//設(shè)置Redis最大占用內(nèi)存大小為100Mmaxmemory 100mb            

                
//設(shè)置Redis最大占用內(nèi)存大小為100M127.0.0.1:6379> config set maxmemory 100mb//獲取設(shè)置的Redis能使用的最大內(nèi)存大小127.0.0.1:6379> config get maxmemory            

                
127.0.0.1:6379> config get maxmemory-policy            

                
maxmemory-policy allkeys-lru            

                
127.0.0.1:6379> config set maxmemory-policy allkeys-lru            

                
public class LRUCache {    //容量    private int capacity;    //當(dāng)前有多少節(jié)點(diǎn)的統(tǒng)計(jì)    private int count;    //緩存節(jié)點(diǎn)    private Map> nodeMap;    private Node head;    private Node tail;
    public LRUCache(int capacity) {        if (capacity < 1) {            throw new IllegalArgumentException(String.valueOf(capacity));        }        this.capacity = capacity;        this.nodeMap = new HashMap<>();        //初始化頭節(jié)點(diǎn)和尾節(jié)點(diǎn)，利用哨兵模式減少判斷頭結(jié)點(diǎn)和尾節(jié)點(diǎn)為空的代碼        Node headNode = new Node(null, null);        Node tailNode = new Node(null, null);        headNode.next = tailNode;        tailNode.pre = headNode;        this.head = headNode;        this.tail = tailNode;    }
    public void put(k key, v value) {        Node node = nodeMap.get(key);        if (node == null) {            if (count >= capacity) {                //先移除一個(gè)節(jié)點(diǎn)                removeNode();            }            node = new Node<>(key, value);            //添加節(jié)點(diǎn)            addNode(node);        } else {            //移動(dòng)節(jié)點(diǎn)到頭節(jié)點(diǎn)            moveNodeToHead(node);        }    }
    public Node get(k key) {        Node node = nodeMap.get(key);        if (node != null) {            moveNodeToHead(node);        }        return node;    }
    private void removeNode() {        Node node = tail.pre;        //從鏈表里面移除        removeFromList(node);        nodeMap.remove(node.key);        count--;    }
    private void removeFromList(Node node) {        Node pre = node.pre;        Node next = node.next;
        pre.next = next;        next.pre = pre;
        node.next = null;        node.pre = null;    }
    private void addNode(Node node) {        //添加節(jié)點(diǎn)到頭部        addToHead(node);        nodeMap.put(node.key, node);        count++;    }
    private void addToHead(Node node) {        Node next = head.next;        next.pre = node;        node.next = next;        node.pre = head;        head.next = node;    }
    public void moveNodeToHead(Node node) {        //從鏈表里面移除        removeFromList(node);        //添加節(jié)點(diǎn)到頭部        addToHead(node);    }
    class Node {        k key;        v value;        Node pre;        Node next;
        public Node(k key, v value) {            this.key = key;            this.value = value;        }    }}