报错信息：
InvalidOperationException: Unable to resolve service for type 'AutoMapper.Mapper'
while attempting to activate 'BLL.Implementation.Report'.
检查后发现名称写错了
错误：
private readonly Mapper _mapper;
正确的是：
private readonly IMapper _mapper;
另外一种情况是没有在startup类的ConfigureServices中注入automapper依赖
先在Nuget里下载AutoMapper 之后再startup文件引用，最后注入依赖
