资阳建网站,网站统计器,注册网站需要注意什么,wordpress静态化首页定义#xff1a;定义了对象之间的一对多依赖#xff0c;让多个观察者对象同时监听某一个主题对象#xff0c;当主题对象发生变化时#xff0c;它的依赖者#xff08;观察者#xff09;都会收到通知并更新 适用场景#xff1a; 关联行为场景#xff0c;建立一套触发机制…定义定义了对象之间的一对多依赖让多个观察者对象同时监听某一个主题对象当主题对象发生变化时它的依赖者观察者都会收到通知并更新 适用场景 关联行为场景建立一套触发机制 优点 1.观察者和被观察者之间建立一个抽象的耦合 2.观察者模式支持广播通讯 缺点 观察者之间有过多的细节依赖提高时间消耗及程序复杂度 使用得当要避免循环调用 import java.util.Observable;public class Course extends Observable {private String courseName;public Course(String courseName) {this.courseName courseName;}public String getCourseName() {return courseName;}public void produceQuestion(Course course,Question question){System.out.println(question.getUserName()在course.courseName提交了问题);setChanged();notifyObservers(question);}
}public class Question {private String userName;private String questionContent;public String getUserName() {return userName;}public void setUserName(String userName) {this.userName userName;}public String getQuestionContent() {return questionContent;}public void setQuestionContent(String questionContent) {this.questionContent questionContent;}
}import java.util.Observable;
import java.util.Observer;public class Teacher implements Observer {private String teacherName;public Teacher(String teacherName) {this.teacherName teacherName;}Overridepublic void update(Observable o,Object arg){Course course(Course)o;Question question(Question)arg;System.out.println(teacherName老师的course.getCourseName()课程接收到一个question.getUserName()提交的问答question.getQuestionContent());}
}public class Test {public static void main(String[] args) {Course coursenew Course(Java设计模式精讲);Teacher teachernew Teacher(laoshi);course.addObserver(teacher);Question questionnew Question();question.setUserName(Geelly);question.setQuestionContent(Java);course.produceQuestion(course,question);}
}转载于:https://www.cnblogs.com/sunliyuan/p/10789776.html
