消息队列的场景：发布订阅，生产消费。
Redis 2.0之后开始支持pub/sub，所以可以使用下这个。
--------------------------------------------------------------非持久化订阅-------------------------------------------------------
===========PrintListener.java:订阅者消息处理器===================
public class PrintListener extends JedisPubSub{
@Override
public void onMessage(String channel, String message) {
String time = DateFormatUtils.format(new Date(), "yyyy-MM-dd HH:mm:ss");
System.out.println("message receive:" + message + ",channel:" + channel + "..." + time);
//此处我们可以取消订阅
if(message.equalsIgnoreCase("quit")){
this.unsubscribe(channel);
}
}
...
}
================PubClient.java:消息发布端================
public class PubClient {
private Jedis jedis;//
public PubClient(String host,int port){
jedis = new Jedis(host,port);
}
public void pub(String channel,String message){
jedis.publish(channel, message);
}
public void close(String channel){
jedis.publish(channel, "quit");
jedis.del(channel);//
}
}
========SubClient.java:消息订阅端========
public class SubClient {
private Jedis jedis;//
public SubClient(String host,int port){
jedis = new Jedis(host,port);
}
public void sub(JedisPubSub listener,String channel){
jedis.subscribe(listener, channel);
//此处将会阻塞，在client代码级别为JedisPubSub在处理消息时，将会“独占”链接
//并且采取了while循环的方式，侦听订阅的消息
//
}
}
=============PubSubTestMain.java:测试引导类===============
public class PubSubTestMain {
/**
* @param args
*/
public static void main(String[] args) throws Exception{
PubClient pubClient = new PubClient(Constants.host, Constants.port);
final String channel = "pubsub-channel";
pubClient.pub(channel, "before1");
pubClient.pub(channel, "before2");
Thread.sleep(2000);
//消息订阅着非常特殊，需要独占链接，因此我们需要为它创建新的链接；
//此外，jedis客户端的实现也保证了“链接独占”的特性，sub方法将一直阻塞，
//直到调用listener.unsubscribe方法
Thread subThread = new Thread(new Runnable() {
@Override
public void run() {
try{
SubClient subClient = new SubClient(Constants.host, Constants.port);
System.out.println("----------subscribe operation begin-------");
JedisPubSub listener = new PrintListener();
//在API级别，此处为轮询操作，直到unsubscribe调用，才会返回
subClient.sub(listener, channel);
System.out.println("----------subscribe operation end-------");
}catch(Exception e){
e.printStackTrace();
}
}
});
subThread.start();
int i=0;
while(i < 10){
String message = RandomStringUtils.random(6, true, true);//apache-commons
pubClient.pub(channel, message);
i++;
Thread.sleep(1000);
}
//被动关闭指示，如果通道中，消息发布者确定通道需要关闭，那么就发送一个“quit”
//那么在listener.onMessage()中接收到“quit”时，其他订阅client将执行“unsubscribe”操作。
pubClient.close(channel);
//此外，你还可以这样取消订阅
//listener.unsubscribe(channel);
}
}
--------------------------------------------------------------持久化订阅-------------------------------------------------------
基本思路：当订阅者订阅消息时，将此订阅者信息添加到一个列表中，此列表为“所有订阅者列表”，同时为每个订阅者都创建一个保存消息（内容或者消息ID）的队列，消息发布者将每条消息都添加到每个订阅者的队列中。
如下实现仅供参考，有很多更优的实现方式。
============PPrintListener.java============
public class PPrintListener extends JedisPubSub{
private String clientId;
private PSubHandler handler;
public PPrintListener(String clientId,Jedis jedis){
this.clientId = clientId;
handler = new PSubHandler(jedis);
}
@Override
public void onMessage(String channel, String message) {
//此处我们可以取消订阅
if(message.equalsIgnoreCase("quit")){
this.unsubscribe(channel);
}
handler.handle(channel, message);//触发当前订阅者从自己的消息队列中移除消息
}
private void message(String channel,String message){
String time = DateFormatUtils.format(new Date(), "yyyy-MM-dd HH:mm:ss");
System.out.println("message receive:" + message + ",channel:" + channel + "..." + time);
}
@Override
public void onPMessage(String pattern, String channel, String message) {
System.out.println("message receive:" + message + ",pattern channel:" + channel);
}
@Override
public void onSubscribe(String channel, int subscribedChannels) {
handler.subscribe(channel);
System.out.println("subscribe:" + channel + ";total channels : " + subscribedChannels);
}
@Override
public void onUnsubscribe(String channel, int subscribedChannels) {
handler.unsubscribe(channel);
System.out.println("unsubscribe:" + channel + ";total channels : " + subscribedChannels);
}
@Override
public void onPUnsubscribe(String pattern, int subscribedChannels) {
System.out.println("unsubscribe pattern:" + pattern + ";total channels : " + subscribedChannels);
}
@Override
public void onPSubscribe(String pattern, int subscribedChannels) {
System.out.println("subscribe pattern:" + pattern + ";total channels : " + subscribedChannels);
}
@Override
public void unsubscribe(String... channels) {
super.unsubscribe(channels);
for(String channel : channels){
handler.unsubscribe(channel);
}
}
class PSubHandler {
private Jedis jedis;
PSubHandler(Jedis jedis){
this.jedis = jedis;
}
public void handle(String channel,String message){
int index = message.indexOf("/");
if(index < 0){
return;
}
Long txid = Long.valueOf(message.substring(0,index));
String key = clientId + "/" + channel;
while(true){
String lm = jedis.lindex(key, 0);//获取第一个消息
if(lm == null){
break;
}
int li = lm.indexOf("/");
//如果消息不合法，删除并处理
if(li < 0){
String result = jedis.lpop(key);//删除当前message
//为空
if(result == null){
break;
}
message(channel, lm);
continue;
}
Long lxid = Long.valueOf(lm.substring(0,li));//获取消息的txid
//直接消费txid之前的残留消息
if(txid >= lxid){
jedis.lpop(key);//删除当前message
message(channel, lm);
continue;
}else{
break;
}
}
}
public void subscribe(String channel){
String key = clientId + "/" + channel;
boolean exist = jedis.sismember(Constants.SUBSCRIBE_CENTER,key);
if(!exist){
jedis.sadd(Constants.SUBSCRIBE_CENTER, key);
}
}
public void unsubscribe(String channel){
String key = clientId + "/" + channel;
jedis.srem(Constants.SUBSCRIBE_CENTER, key);//从“活跃订阅者”集合中删除
jedis.del(key);//删除“订阅者消息队列”
}
}
}
=============PPubClient.java====================
public class PPubClient {
private Jedis jedis;//
public PPubClient(String host,int port){
jedis = new Jedis(host,port);
}
/**
* 发布的每条消息，都需要在“订阅者消息队列”中持久
* @param message
*/
private void put(String message){
//期望这个集合不要太大
Set<String> subClients = jedis.smembers(Constants.SUBSCRIBE_CENTER);
for(String clientKey : subClients){
jedis.rpush(clientKey, message);
}
}
public void pub(String channel,String message){
//每个消息，都有具有一个全局唯一的id
//txid为了防止订阅端在数据处理时“乱序”，这就要求订阅者需要解析message
Long txid = jedis.incr(Constants.MESSAGE_TXID);
String content = txid + "/" + message;
//非事务
this.put(content);
jedis.publish(channel, content);//为每个消息设定id，最终消息格式1000/messageContent
}
public void close(String channel){
jedis.publish(channel, "quit");
jedis.del(channel);//删除
}
public void test(){
jedis.set("pub-block", "15");
String tmp = jedis.get("pub-block");
System.out.println("TEST:" + tmp);
}
}
======================PPSubClient.java==================
public class PSubClient {
private Jedis jedis;//
private JedisPubSub listener;//单listener
public PSubClient(String host,int port,String clientId){
jedis = new Jedis(host,port);
listener = new PPrintListener(clientId, new Jedis(host, port));
}
public void sub(String channel){
jedis.subscribe(listener, channel);
}
public void unsubscribe(String channel){
listener.unsubscribe(channel);
}
}
===============PPubSubTestMain.java==================
public class PPubSubTestMain {
/**
* @param args
*/
public static void main(String[] args) throws Exception{
PPubClient pubClient = new PPubClient(Constants.host, Constants.port);
final String channel = "pubsub-channel-p";
final PSubClient subClient = new PSubClient(Constants.host, Constants.port,"subClient-1");
Thread subThread = new Thread(new Runnable() {
@Override
public void run() {
System.out.println("----------subscribe operation begin-------");
//在API级别，此处为轮询操作，直到unsubscribe调用，才会返回
subClient.sub(channel);
System.out.println("----------subscribe operation end-------");
}
});
subThread.setDaemon(true);
subThread.start();
int i = 0;
while(i < 2){
String message = RandomStringUtils.random(6, true, true);//apache-commons
pubClient.pub(channel, message);
i++;
Thread.sleep(1000);
}
subClient.unsubscribe(channel);
}
}null
