keySet遍历key+value
for (String key : map.keySet()) { value = map.get(key); }
遍历key
for (String key : map.keySet()) { }
遍历value
for (String value : map.values()) { }
for (String key : map.keySet()) { value = map.get(key); }
for (String key : map.keySet()) { }
for (String value : map.values()) { }