Automapper编译映射

我们在ASP.NET Core 2.0中使用了者 .

我们想创建一次映射配置，将从每个映射器使用 . 我们为每个请求创建一个mapper，我们不会遇到问题，因为我读过一次automapper不是线程安全的 .

我们喜欢在应用程序启动时预编译映射配置（参见Code MapperConfigruation.CompileMappings（）;

如果我测量映射所花费的时间，我会看到第一个映射比其他映射需要更多的时间 . 是有原因还是我有bug？

Code

In ConfigureService of Startup class:

services.AddSingleton<MyMapperConfiguration>();
 services.AddScoped<IObjectMapper, MyMapper>();

Mapperconfiguration

public class MyMapperConfiguration
    {
        public MapperConfiguration MapperConfiguration { get; private set; }

        public MappingDefinition MappingDefinition { get; }

        public MapperConfiguration(IOptions<MappingDefinition> mappings)
        {
            // MappingDefinitions hold some information where to search mappings  
            MappingDefinition = mappings.Value;
        }


        public void Configure()
        {
            List<Type> mappingDefinitionClasses = new List<Type>();

             // Search Types with special attribute and add it to the typelist

            MapperConfiguration = new MapperConfiguration(cfg =>
            {
                cfg.AddProfiles(mappingDefinitionClasses.ToArray());
            });            
            MapperConfiguration.CompileMappings(); // <-- THIS SHOULD COMPILE THE MAPPING I THNIK?!

        }

`

Mapper

public class MyMapper : IObjectMapper
    {      
        public IMapper Mapper { get; }

        public Mapper(MapperConfiguration mappingConfiguration)
        {           
            Mapper = mappingConfiguration.MapperConfiguration.CreateMapper();
        }

        public TDestination Map<TSource, TDestination>(TSource source)
        {
            return Mapper.Map<TSource, TDestination>(source);
        }
    }

IObjectMapper:

public interface IObjectMapper
    {        
        TDestination Map<TSource, TDestination>(TSource source);        
    }

Measure time inside a webApi

Stopwatch sw = new Stopwatch();
sw.Start();
destObj = _mapper.Map<Source, Destination>(sourceObj);
sw.Stop();
Debug.WriteLine($"Duration of mapping: {sw.ElapsedMilliseconds}");

在Startup的Configruate方法中，我还获得了映射配置的实例，并调用此实例生效的Configure（） .