fix listener bug

hutool-core/src/main/java/cn/hutool/core/cache/impl/LRUCache.java

@@ -1,5 +1,6 @@
 package cn.hutool.core.cache.impl;
 
+import cn.hutool.core.lang.mutable.Mutable;
 import cn.hutool.core.map.FixedLinkedHashMap;
 
 import java.util.Iterator;
@@ -42,7 +43,13 @@ public class LRUCache<K, V> extends ReentrantCache<K, V> {
 		this.timeout = timeout;
 
 		//链表key按照访问顺序排序，调用get方法后，会将这次访问的元素移至头部
-		cacheMap = new FixedLinkedHashMap<>(capacity);
+		final FixedLinkedHashMap<Mutable<K>, CacheObj<K, V>> fixedLinkedHashMap = new FixedLinkedHashMap<>(capacity);
+		fixedLinkedHashMap.setRemoveListener(entry -> {
+			if(null != listener){
+				listener.onRemove(entry.getKey().get(), entry.getValue().getValue());
+			}
+		});
+		cacheMap = fixedLinkedHashMap;
 	}
 
 	// ---------------------------------------------------------------- prune

hutool-core/src/main/java/cn/hutool/core/map/FixedLinkedHashMap.java

@@ -1,21 +1,28 @@
 package cn.hutool.core.map;
 
 import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.function.Consumer;
 
 /**
  * 固定大小的{@link LinkedHashMap} 实现<br>
  * 注意此类非线程安全，由于{@link #get(Object)}操作会修改链表的顺序结构，因此也不可以使用读写锁。
  *
- * @author looly
- *
  * @param <K> 键类型
  * @param <V> 值类型
+ * @author looly
  */
 public class FixedLinkedHashMap<K, V> extends LinkedHashMap<K, V> {
 	private static final long serialVersionUID = -629171177321416095L;
 
-	/** 容量，超过此容量自动删除末尾元素 */
+	/**
+	 * 容量，超过此容量自动删除末尾元素
+	 */
 	private int capacity;
+	/**
+	 * 移除监听
+	 */
+	private Consumer<java.util.Map.Entry<K, V>> removeListener;
 
 	/**
 	 * 构造
@@ -45,10 +52,25 @@ public class FixedLinkedHashMap<K, V> extends LinkedHashMap<K, V> {
 		this.capacity = capacity;
 	}
 
+	/**
+	 * 设置自定义移除监听
+	 *
+	 * @param removeListener 移除监听
+	 */
+	public void setRemoveListener(final Consumer<Map.Entry<K, V>> removeListener) {
+		this.removeListener = removeListener;
+	}
+
 	@Override
 	protected boolean removeEldestEntry(final java.util.Map.Entry<K, V> eldest) {
 		//当链表元素大于容量时，移除最老（最久未被使用）的元素
-		return size() > this.capacity;
+		if (size() > this.capacity) {
+			if (null != removeListener) {
+				// 自定义监听
+				removeListener.accept(eldest);
+			}
+			return true;
+		}
+		return false;
 	}
-
 }

hutool-core/src/test/java/cn/hutool/core/cache/LRUCacheTest.java

@@ -1,6 +1,8 @@
 package cn.hutool.core.cache;
 
 import cn.hutool.core.cache.impl.LRUCache;
+import cn.hutool.core.lang.Console;
+import cn.hutool.core.text.StrUtil;
 import cn.hutool.core.thread.ThreadUtil;
 import cn.hutool.core.util.RandomUtil;
 import org.junit.Assert;
@@ -64,4 +66,16 @@ public class LRUCacheTest {
 		}
 		Assert.assertEquals("null123456789", sb2.toString());
 	}
+
+	@Test
+	public void issue2647Test(){
+		final LRUCache<String, Integer> cache = CacheUtil.newLRUCache(3,1);
+		cache.setListener((key, value) -> Console.log("Start remove k-v, key:{}, value:{}", key, value));
+
+		for (int i = 0; i < 10; i++) {
+			cache.put(StrUtil.format("key-{}", i), i);
+		}
+
+		Assert.assertEquals(3, cache.size());
+	}
 }