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软件设计师案例分析每日一练试题内容(2022/7/26)
阅读下列说明和Java代码,将应填入 (n)处的字句卸载答题纸的对应栏内.
【说明】
某实验室欲建立一个实验室环境监测系统,能够显示实验室的温度、湿度以及洁净度等环境数据。当获取到最新的环境测量数据时,显示的环境数据能够更新。
现在采用观察者(Observer)模式来开发该系统。观察者模式的类图如图6-1所示。
【Java代码】
import java.util.*;
interface Observer {
public void update(float temp, float humidity, float cleanness);
}
interface Subject {
public void registerObserver(Observer o); //注册对主题感兴趣的观察者
public void removeObserver(Observer o); //删除观察者
public void notifyObservers(); //当主题发生变化时通知观察者
}
class EnvironmentData implements (1) {
private ArrayList observers;
private float temperature, humidity, cleanness;
public EnvironmentData() { observers = new ArrayList(); }
public void registerObserver(Observer o) { observers.add(o); }
public void removeObserver(Observer o) { /* 代码省略 */ }
public void notifyObservers() {
for (int i = 0; i < observers.size(); i++) {
Observer observer = (Observer)observers.get(i);
(2) ;
}
}
public void measurementsChanged() { (3) ; }
public void setMeasurements(float temperature, float humidity, float cleanness) {
this.temperature = temperature;
this.humidity = humidity;
this.cleanness = cleanness;
(4) ;
}
}
class CurrentConditionsDisplay implements (5) {
private float temperature;
private float humidity;
private float cleanness;
private Subject envData;
public CurrentConditionsDisplay(Subject envData) {
this.envData = envData;
(6) ;
}
public void update(float temperature, float humidity, float cleanness) {
this.temperature = temperature;
this.humidity = humidity;
this.cleanness = cleanness;
display();
}
public void display() {/* 代码省略 */ }
}
class EnvironmentMonitor{
public static void main(String[] args) {
EnvironmentData envData = new EnvironmentData();
CurrentConditionsDisplay currentDisplay = new CnrrentConditionsDisplay(envData);
envData.setMeasurements(80, 65, 30.4f);
}
}
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