1.JSONObject put方法

public Object put (Object key,Object value)

将value映射到key下。如果此JSONObject对象之前存在一个value在这个key下，当前的value会替换掉之前的value

Associates the specified value with the specified key in this map(optional operation). If the map prevIoUsly contained . a mapping for this key,the old value is replaced by the specified value. (A map m is said to contain a mapping for a key k if and only if m.containsKey(k) would return true .))