java.math.BigInteger cannot be cast to java.lang.Long异常

问题：java.math.BigInteger cannot be cast to java.lang.Long异常

解决方法：mysql中统计出的结果是BigInteger，要是强制类型转换为Long报java.math.BigInteger cannot be cast to java.lang.Long异常。如果查出的结果是count，则转为Long型用count.longValue();