使用 hashMap和treeMap开启多个摄像头的监控任务

背景：今天有个需求，传入多个摄像头ID，然后调用接口，开启这些摄像头的监控任务。

方法一：

如果你的摄像头监控任务格式为：

{camera_id_list=[{createBy=tjt, cameraId=camera01, startTime=2019-1-10 22:58:19}, {createBy=tjt, cameraId=camera02, startTime=2019-1-10 22:58:19}], callback=http://www.baidu.com}

这种格式的话，那么可以用hashMap搞定。

代码如下：

 import java.util.Date;
 import java.util.HashMap;
 import java.util.LinkedList;

 import org.apache.commons.lang.time.DateFormatUtils;

 import lombok.extern.slf4j.Slf4j;

 @Slf4j
 public class HashMapUtil {

     public static void main(String[] args) {
         HashMapUtil.testHashMap("camera01,camera02,camera03");
     }

     public static void testHashMap(String cameraStrList) {
         String[] splitCameraList = cameraStrList.split(",");
         HashMap<String, Object> hashMap = new HashMap<>();
         //add and delete faster than arrayList when using linkList
         LinkedList<Object> linkedList = new LinkedList<>();
         for(String splitCamera : splitCameraList) {
             hashMap.put("cameraId", splitCamera);
             hashMap.put("createBy","tjt");
             hashMap.put("startTime", DateFormatUtils.format(new Date(), "yyyy-MM-dd HH:mm:ss"));
             linkedList.add(hashMap);
             hashMap = new HashMap<>();
         }
         HashMap<Object, Object> paramMap = new HashMap<>();
         paramMap.put("camera_id_list", linkedList);
         paramMap.put("callback", "http://www.baidu.com");
         log.info("linkedList: "+linkedList);
         log.info("paramMap: "+paramMap);
     }

 }

执行结果：

inkedList: [{createBy=tjt, cameraId=camera01, startTime=2019-1-10 22:58:19},{createBy=tjt, cameraId=camera02, startTime=2019-1-10 22:58:19}, {createBy=tjt, cameraId=camera03, startTime=2019-1-10 22:58:19}]
 paramMap: {camera_id_list=[{createBy=tjt, cameraId=camera01, startTime=2019-1-10 22:58:19}, {createBy=tjt, cameraId=camera02, startTime=2019-1-10 22:58:19}, {createBy=tjt, cameraId=camera03, startTime=2019-1-10 22:58:19}], callback=http://www.baidu.com}

方法二：

如果你的摄像头监控任务格式为：

{camera_id_list=[{cameraId=camera01, cameraId=camera02, cameraId=camera03}], callback=http://www.baidu.com}

二叉树treeMap，当传入的两个key值一样，会返回结果0，则会覆盖掉之前的cameraId，返回结果：{camera_id_list=[{cameraId=camera03}], callback=http://www.baidu.com}；

重写了treeMap中的比较方法，当比较结果返回值小于0，则排在二叉树的左边即集合倒序，当比较结果返回值大于0，则排在二叉树的右边亦不会覆盖之前的key值；

代码如下：

 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.LinkedList;
 import java.util.TreeMap;
 import lombok.extern.slf4j.Slf4j;

 @Slf4j
 public class TreeMapUtil {

     public static void main(String[] args) {
         TreeMapUtil.testTreeMap("camera01,camera02,camera03");
     }

     @SuppressWarnings({ "unchecked", "deprecation" })
     public static void testTreeMap(String cameraStrList) {
         String[] splitCameraList = cameraStrList.split(",");
         LinkedList<Object> linkedList = new LinkedList<>();
         @SuppressWarnings({ "unchecked", "unused", "rawtypes" })
         TreeMap treeMap = new TreeMap(new Comparator() {
             @Override
             public int compare(Object o1, Object o2) {
                 return 0;
             }
         });
         for(String splitCamera : splitCameraList) {
             treeMap.put("cameraId", splitCamera);
         }
         linkedList.add(treeMap);
         HashMap<Object, Object> paramMap = new HashMap<>();
         paramMap.put("camera_id_list", linkedList);
         paramMap.put("callback", "http://www.baidu.com");
         log.info("linkedList: "+linkedList);
         log.info("paramMap: "+paramMap);
     }
 }

执行结果：

linkedList: [{cameraId=camera01, cameraId=camera02, cameraId=camera03}]
paramMap: {camera_id_list=[{cameraId=camera01, cameraId=camera02, cameraId=camera03}], callback=http://www.baidu.com}