• AutoMapper之ABP项目中的使用介绍


    最近在研究ABP项目,昨天写了Castle Windsor常用介绍以及其在ABP项目的应用介绍 欢迎各位拍砖,有关ABP的介绍请看阳光铭睿 博客

    AutoMapper只要用来数据转换,在园里已经有很多这方面文章了,本文主要介绍其在实际项目常用总结,以及在ABP项目中的应用介绍。AutoMapper应用非常简单,大家稍微看下文档就可以上手,但是性能不好啊,所以一般用在后台项目,对外的项目千万不要用。就那NOP来说吧,它也是把AutoMapper放在后台项目使用,商城前台的项目是不敢用的。

    有关性能的问题本文没有涉及到,想了解的请参考EmitMapper,AutoMapper,NLiteMapper和手工映射性能大比拼 和 NLiteMapper与EmitMapper性能简单比较

    下面主要讲下项目的入门和项目中的使用。

    AutoMapper使用只要两步,配置和Mapper,一般的在项目中我们会在Global中进行配置

    配置映射关系

    public class Source
    {
       public int SomeValue { get; set; }
    }
    
    public class Destination
    {
       public int SomeValue { get; set; }
    }
    
    //这个就是配置映射关系
    Mapper.CreateMap<Source, Destination>();
    

    然后就是Mapper

    Source source = new Source()
    {
        SomeValue = 1
    };
    
    var destination = Mapper.Map<Source, Destination>(source);
    Console.WriteLine(destination.SomeValue);//1
    

    是不是很简单,这是最简单的使用了,当然AutoMapper是个“机关枪”,这个只是它的最简单使用。下面在介绍几点常用的功能。还是上面那个例子,只是字段变了

        public class Source
        {
            public int SomeValue { get; set; }
        }
    
        public class Destination
        {
            public int SomeValuefff { get; set; }
        }
    
        Mapper.CreateMap<AddressDto, Address>();
    

    这样子字段都不一样明细是不能映射的嘛,所有呢我们可以用Mapper.AssertConfigurationIsValid()来验证,就会AutoMapperConfigurationException异常,

    选择忽略相关字段

    Mapper.CreateMap<Source, Destination>()
            .ForMember(dest => dest.SomeValuefff, opt => opt.Ignore());
    

    类型转换,自定义类型转换

        public class Source
        {
            public string Value1 { get; set; }
            public string Value2 { get; set; }
            public string Value3 { get; set; }
        }
    
        public class Destination
        {
            public int Value1 { get; set; }
            public DateTime Value2 { get; set; }
            public Type Value3 { get; set; }
        }
    

    Source要转Destination,但是第二和第三的字段类型都不一致,所以我们可以自定义类型转换,下面看下转换函数ConvertUsing一般最常用第二种,接受一个ITypeConverter

        void ConvertUsing(Func<TSource, TDestination> mappingFunction);
        void ConvertUsing(ITypeConverter<TSource, TDestination> converter);
        void ConvertUsing<TTypeConverter>() where TTypeConverter : ITypeConverter<TSource, TDestination>;

    下面看下ITypeConverter接口

        public interface ITypeConverter<TSource, TDestination>
        {
            TDestination Convert(ResolutionContext context);
        }
    

    我们可以继承这个接口队Convert进行重写

        public class DateTimeTypeConverter : ITypeConverter<string, DateTime>
        {
            public DateTime Convert(ResolutionContext context)
            {
                return System.Convert.ToDateTime(context.SourceValue);
            }
        }
    
        public class TypeTypeConverter : ITypeConverter<string, Type>
        {
            public Type Convert(ResolutionContext context)
            {
                  return context.SourceType;
            }
        }
    

    这样我们就可以映射了,下面看下完整代码

        public void Example()
        {
            Mapper.CreateMap<string, int>().ConvertUsing(Convert.ToInt32);
            Mapper.CreateMap<string, DateTime>().ConvertUsing(new DateTimeTypeConverter());
            Mapper.CreateMap<string, Type>().ConvertUsing<TypeTypeConverter>();
            Mapper.CreateMap<Source, Destination>();
            Mapper.AssertConfigurationIsValid();
    
            var source = new Source
            {
                Value1 = "5",
                Value2 = "01/01/2000",
                Value3 = "AutoMapperSamples.GlobalTypeConverters.GlobalTypeConverters+Destination"
            };
    
            Destination result = Mapper.Map<Source, Destination>(source);
            result.Value3.ShouldEqual(typeof (Destination));
        }
    
        public class DateTimeTypeConverter : ITypeConverter<string, DateTime>
        {
            public DateTime Convert(ResolutionContext context)
            {
                return System.Convert.ToDateTime(context.SourceValue);
            }
        }
    
        public class TypeTypeConverter : ITypeConverter<string, Type>
        {
            public Type Convert(ResolutionContext context)
            {
                  return context.SourceType;
            }
        }
    

    好了,上面把 AutoMapper在项目中常用的方法都介绍完了,再介绍ABP之前我们先看下NOP是怎么使用的吧,由于代码较长省略部分

        public class AutoMapperStartupTask : IStartupTask
        {
            public void Execute()
            {
                //TODO remove 'CreatedOnUtc' ignore mappings because now presentation layer models have 'CreatedOn' property and core entities have 'CreatedOnUtc' property (distinct names)
                
                //address
                Mapper.CreateMap<Address, AddressModel>()
                    .ForMember(dest => dest.AddressHtml, mo => mo.Ignore())
                    .ForMember(dest => dest.CustomAddressAttributes, mo => mo.Ignore())
                    .ForMember(dest => dest.FormattedCustomAddressAttributes, mo => mo.Ignore())
                    .ForMember(dest => dest.AvailableCountries, mo => mo.Ignore())
                    .ForMember(dest => dest.AvailableStates, mo => mo.Ignore())
                    .ForMember(dest => dest.FirstNameEnabled, mo => mo.Ignore())
                    .ForMember(dest => dest.FirstNameRequired, mo => mo.Ignore())
                    .ForMember(dest => dest.LastNameEnabled, mo => mo.Ignore())
                    .ForMember(dest => dest.LastNameRequired, mo => mo.Ignore())
                    .ForMember(dest => dest.EmailEnabled, mo => mo.Ignore())
                    .ForMember(dest => dest.EmailRequired, mo => mo.Ignore())
                    .ForMember(dest => dest.CompanyEnabled, mo => mo.Ignore())
                    .ForMember(dest => dest.CompanyRequired, mo => mo.Ignore())
                    .ForMember(dest => dest.CountryEnabled, mo => mo.Ignore())
                    .ForMember(dest => dest.StateProvinceEnabled, mo => mo.Ignore())
    ...
    

    好了,终于可以到ABP的了,ABP对AutoMapper的使用总结出来两点,1、在模块中初始化配置,2、遍历bin目录下所有的Types判断哪些类是否被定义为需要转换的Attribute

    在模块中初始化配置

        public class AbpAutoMapperModule : AbpModule
        {
            private readonly ITypeFinder _typeFinder;
    
            private static bool _createdMappingsBefore;
            private static readonly object _syncObj = new object();
            
            public AbpAutoMapperModule(ITypeFinder typeFinder)
            {
                _typeFinder = typeFinder;
            }
    
            private void FindAndAutoMapTypes()
            {
                var types = _typeFinder.Find(type =>
                    type.IsDefined(typeof(AutoMapAttribute)) ||
                    type.IsDefined(typeof(AutoMapFromAttribute)) ||
                    type.IsDefined(typeof(AutoMapToAttribute))
                    );
    
                foreach (var type in types)
                {
                    AutoMapperHelper.CreateMap(type);
                }
            }
        }
    

    AbpAutoMapperModule 模块会在Global的时候被初始化,然后在PreInitialize的时候回调用到FindAndAutoMapTypes,有关模块是怎么初始化的我想再写一篇介绍。下面我们看下_typeFinder吧

    上面_typeFinder.Find调用的是TypeFinder的Find方法

            public Type[] Find(Func<Type, bool> predicate)
            {
                return GetAllTypes().Where(predicate).ToArray();
            }
    
            public Type[] FindAll()
            {
                return GetAllTypes().ToArray();
            }
    
            private List<Type> GetAllTypes()
            {
                var allTypes = new List<Type>();
    
                foreach (var assembly in AssemblyFinder.GetAllAssemblies().Distinct())
                {
                    try
                    {
                        Type[] typesInThisAssembly;
    
                        try
                        {
                            typesInThisAssembly = assembly.GetTypes();
                        }
                        catch (ReflectionTypeLoadException ex)
                        {
                            typesInThisAssembly = ex.Types;
                        }
    
                        if (typesInThisAssembly.IsNullOrEmpty())
                        {
                            continue;
                        }
    
                        allTypes.AddRange(typesInThisAssembly.Where(type => type != null));
                    }
                    catch (Exception ex)
                    {
                        Logger.Warn(ex.ToString(), ex);
                    }
                }
    
                return allTypes;
            }
    

    好吧,上面代码有点多,但是很简单,就是获取所有的Types,我们看下关键代码AssemblyFinder.GetAllAssemblies()

        public class WebAssemblyFinder : IAssemblyFinder
        {
            /// <summary>
            /// This return all assemblies in bin folder of the web application.
            /// </summary>
            /// <returns>List of assemblies</returns>
            public List<Assembly> GetAllAssemblies()
            {
                var assembliesInBinFolder = new List<Assembly>();
    
                var allReferencedAssemblies = BuildManager.GetReferencedAssemblies().Cast<Assembly>().ToList();
                var dllFiles = Directory.GetFiles(HttpRuntime.AppDomainAppPath + "bin\", "*.dll", SearchOption.TopDirectoryOnly).ToList();
    
                foreach (string dllFile in dllFiles)
                {
                    var locatedAssembly = allReferencedAssemblies.FirstOrDefault(asm => AssemblyName.ReferenceMatchesDefinition(asm.GetName(), AssemblyName.GetAssemblyName(dllFile)));
                    if (locatedAssembly != null)
                    {
                        assembliesInBinFolder.Add(locatedAssembly);
                    }
                }
    
                return assembliesInBinFolder;
            }
        }
    

    看看吧,这代码是或bin目录下面的dll,好丧心病狂啊,回到刚刚AbpAutoMapperModule 的获取FindAndAutoMapTypes方法。在获取所有的Types之后我们就要判断这个类是否是被标识了

    AutoMapAttribute、AutoMapFromAttribute和AutoMapToAttribute

            private void FindAndAutoMapTypes()
            {
                var types = _typeFinder.Find(type =>
                    type.IsDefined(typeof(AutoMapAttribute)) ||
                    type.IsDefined(typeof(AutoMapFromAttribute)) ||
                    type.IsDefined(typeof(AutoMapToAttribute))
                    );
    
                foreach (var type in types)
                {
                    AutoMapperHelper.CreateMap(type);
                }
            }
    

    获取之后再我下的Demo中就只有一个UserDto类被标识了 

    namespace AbpDemo.Application.Users.Dto
    {
        [AutoMapFrom(typeof(User))]
        public class UserDto : EntityDto<long>
        {
            public string UserName { get; set; }
    
            public string Name { get; set; }
            
            public string Surname { get; set; }
            
            public string EmailAddress { get; set; }
        }
    }
    

    接下来就是遍历所有的types进行配置了AutoMapperHelper.CreateMap(type);配置也很简单 看下代码

            public static void CreateMap<TAttribute>(Type type)
                where TAttribute : AutoMapAttribute
            {
                if (!type.IsDefined(typeof (TAttribute)))
                {
                    return;
                }
    
                foreach (var autoMapToAttribute in type.GetCustomAttributes<TAttribute>())
                {
                    if (autoMapToAttribute.TargetTypes.IsNullOrEmpty())
                    {
                        continue;
                    }
    
                    foreach (var targetType in autoMapToAttribute.TargetTypes)
                    {
                        if (autoMapToAttribute.Direction.HasFlag(AutoMapDirection.To))
                        {
                            Mapper.CreateMap(type, targetType);
                        }
    
                        if (autoMapToAttribute.Direction.HasFlag(AutoMapDirection.From))
                        {
                            Mapper.CreateMap(targetType, type);                                
                        }
                    }
                }
            }
    

    好了,表达能力不是很好,各位就勉强看下吧。终于写完了。发现作者很喜欢用Attribute来过滤。这边AutoMapper是这样,UnitOfWork也是这样,其实这样也是挺方便的,有点AOP的切面的感觉,值得学习。 

    参考文章:

    http://www.cnblogs.com/netcasewqs/archive/2011/04/13/2014684.html

    http://www.cnblogs.com/repository/archive/2011/04/08/2009713.html

    https://github.com/AutoMapper/AutoMapper/wiki/Configuration-validation

    http://www.cnblogs.com/youring2/p/automapper.html

    http://www.cnblogs.com/1-2-3/p/AutoMapper-Best-Practice.html

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  • 原文地址:https://www.cnblogs.com/huaizuo/p/4835289.html
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