每次學習新東西，接觸新領域的時候，常常會想學了後能應用到什麼地方。用了它能改善什麼東西，為什麼非他不可？

1.訂閱與釋出是啥：我個人的理解是：你關注了某個人，他發了一條資訊，你能馬上知道。

知道了是啥，有哪些技術能實現我需要的這種功能呢：腦海裡，網上搜索一番，發現類似的開源產品還是很多的。譬如：Redis，ActiveMQ，RabbitMQ等等。

先來說說理論上的的實現：以Redis為例：java來實現。

第一步：訂閱頻道：繼承JedisPubSub，重寫其下的多個方法：然後寫個主方法去訂閱：

public class PubRedis extends JedisPubSub{
	@Override
    public  void onMessage(String channel, String message) {
	    System.out.println("訊息: 來自頻道["+channel+"], 的訊息：["+message+"]");
    }

 

    @Override
    public void onPMessage(String pattern, String channel, String message) {
    	System.out.println("模式:"+pattern);
    	System.out.println("頻道:"+channel);
    	System.out.println("訊息:"+message);
    }

 

    @Override
    public void onSubscribe(String channel,int subscribedChannels) {
        System.out.println("onSubscribe: channel["+channel+"],"+
                                                "subscribedChannels["+subscribedChannels+"]");
    }

 

    @Override

    public void onUnsubscribe(String channel,int subscribedChannels) {
        System.out.println("onUnsubscribe: channel["+channel+"], "+

                                               "subscribedChannels["+subscribedChannels+"]");
    }

 

    @Override

    public void onPUnsubscribe(String pattern,int subscribedChannels) {
        System.out.println("onPUnsubscribe: pattern["+pattern+"],"+
                                               "subscribedChannels["+subscribedChannels+"]");
    }

 

    @Override

    public void onPSubscribe(String pattern,int subscribedChannels) {
        System.out.println("onPSubscribe: pattern["+pattern+"], "+

                                               "subscribedChannels["+subscribedChannels+"]");
    }
	public static void main(String[] args) {
        Jedis jr = null;
        try {
            jr = new Jedis("localhost", 6379, 0);//redis服務地址和埠號
            PubRedis sp = new PubRedis();
            sp.proceed(jr.getClient(),"news.share", "news.blog");   //訂閱了"news.share", "news.blog"兩個頻道
            //sp.proceedWithPatterns(jr.getClient(), "news.*");

        } catch (Exception e) {
            e.printStackTrace();
        }
        finally{
            if(jr!=null){
                jr.disconnect();
            }
        }
    }

}
 

public class PublishMasage {
public static void main(String str[])
{
	 Jedis jr = null;
     try {
         jr = new Jedis("localhost", 6379, 0);//redis服務地址和埠號
         jr.publish("news.blog", "發一條只有1和2都有的");
     } catch (Exception e) {
         e.printStackTrace();
     }

     finally{
         if(jr!=null){
             jr.disconnect();
         }

     }
}
}