研究
AutoMapper源码前,我们先来看一下
AutoMapper的作用
官网解释：AutoMapper是一个简单的小程序库，旨在解决看似复杂的问题-摆脱将一个对象映射到另一个对象的代码 解释
首先一个简单的使用AutoMapper方法演示
ar config = new MapperConfiguration(cfg =>
cfg.CreateMap<ModelObject, ModelDto>()
);
var mapper1 = config.CreateMapper();
var mode;= mapper1.Map<ModelObject>(new ModelDto{ Name= 1 });
构造函数
在这段代码中默认创建MapperConfiguration对象,并且传入一个带有映射关系的Action
当MapperConfiguration创建时,会默认执行构造函数
public MapperConfiguration(MapperConfigurationExpression configurationExpression)
{
_mappers = configurationExpression.Mappers.ToArray();
_resolvedMaps = new LockingConcurrentDictionary<TypePair, TypeMap>(GetTypeMap);
_executionPlans = new LockingConcurrentDictionary<MapRequest, Delegate>(CompileExecutionPlan);
_validator = new ConfigurationValidator(this, configurationExpression);
ExpressionBuilder = new ExpressionBuilder(this);
ServiceCtor = configurationExpression.ServiceCtor;
EnableNullPropagationForQueryMapping = configurationExpression.EnableNullPropagationForQueryMapping ?? false;
MaxExecutionPlanDepth = configurationExpression.Advanced.MaxExecutionPlanDepth + 1;
ResultConverters = configurationExpression.Advanced.QueryableResultConverters.ToArray();
Binders = configurationExpression.Advanced.QueryableBinders.ToArray();
RecursiveQueriesMaxDepth = configurationExpression.Advanced.RecursiveQueriesMaxDepth;
Configuration = new ProfileMap(configurationExpression);
Profiles = new[] { Configuration }.Concat(configurationExpression.Profiles.Select(p => new ProfileMap(p, configurationExpression))).ToArray();
configurationExpression.Features.Configure(this);
foreach (var beforeSealAction in configurationExpression.Advanced.BeforeSealActions)
beforeSealAction?.Invoke(this);
Seal();
}
在构造函数中实际就是将构建一个MapperConfigurationExpression表达式,然后将当前方法生成Action进行对象的映射,
表达式创建完成之后就进入到AutoMapper核心方法Seal方法
首先我们简单的看一下Seal方法
private void Seal()
{
var derivedMaps = new List<Tuple<TypePair, TypeMap>>();
var redirectedTypes = new List<Tuple<TypePair, TypePair>>();
//获取所有的需要映射的集合 进行注册
foreach (var profile in Profiles)
{
//单个进行注册,传入当前对象
profile.Register(this);
}
//IncludeAllDerivedTypes 子类型
foreach (var typeMap in _configuredMaps.Values.Where(tm => tm.IncludeAllDerivedTypes))
{
//循环遍历获取可以赋值的派生类型
foreach (var derivedMap in _configuredMaps
.Where(tm =>
typeMap.SourceType.IsAssignableFrom(tm.Key.SourceType) &&
typeMap.DestinationType.IsAssignableFrom(tm.Key.DestinationType) &&
typeMap != tm.Value)
.Select(tm => tm.Value))
{
//获取派生类型
typeMap.IncludeDerivedTypes(derivedMap.SourceType, derivedMap.DestinationType);
}
}
foreach (var profile in Profiles)
{
profile.Configure(this);
}
foreach (var typeMap in _configuredMaps.Values)
{
_resolvedMaps[typeMap.Types] = typeMap;
if (typeMap.DestinationTypeOverride != null)
{
redirectedTypes.Add(Tuple.Create(typeMap.Types, new TypePair(typeMap.SourceType, typeMap.DestinationTypeOverride)));
}
derivedMaps.AddRange(GetDerivedTypeMaps(typeMap).Select(derivedMap => Tuple.Create(new TypePair(derivedMap.SourceType, typeMap.DestinationType), derivedMap)));
}
foreach (var redirectedType in redirectedTypes)
{
var derivedMap = FindTypeMapFor(redirectedType.Item2);
if (derivedMap != null)
{
_resolvedMaps[redirectedType.Item1] = derivedMap;
}
}
foreach (var derivedMap in derivedMaps.Where(derivedMap => !_resolvedMaps.ContainsKey(derivedMap.Item1)))
{
_resolvedMaps[derivedMap.Item1] = derivedMap.Item2;
}
foreach (var typeMap in _configuredMaps.Values)
{
typeMap.Seal(this);
}
Features.Seal(this);
}
在这里首先会获取source Type和destination Type的字段映射对象,然后将实现过IProfiles的方法获取到,并且进行注册(添加Mapper关系)
注册
private void BuildTypeMap(IConfigurationProvider configurationProvider, ITypeMapConfiguration config)
{
//创建类型映射对象
//config.SourceType 需要转化的实体
//config.DestinationType 被映射的实体
// config.IsReverseMap 是否需要反向映射实体
var typeMap = TypeMapFactory.CreateTypeMap(config.SourceType, config.DestinationType, this, config.IsReverseMap);
config.Configure(typeMap);
configurationProvider.RegisterTypeMap(typeMap);
}
注册过程就是将需要被转化的实体和被映射的实体注册进TypeMap,最终添加MapperConfigurationExpression表达式中
注册完成之后就是获取到所有的派生类型进行注册
MapperConfigurationExpression表达式
解析
