ElasticJob简单使用

ElasticJob单点使用

任务类

public class BackupJob implements SimpleJob {public void execute(ShardingContext shardingContext) {String selectSql = "select * from resume where state='未归档' limit 1";List<Map<String, Object>> list =JdbcUtil.executeQuery(selectSql);if(list == null || list.size() == 0) {return;}Map<String, Object> stringObjectMap = list.get(0);long id = (long) stringObjectMap.get("id");String name = (String) stringObjectMap.get("name");String education = (String)stringObjectMap.get("education");
// 打印出这条记录System.out.println("======>>>id：" + id + " name：" +name + " education：" + education);
// 更改状态String updateSql = "update resume set state='已归档' where id=?";JdbcUtil.executeUpdate(updateSql,id);
// 归档这条记录String insertSql = "insert into resume_bak select * from resume where id=?";JdbcUtil.executeUpdate(insertSql,id);}}

主要的任务就是将未归档的数据整理到归档的表中，表结构一样执行类

public class JobMain {public static void main(String[] args) {//初始化注册中心ZookeeperConfiguration zookeeperConfiguration = new ZookeeperConfiguration("127.0.0.1:2181","data-job");CoordinatorRegistryCenter coordinatorRegistryCenter= new ZookeeperRegistryCenter(zookeeperConfiguration);coordinatorRegistryCenter.init();//创建任务JobCoreConfiguration jobCoreConfiguration = JobCoreConfiguration.newBuilder("data-job","*/2 * * * * ?",1).build();SimpleJobConfiguration simpleJobConfiguration = new SimpleJobConfiguration(jobCoreConfiguration,BackupJob.class.getName());//执行任务new JobScheduler(coordinatorRegistryCenter, LiteJobConfiguration.newBuilder(simpleJobConfiguration).build()).init();}
}

这种情况下，启动两个任务类只会有一个在执行任务。但是当一个任务停止之后，另一个任务会立马开始接着执行任务，相当于其他中间件中的主备切换。但是这里的主备切换是依托zk进行的

多节点分布式任务调度

修改执行类的代码为

public class JobMain {public static void main(String[] args) {//初始化注册中心ZookeeperConfiguration zookeeperConfiguration = new ZookeeperConfiguration("127.0.0.1:2181","data-job");CoordinatorRegistryCenter coordinatorRegistryCenter= new ZookeeperRegistryCenter(zookeeperConfiguration);coordinatorRegistryCenter.init();//创建任务JobCoreConfiguration jobCoreConfiguration = JobCoreConfiguration.newBuilder("data-job","*/2 * * * * ?",3).build();SimpleJobConfiguration simpleJobConfiguration = new SimpleJobConfiguration(jobCoreConfiguration,BackupJob.class.getName());//执行任务new JobScheduler(coordinatorRegistryCenter, LiteJobConfiguration.newBuilder(simpleJobConfiguration).overwrite(true).build()).init();}
}

除了修改分片数还需要在执行任务的类中执行相应的分片参数，另外需要注意的是仅仅增加分票策略是不生效的，必须同时配置分片参数。另外如果使用同一个job来做执行的话。需要增加overwrite为true 执行器代码为 ``` public class BackupJob implements SimpleJob { public void execute(ShardingContext shardingContext) { int shardingitem = shardingContext.getShardingItem(); System.out.println("当前分片"+shardingitem); String shardingParamter = shardingContext.getShardingParameter(); System.out.println(shardingParamter); String selectSql = "select * from resume where state='未归档' and name='"+shardingParamter+"' limit 1"; List<Map<String, Object>> list = JdbcUtil.executeQuery(selectSql); if(list == null || list.size() == 0) { return; } Map<String, Object> stringObjectMap = list.get(0); long id = (long) stringObjectMap.get("id"); String name = (String) stringObjectMap.get("name"); String education = (String) stringObjectMap.get("education"); // 打印出这条记录 System.out.println("======>>>id：" + id + " name：" + name + " education：" + education); // 更改状态 String updateSql = "update resume set state='已归档' where id=?"; JdbcUtil.executeUpdate(updateSql,id); // 归档这条记录 String insertSql = "insert into resume_bak select * from resume where id=?"; JdbcUtil.executeUpdate(insertSql,id); }

} ``` 测试结果为，当执行器未全部启动时，所有分片在一个执行器上运行。当三个执行器都启动时，会平均分配到三个执行器。

demo代码地址为https://github.com/zhendiao/deme-code/tree/main/schedule_job

欢迎搜索关注本人的公众号【微瞰技术】,以及总结的分类面试题https://github.com/zhendiao/JavaInterview