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