visit all crops in the group.
* 接受访问者访问组中的所有农作物。
* @param visitor The visitor to be accepted. 要接受的访问者
*/
public void accept(CropVisitor visitor) {
Iterator i = list.iterator(); // 使用迭代器遍历所有农作物
while (i.hasNext()) {
((Crop) i.next()).accept(visitor); // 调用每个农作物的accept方法，让访问者访问该农作物
}
}
/**
* Add a crop to the group.
* 将一个农作物添加到组中。
* @param crop The crop to be added. 要添加的农作物
*/
public void addCrop(Crop crop) {
list.add(crop); // 将农作物添加到ArrayList中
}
/**
* Remove a crop from the group.
* 从组中移除一个农作物。
* @param crop The crop to be removed. 要移除的农作物
*/
public void removeProduct(Crop crop) {
list.remove(crop); // 从ArrayList中移除农作物
}
}
客户端类
java复制代码
package step1;
public class Client {
public static void main(String[] args) {
CucumberCrop cucumberCrop=new CucumberCrop("黄瓜实验田1");
CauliflowerCrop cauliflowerCrop = new CauliflowerCrop("花菜实验田2");
TomatoCrop tomatoCrop = new TomatoCrop("番茄实验田3");
CropGroup cropgroup = new CropGroup();
cropgroup.addCrop(cucumberCrop);
cropgroup.addCrop(cauliflowerCrop);
cropgroup.addCrop(tomatoCrop);
CropVisitor visitor = new GrowthVisitors();
cropgroup.accept(visitor);
/********** Begin *********/
CropVisitor visitor2 = new PestsVisitors();
cropgroup.accept(visitor2);
/********** End *********/
}
}
2.2结构
