生成订单30分钟未支付,则自动取消,该怎么实现?
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2021-08-29 10:14
阅读本文大概需要 10 分钟。
来自:https://blog.csdn.net/hjm4702192/article/details/80519010
# 引言
生成订单30分钟未支付,则自动取消
生成订单60秒后,给用户发短信
定时任务有明确的触发时间,延时任务没有
定时任务有执行周期,而延时任务在某事件触发后一段时间内执行,没有执行周期
定时任务一般执行的是批处理操作是多个任务,而延时任务一般是单个任务
# 方案分析
(1)数据库轮询
思路
实现
maven项目引入一个依赖如下所示
<dependency>
<groupId>org.quartz-scheduler</groupId>
<artifactId>quartz</artifactId>
<version>2.2.2</version>
</dependency>
package com.rjzheng.delay1;
import org.quartz.JobBuilder;
import org.quartz.JobDetail;
import org.quartz.Scheduler;
import org.quartz.SchedulerException;
import org.quartz.SchedulerFactory;
import org.quartz.SimpleScheduleBuilder;
import org.quartz.Trigger;
import org.quartz.TriggerBuilder;
import org.quartz.impl.StdSchedulerFactory;
import org.quartz.Job;
import org.quartz.JobExecutionContext;
import org.quartz.JobExecutionException;
public class MyJob implements Job {
public void execute(JobExecutionContext context)
throws JobExecutionException {
System.out.println("要去数据库扫描啦。。。");
}
public static void main(String[] args) throws Exception {
// 创建任务
JobDetail jobDetail = JobBuilder.newJob(MyJob.class)
.withIdentity("job1", "group1").build();
// 创建触发器 每3秒钟执行一次
Trigger trigger = TriggerBuilder
.newTrigger()
.withIdentity("trigger1", "group3")
.withSchedule(
SimpleScheduleBuilder.simpleSchedule()
.withIntervalInSeconds(3).repeatForever())
.build();
Scheduler scheduler = new StdSchedulerFactory().getScheduler();
// 将任务及其触发器放入调度器
scheduler.scheduleJob(jobDetail, trigger);
// 调度器开始调度任务
scheduler.start();
}
}
要去数据库扫描啦。。。
DelayedQueue实现工作流程如下图所示
take():获取并移除队列的超时元素,如果没有则wait当前线程,直到有元素满足超时条件,返回结果。
实现
package com.rjzheng.delay2;
import java.util.concurrent.Delayed;
import java.util.concurrent.TimeUnit;
public class OrderDelay implements Delayed {
private String orderId;
private long timeout;
OrderDelay(String orderId, long timeout) {
this.orderId = orderId;
this.timeout = timeout + System.nanoTime();
}
public int compareTo(Delayed other) {
if (other == this)
return 0;
OrderDelay t = (OrderDelay) other;
long d = (getDelay(TimeUnit.NANOSECONDS) - t
.getDelay(TimeUnit.NANOSECONDS));
return (d == 0) ? 0 : ((d < 0) ? -1 : 1);
}
// 返回距离你自定义的超时时间还有多少
public long getDelay(TimeUnit unit) {
return unit.convert(timeout - System.nanoTime(),TimeUnit.NANOSECONDS);
}
void print() {
System.out.println(orderId+"编号的订单要删除啦。。。。");
}
}
package com.rjzheng.delay2;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.DelayQueue;
import java.util.concurrent.TimeUnit;
public class DelayQueueDemo {
public static void main(String[] args) {
// TODO Auto-generated method stub
List<String> list = new ArrayList<String>();
list.add("00000001");
list.add("00000002");
list.add("00000003");
list.add("00000004");
list.add("00000005");
DelayQueue<OrderDelay> queue = newDelayQueue<OrderDelay>();
long start = System.currentTimeMillis();
for(int i = 0;i<5;i++){
//延迟三秒取出
queue.put(new OrderDelay(list.get(i),
TimeUnit.NANOSECONDS.convert(3,TimeUnit.SECONDS)));
try {
queue.take().print();
System.out.println("After " +
(System.currentTimeMillis()-start) + " MilliSeconds");
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
00000001编号的订单要删除啦。。。。
After 3003 MilliSeconds
00000002编号的订单要删除啦。。。。
After 6006 MilliSeconds
00000003编号的订单要删除啦。。。。
After 9006 MilliSeconds
00000004编号的订单要删除啦。。。。
After 12008 MilliSeconds
00000005编号的订单要删除啦。。。。
After 15009 MilliSeconds
优缺点
缺点:
(2)集群扩展相当麻烦
(3)因为内存条件限制的原因,比如下单未付款的订单数太多,那么很容易就出现OOM异常
(4)代码复杂度较高
(3)时间轮算法
思路
实现
给Pom加上下面的依赖
<dependency>
<groupId>io.netty</groupId>
<artifactId>netty-all</artifactId>
<version>4.1.24.Final</version>
</dependency>
package com.rjzheng.delay3;
import io.netty.util.HashedWheelTimer;
import io.netty.util.Timeout;
import io.netty.util.Timer;
import io.netty.util.TimerTask;
import java.util.concurrent.TimeUnit;
public class HashedWheelTimerTest {
static class MyTimerTask implements TimerTask{
boolean flag;
public MyTimerTask(boolean flag){
this.flag = flag;
}
public void run(Timeout timeout) throws Exception {
// TODO Auto-generated method stub
System.out.println("要去数据库删除订单了。。。。");
this.flag =false;
}
}
public static void main(String[] argv) {
MyTimerTask timerTask = new MyTimerTask(true);
Timer timer = new HashedWheelTimer();
timer.newTimeout(timerTask, 5, TimeUnit.SECONDS);
int i = 1;
while(timerTask.flag){
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
System.out.println(i+"秒过去了");
i++;
}
}
}
1秒过去了
2秒过去了
3秒过去了
4秒过去了
5秒过去了
要去数据库删除订单了。。。。
6秒过去了
添加元素:ZADD key score member [[score member] [score member] …]
按顺序查询元素:ZRANGE key start stop [WITHSCORES]
查询元素score:ZSCORE key member
移除元素:ZREM key member [member …]
# 添加单个元素
redis> ZADD page_rank 10 google.com
(integer) 1
# 添加多个元素
redis> ZADD page_rank 9 baidu.com 8 bing.com
(integer) 2
redis> ZRANGE page_rank 0 -1 WITHSCORES
1) "bing.com"
2) "8"
3) "baidu.com"
4) "9"
5) "google.com"
6) "10"
# 查询元素的score值
redis> ZSCORE page_rank bing.com
"8"
# 移除单个元素
redis> ZREM page_rank google.com
(integer) 1
redis> ZRANGE page_rank 0 -1 WITHSCORES
1) "bing.com"
2) "8"
3) "baidu.com"
4) "9"
实现一
package com.rjzheng.delay4;
import java.util.Calendar;
import java.util.Set;
import redis.clients.jedis.Jedis;
import redis.clients.jedis.JedisPool;
import redis.clients.jedis.Tuple;
public class AppTest {
private static final String ADDR = "127.0.0.1";
private static final int PORT = 6379;
private static JedisPool jedisPool = new JedisPool(ADDR, PORT);
public static Jedis getJedis() {
return jedisPool.getResource();
}
//生产者,生成5个订单放进去
public void productionDelayMessage(){
for(int i=0;i<5;i++){
//延迟3秒
Calendar cal1 = Calendar.getInstance();
cal1.add(Calendar.SECOND, 3);
int second3later = (int) (cal1.getTimeInMillis() / 1000);
AppTest.getJedis().zadd("OrderId",second3later,"OID0000001"+i);
System.out.println(System.currentTimeMillis()+"ms:redis生成了一个订单任务:订单ID为"+"OID0000001"+i);
}
}
//消费者,取订单
public void consumerDelayMessage(){
Jedis jedis = AppTest.getJedis();
while(true){
Set<Tuple> items = jedis.zrangeWithScores("OrderId", 0, 1);
if(items == null || items.isEmpty()){
System.out.println("当前没有等待的任务");
try {
Thread.sleep(500);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
continue;
}
int score = (int) ((Tuple)items.toArray()[0]).getScore();
Calendar cal = Calendar.getInstance();
int nowSecond = (int) (cal.getTimeInMillis() / 1000);
if(nowSecond >= score){
String orderId = ((Tuple)items.toArray()[0]).getElement();
jedis.zrem("OrderId", orderId);
System.out.println(System.currentTimeMillis() +"ms:redis消费了一个任务:消费的订单OrderId为"+orderId);
}
}
}
public static void main(String[] args) {
AppTest appTest =new AppTest();
appTest.productionDelayMessage();
appTest.consumerDelayMessage();
}
}
package com.rjzheng.delay4;
import java.util.concurrent.CountDownLatch;
public class ThreadTest {
private static final int threadNum = 10;
private static CountDownLatch cdl = newCountDownLatch(threadNum);
static class DelayMessage implements Runnable{
public void run() {
try {
cdl.await();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
AppTest appTest =new AppTest();
appTest.consumerDelayMessage();
}
}
public static void main(String[] args) {
AppTest appTest =new AppTest();
appTest.productionDelayMessage();
for(int i=0;i<threadNum;i++){
new Thread(new DelayMessage()).start();
cdl.countDown();
}
}
}
if(nowSecond >= score){
String orderId = ((Tuple)items.toArray()[0]).getElement();
jedis.zrem("OrderId", orderId);
System.out.println(System.currentTimeMillis()+"ms:redis消费了一个任务:消费的订单OrderId为"+orderId);
}
if(nowSecond >= score){
String orderId = ((Tuple)items.toArray()[0]).getElement();
Long num = jedis.zrem("OrderId", orderId);
if( num != null && num>0){
System.out.println(System.currentTimeMillis()+"ms:redis消费了一个任务:消费的订单OrderId为"+orderId);
}
}
notify-keyspace-events Ex
package com.rjzheng.delay5;
import redis.clients.jedis.Jedis;
import redis.clients.jedis.JedisPool;
import redis.clients.jedis.JedisPubSub;
public class RedisTest {
private static final String ADDR = "127.0.0.1";
private static final int PORT = 6379;
private static JedisPool jedis = new JedisPool(ADDR, PORT);
private static RedisSub sub = new RedisSub();
public static void init() {
new Thread(new Runnable() {
public void run() {
jedis.getResource().subscribe(sub, "__keyevent@0__:expired");
}
}).start();
}
public static void main(String[] args) throws InterruptedException {
init();
for(int i =0;i<10;i++){
String orderId = "OID000000"+i;
jedis.getResource().setex(orderId, 3, orderId);
System.out.println(System.currentTimeMillis()+"ms:"+orderId+"订单生成");
}
}
static class RedisSub extends JedisPubSub {
<ahref='http://www.jobbole.com/members/wx610506454'>@Override</a>
public void onMessage(String channel, String message) {
System.out.println(System.currentTimeMillis()+"ms:"+message+"订单取消");
}
}
}
ps:redis的pub/sub机制存在一个硬伤,官网内容如下
原:Because Redis Pub/Sub is fire and forget currently there is no way to use this feature if your application demands reliable notification of events, that is, if your Pub/Sub client disconnects, and reconnects later, all the events delivered during the time the client was disconnected are lost.
翻: Redis的发布/订阅目前是即发即弃(fire and forget)模式的,因此无法实现事件的可靠通知。也就是说,如果发布/订阅的客户端断链之后又重连,则在客户端断链期间的所有事件都丢失了。
因此,方案二不是太推荐。当然,如果你对可靠性要求不高,可以使用。
优缺点
(2)做集群扩展相当方便
(3)时间准确度高
(5)使用消息队列
RabbitMQ可以针对Queue和Message设置 x-message-tt,来控制消息的生存时间,如果超时,则消息变为dead letter
lRabbitMQ的Queue可以配置x-dead-letter-exchange 和x-dead-letter-routing-key(可选)两个参数,用来控制队列内出现了deadletter,则按照这两个参数重新路由。
结合以上两个特性,就可以模拟出延迟消息的功能,具体的,我改天再写一篇文章,这里再讲下去,篇幅太长。
优缺点
缺点:本身的易用度要依赖于rabbitMq的运维.因为要引用rabbitMq,所以复杂度和成本变高。
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