利用 Hazelcast SQL 查询 IMap 数据：构建高性能任务管理系统

import com.hazelcast.client.HazelcastClient;
import com.hazelcast.core.HazelcastInstance;
import com.hazelcast.map.IMap;
import com.hazelcast.sql.SqlResult;
import com.hazelcast.sql.SqlRow;
import com.hazelcast.sql.SqlService;

public class HazelcastSQLDemo {

    public static void main(String[] args) {
        // 创建 Hazelcast 实例
        HazelcastInstance hazelcastInstance = HazelcastClient.newHazelcastClient();

        // 获取 IMap 实例
        IMap<Integer, Task> tasks = hazelcastInstance.getMap("delayed_tasks");

        // 填充一些示例数据
        tasks.put(1, new Task(1, "TYPE_A", "ACTION_X", 3, null, 0));
        tasks.put(2, new Task(2, "TYPE_B", "ACTION_Y", 1, null, 1));
        tasks.put(3, new Task(3, "TYPE_A", "ACTION_Z", 0, null, 0));

        // 获取 SQL 服务
        SqlService sqlService = hazelcastInstance.getSql();

        // 执行 SQL 查询
        String sql = "SELECT id, type, action, retries FROM delayed_tasks WHERE action_required = 1 and is_currently_running = 0 ORDER BY id ASC LIMIT 1";
        SqlResult result = sqlService.execute(sql);

        // 处理查询结果
        for (SqlRow row : result) {
            System.out.println("ID: " + row.getObject("id"));
            System.out.println("Type: " + row.getObject("type"));
            System.out.println("Action: " + row.getObject("action"));
            System.out.println("Retries: " + row.getObject("retries"));
        }

        // 关闭 Hazelcast 实例
        hazelcastInstance.shutdown();
    }

    // 任务类
    static class Task {
        private int id;
        private String type;
        private String action;
        private int retries;
        private String penalty_date;
        private int is_currently_running;

        public Task(int id, String type, String action, int retries, String penalty_date, int is_currently_running) {
            this.id = id;
            this.type = type;
            this.action = action;
            this.retries = retries;
            this.penalty_date = penalty_date;
            this.is_currently_running = is_currently_running;
        }

        public int getId() {
            return id;
        }

        public String getType() {
            return type;
        }

        public String getAction() {
            return action;
        }

        public int getRetries() {
            return retries;
        }

        public String getPenalty_date() {
            return penalty_date;
        }

        public int getIs_currently_running() {
            return is_currently_running;
        }
    }
}

import com.hazelcast.core.HazelcastInstance;
import com.hazelcast.core.Hazelcast;
import com.hazelcast.map.IMap;
import com.hazelcast.map.MapStore;
import com.hazelcast.map.MapStoreFactory;

import java.util.Collection;
import java.util.HashMap;
import java.util.Map;

public class MapStoreDemo {

    public static void main(String[] args) {
        // 创建 Hazelcast 实例
        HazelcastInstance hazelcastInstance = Hazelcast.newHazelcastInstance();

        // 获取 IMap 实例，并配置 MapStore
        IMap<Integer, String> map = hazelcastInstance.getMap("myMap");
        map.put(1, "Value 1");
        map.put(2, "Value 2");

        // 强制将数据写入 MapStore
        map.flush();

        // 关闭 Hazelcast 实例
        hazelcastInstance.shutdown();
    }

    // 自定义 MapStore 实现
    public static class MyMapStore implements MapStore<Integer, String> {

        private Map<Integer, String> store = new HashMap<>();

        @Override
        public void store(Integer key, String value) {
            System.out.println("Storing: " + key + " -> " + value);
            store.put(key, value);
        }

        @Override
        public void storeAll(Map<Integer, String> map) {
            System.out.println("Storing all: " + map);
            store.putAll(map);
        }

        @Override
        public String load(Integer key) {
            System.out.println("Loading: " + key);
            return store.get(key);
        }

        @Override
        public Map<Integer, String> loadAll(Collection<Integer> keys) {
            System.out.println("Loading all: " + keys);
            Map<Integer, String> result = new HashMap<>();
            for (Integer key : keys) {
                String value = store.get(key);
                if (value != null) {
                    result.put(key, value);
                }
            }
            return result;
        }

        @Override
        public Iterable<Integer> loadAllKeys() {
            System.out.println("Loading all keys");
            return store.keySet();
        }

        @Override
        public void delete(Integer key) {
            System.out.println("Deleting: " + key);
            store.remove(key);
        }

        @Override
        public void deleteAll(Collection<Integer> keys) {
            System.out.println("Deleting all: " + keys);
            for (Integer key : keys) {
                store.remove(key);
            }
        }
    }

    // 自定义 MapStoreFactory 实现
    public static class MyMapStoreFactory implements MapStoreFactory<Integer, String> {

        @Override
        public MapStore<Integer, String> newMapStore(String mapName, Properties properties) {
            return new MyMapStore();
        }
    }
}