1、ConcurrentHashMap类:调用ConcurrentHashMap()构造函数,创建cMap对象
1、ConcurrentHashMap类:调用ConcurrentHashMap(int initialCapacity),创建对象cMap,并指定初始化容量参数
1、ConcurrentHashMap类:调用ConcurrentHashMap(int initialCapacity, float loadFactor),创建cMap对象，指定容量,加载因子
1、ConcurrentHashMap类:调用ConcurrentHashMap(int initialCapacity, float loadFactor, int concurrencyLevel),创建cMap对象,指定容量,加载因子，同时加载线程数
1、ConcurrentHashMap类:调用ConcurrentHashMap(Map<? extends K,? extends V> m),创建cMap对象
