src/org/nutz/lang/util/NutMap.java
public long longDecrement(String key, long number) {
        long val = getLong(key, 0);
        val -= number;
        setv(key, val);
        return val;
    }
public long longDecrement(String key, long number) {
        long val = getLong(key, 0);
        val -= number;
        setv(key, val);
        return val;
    }
指定key进行减操作，并返回结果

@param key
键
@param number
数值
@return 减后结果