23种java设计模式详解-观察者模式

1、创建被观察者：

package org.jason.Observer;
import  java.util.Observable;
//被观察者
public class Writer extends Observable {
    private String authorName;
    private Article article;

    public String getAuthorName() {
        return authorName;
    }

    public void setAuthorName(String authorName) {
        this.authorName = authorName;
    }

    public Article getArticle() {
        return article;
    }

    public void setArticle(Article article) {
        this.article = article;
    }

    public  void   publish()
       {
           //设置状态变化
           this.setChanged();
           System.out.println("作者:"+this.getAuthorName()+"  发布新文章啦");
           System.out.println("--标题："+this.getArticle().getTitile());
           System.out.println("--内容："+this.getArticle().getContent());
           //通知所有观察者
           this.notifyObservers();
       }
}

package org.jason.Observer;

public class Article {
    private String titile;
    private String content;

    public String getTitile() {
        return titile;
    }

    public void setTitile(String titile) {
        this.titile = titile;
    }

    public String getContent() {
        return content;
    }

    public void setContent(String content) {
        this.content = content;
    }
}

2、创建观察者：

package org.jason.Observer;
import java.util.Observable;
import java.util.Observer;
//观察者
public class Reader implements Observer{
    private String readerName;

    public String getReaderName() {
        return readerName;
    }

    public void setReaderName(String readerName) {
        this.readerName = readerName;
    }

    @Override
    public void update(Observable o, Object arg) {
        Writer w=(Writer)o;
        Article  a=w.getArticle();
        System.out.println("读者："+this.getReaderName());
        System.out.println("订阅到如下文章：");
        System.out.println("标题："+a.getTitile());
        System.out.println("内容："+a.getContent());
    }
}

3、测试程序：

package org.jason.Observer;

public class TestMain {
    public static void main(String args[])
    {
        Article  article=new Article();
        article.setTitile("设计模式-观察者模式应用");
        article.setContent("...............................");
        Writer  w =new Writer();
        w.setAuthorName("石头城程序猿");

        Reader r1=new Reader();
        r1.setReaderName("张三");
        Reader r2=new Reader();
        r2.setReaderName("李四");
        w.addObserver(r1);
        w.addObserver(r2);

        w.setArticle(article);
        w.publish();
    }
}

4、输出结果：

作者:石头城程序猿  发布新文章啦
--标题：设计模式-观察者模式应用
--内容：...............................
读者：李四
订阅到如下文章：
标题：设计模式-观察者模式应用
内容：...............................
读者：张三
订阅到如下文章：
标题：设计模式-观察者模式应用
内容：...............................