设计新的路由算法"LRU"；规划新算法"LFU"；

xxl-job-admin/src/main/java/com/xxl/job/admin/core/route/ExecutorRouteStrategyEnum.java

     ROUND("轮询", new ExecutorRouteRound()),
     RANDOM("随机", new ExecutorRouteRandom()),
     CONSISTENT_HASH("一致性HASH", new ExecutorRouteConsistentHash()),
+    LEAST_FREQUENTLY_USED("最不经常使用", new ExecutorRouteLFU()),
+    LEAST_RECENTLY_USED("最近最久未使用", new ExecutorRouteLRU()),
     FAILOVER("故障转移", null);
 
     ExecutorRouteStrategyEnum(String title, ExecutorRouter router) {

xxl-job-admin/src/main/java/com/xxl/job/admin/core/route/ExecutorRouter.java

 
     public static void main(String[] args) {
 
-        int c1 = 0;
-        int c2 = 0;
-        int c3 = 0;
-
-        long start = System.currentTimeMillis();
-        for (int i = 0; i < 10; i++) {
-            String ret = ExecutorRouter.route(i, new ArrayList<String>(Arrays.asList("127.0.0.1:0000", "127.0.0.1:2222", "127.0.0.1:3333")), ExecutorRouteStrategyEnum.CONSISTENT_HASH.name());
-            if (ret.equals("127.0.0.1:0000")) {
-                c1++;
-            } else if (ret.equals("127.0.0.1:2222")) {
-                c2++;
-            } else if (ret.equals("127.0.0.1:3333")) {
-                c3++;
-            }
-        }
-        long end = System.currentTimeMillis();
-        System.out.println(end - start);    // 1000*100=740、1000*1=162、
-
 
-        System.out.println(c1);
-        System.out.println(c2);
-        System.out.println(c3);
+        for (int i = 0; i < 100; i++) {
+            String ret = ExecutorRouter.route(666, new ArrayList<String>(Arrays.asList("127.0.0.1:0000", "127.0.0.1:2222", "127.0.0.1:3333")), ExecutorRouteStrategyEnum.LEAST_RECENTLY_USED.name());
+            System.out.println(ret);
+        }
 
     }
 

xxl-job-admin/src/main/java/com/xxl/job/admin/core/route/strategy/ExecutorRouteConsistentHash.java

 import java.util.TreeMap;
 
 /**
- * 分组下JOB均匀散列在不同机器上；且每个JOB固定调度其中一台机器；
+ * 分组下机器地址相同，不同JOB均匀散列在不同机器上，保证分组下机器分配JOB平均；且每个JOB固定调度其中一台机器；
  *      a、virtual node：解决不均衡问题
  *      b、hash method replace hashCode：String的hashCode可能重复，需要进一步扩大hashCode的取值范围
  * Created by xuxueli on 17/3/10.

xxl-job-admin/src/main/java/com/xxl/job/admin/core/route/strategy/ExecutorRouteLFU.java

+package com.xxl.job.admin.core.route.strategy;
+
+import com.xxl.job.admin.core.route.ExecutorRouter;
+
+import java.util.ArrayList;
+
+/**
+ * 单个JOB对应的每个执行器，使用频率最低的优先被选举
+ *      a(*)、LFU(Least Frequently Used)：最不经常使用，频率/次数
+ *      b、LRU(Least Recently Used)：最近最久未使用，时间
+ *
+ * Created by xuxueli on 17/3/10.
+ */
+public class ExecutorRouteLFU extends ExecutorRouter {
+
+    @Override
+    public String route(int jobId, ArrayList<String> addressList) {
+
+        // TODO
+
+        return addressList.get(0);
+    }
+
+}

xxl-job-admin/src/main/java/com/xxl/job/admin/core/route/strategy/ExecutorRouteLRU.java

+package com.xxl.job.admin.core.route.strategy;
+
+import com.xxl.job.admin.core.route.ExecutorRouter;
+
+import java.util.ArrayList;
+import java.util.LinkedHashMap;
+import java.util.concurrent.ConcurrentHashMap;
+
+/**
+ * 单个JOB对应的每个执行器，最久为使用的优先被选举
+ *      a、LFU(Least Frequently Used)：最不经常使用，频率/次数
+ *      b(*)、LRU(Least Recently Used)：最近最久未使用，时间
+ *
+ * Created by xuxueli on 17/3/10.
+ */
+public class ExecutorRouteLRU extends ExecutorRouter {
+
+    private static ConcurrentHashMap<Integer, LinkedHashMap<String, String>> jobLRUMap = new ConcurrentHashMap<Integer, LinkedHashMap<String, String>>();
+
+    @Override
+    public String route(int jobId, ArrayList<String> addressList) {
+
+        LinkedHashMap<String, String> lruItem = jobLRUMap.get(jobId);
+        if (lruItem == null) {
+            /**
+             * LinkedHashMap
+             *      a、accessOrder：ture=访问顺序排序（get/put时排序）；false=插入顺序排期；
+             *      b、removeEldestEntry：新增元素时将会调用，返回true时会删除最老元素；可封装LinkedHashMap并重写该方法，比如定义最大容量，超出是返回true即可实现固定长度的LRU算法；
+             */
+            lruItem = new LinkedHashMap<>(16, 0.75f, true);
+            jobLRUMap.put(jobId, lruItem);
+        }
+
+        for (String address: addressList) {
+            if (!lruItem.containsKey(address)) {
+                lruItem.put(address, address);
+            }
+        }
+
+        String eldestKey = lruItem.entrySet().iterator().next().getKey();
+        String eldestValue = lruItem.get(eldestKey);
+        return eldestValue;
+    }
+
+}