//采用数组 + 链表结构,再对数组元素采用分段锁
//数组
final Segment<K,V>[] segments;
//数组元素
static final class Segment<K,V> extends ReentrantLock implements Serializable {
transient volatile HashEntry<K,V>[] table;
}
//链表
static final class HashEntry<K,V> {
final int hash;
final K key;
volatile V value;
volatile HashEntry<K,V> next;
}
//构造方法里concurrencyLevel是Segment[]数组的长度,initialCapacity(CurrentHashMap的容量)是所有HashEntry数组的长度总和,
//即每个Segment对象里面的HashEntry数组长度为initialCapacity/concurrencyLevel
//initialCapacity和concurrencyLevel默认值是16,loadFactor默认值是0.75
public ConcurrentHashMap(int initialCapacity, float loadFactor, int concurrencyLevel) {}
//CurrentHashMap put元素
//1.先获取key哈希值,然后根据哈希值定位到Segment[]的index
//2.调用Segment.put()