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
