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本篇文章為大家展示了Redis中怎么實(shí)現(xiàn)LRU緩存機(jī)制,內(nèi)容簡明扼要并且容易理解,絕對能使你眼前一亮,通過這篇文章的詳細(xì)介紹希望你能有所收獲。
第一種實(shí)現(xiàn)(使用LinkedHashMap)
public class LRUCache {int capacity; Map<Integer,Integer> map;public LRUCache(int capacity){this.capacity = capacity; map = new LinkedHashMap<>(); }public int get(int key){//如果沒有找到if (!map.containsKey(key)){return -1; }//找到了就刷新數(shù)據(jù)Integer value = map.remove(key); map.put(key,value);return value; }public void put(int key,int value){if (map.containsKey(key)){ map.remove(key); map.put(key,value);return; } map.put(key,value);//超出capacity,刪除最久沒用的即第一個(gè),或者可以復(fù)寫removeEldestEntry方法if (map.size() > capacity){ map.remove(map.entrySet().iterator().next().getKey()); } }public static void main(String[] args) { LRUCache lruCache = new LRUCache(10);for (int i = 0; i < 10; i++) { lruCache.map.put(i,i); System.out.println(lruCache.map.size()); } System.out.println(lruCache.map); lruCache.put(10,200); System.out.println(lruCache.map); }
public class LRUCache { private int capacity; private Map<Integer,ListNode>map; private ListNode head; private ListNode tail; public LRUCache2(int capacity){ this.capacity = capacity;map = new HashMap<>(); head = new ListNode(-1,-1); tail = new ListNode(-1,-1); head.next = tail; tail.pre = head; } public int get(int key){if (!map.containsKey(key)){return -1; } ListNode node = map.get(key);node.pre.next = node.next;node.next.pre = node.pre;return node.val; } public void put(int key,int value){if (get(key)!=-1){map.get(key).val = value;return; } ListNode node = new ListNode(key,value);map.put(key,node); moveToTail(node);if (map.size() > capacity){map.remove(head.next.key); head.next = head.next.next; head.next.pre = head; } } //把節(jié)點(diǎn)移動(dòng)到尾巴 private void moveToTail(ListNode node) {node.pre = tail.pre; tail.pre = node;node.pre.next = node;node.next = tail; } //定義雙向鏈表節(jié)點(diǎn) private class ListNode{ int key; int val; ListNode pre; ListNode next; //初始化雙向鏈表 public ListNode(int key,int val){ this.key = key; this.val = val; pre = null;next = null; } } }
像第一種方式,如果復(fù)寫removeEldestEntry會(huì)更簡單,這里簡單的展示一下
public class LRUCache extends LinkedHashMap<Integer,Integer> {private int capacity; @Overrideprotected boolean removeEldestEntry(Map.Entry<Integer, Integer> eldest) {return size() > capacity; } }
上述內(nèi)容就是Redis中怎么實(shí)現(xiàn)LRU緩存機(jī)制,你們學(xué)到知識或技能了嗎?如果還想學(xué)到更多技能或者豐富自己的知識儲備,歡迎關(guān)注億速云行業(yè)資訊頻道。
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