主要思想:
- 两个不同的类进行映射
- 利用for循环找到相同的属性
- 利用表达式把属性的赋值过程给存下来生成 表达式list
- 真正使用的时候, 只需要读取表达式list进行赋值就好
namespace Common
{
using NLog;
using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
public static class Mapper
where TSource : class
where TDestination : class, new()
{
private static readonly ILogger Logger = LogManager.GetCurrentClassLogger();
private static readonly Type[] NotReferenceType = new Type[] { typeof(Google.Protobuf.WellKnownTypes.Timestamp) };
public readonly static Func MapperFunc = GetMapperFunc();
public readonly static Action MapperAction = GetMapperAction();
public static TDestination MapTo(TSource source, Action action = null)
{
if (source == null)
{
Logger.Warn("The parameter ('source') cannot be null.");
return null;
}
var target = MapperFunc(source);
action?.Invoke(source, target);
return target;
}
public static List MapToList(IEnumerable sources, Action action = null)
{
if (sources == null)
{
Logger.Error($"The parameter ('sources') cannot be null.");
throw new ArgumentNullException($"The parameter('sources') cannot be null.");
}
var list = new List();
foreach (var item in sources)
{
list.Add(MapTo(item, action));
}
return list;
}
#region Private Method
private static Func GetMapperFunc()
{
return source =>
{
var target = new TDestination();
MapperAction(source, target);
return target;
};
}
private static Action GetMapperAction()
{
//获取源类型和指向类型
var sourceType = typeof(TSource);
var destinationType = typeof(TDestination);
//创建Expression参数
var sourceParameter = Expression.Parameter(sourceType, "x");
var destinationParameter = Expression.Parameter(destinationType, "p");
//创建Expression集合
var expressionList = new List();
//获取TDestination中的所有允许写入权限的Public属性 或 RepeatedField 属性
var destinationProperties = destinationType.GetProperties()
.Where(x => (x.PropertyType.IsPublic || x.PropertyType.IsNestedPublic)
&& (x.CanWrite || x.PropertyType.FullName.Contains(typeof(Google.Protobuf.Collections.RepeatedField<>).FullName)));
var sourceProperties = sourceType.GetProperties()
.Where(x => x.PropertyType.IsPublic || x.PropertyType.IsNestedPublic);
foreach (var destinationPropertyInfo in destinationProperties)
{
try
{
//获取匹配的TSource Property
var sourcePropertyInfo = sourceProperties.FirstOrDefault(x => string.Compare(x.Name, destinationPropertyInfo.Name) == 0);
if (sourcePropertyInfo == null || !sourcePropertyInfo.CanRead || sourcePropertyInfo.PropertyType.IsNotPublic)
{
continue;
}
//创建访问属性的表达式
var sourceProperty = Expression.Property(sourceParameter, sourcePropertyInfo);
var destinationProperty = Expression.Property(destinationParameter, destinationPropertyInfo);
//TSource Property不是值类型，并且和TDestination Property不相同
if (!sourcePropertyInfo.PropertyType.IsValueType
&& !NotReferenceType.Contains(sourcePropertyInfo.PropertyType)
&& sourcePropertyInfo.PropertyType != destinationPropertyInfo.PropertyType
&& sourcePropertyInfo.PropertyType != typeof(string)
&& destinationPropertyInfo.PropertyType != typeof(string))
{
//TSource Property和TDestination Property都是Class
if (sourcePropertyInfo.PropertyType.IsClass && destinationPropertyInfo.PropertyType.IsClass
&& !sourcePropertyInfo.PropertyType.IsArray && !destinationPropertyInfo.PropertyType.IsArray
&& !sourcePropertyInfo.PropertyType.IsGenericType && !destinationPropertyInfo.PropertyType.IsGenericType)
{
var expression = GetClassExpression(sourceProperty, sourcePropertyInfo.PropertyType, destinationPropertyInfo.PropertyType);
expressionList.Add(Expression.Assign(destinationProperty, expression));
continue;
}
//TSource派生自IEnumerable，TDestination类型为RepeatedField
//从C#IEnumerable转到Google ProtoBuffers RepeatedField
if (typeof(IEnumerable).IsAssignableFrom(sourcePropertyInfo.PropertyType)
&& destinationPropertyInfo.PropertyType.FullName.Contains(typeof(Google.Protobuf.Collections.RepeatedField<>).FullName))
{
var test = Expression.NotEqual(sourceProperty, Expression.Constant(null, sourcePropertyInfo.PropertyType));
//获取List泛型参数
var sourceArgument = sourcePropertyInfo.PropertyType.IsArray
? sourcePropertyInfo.PropertyType.GetElementType()
: sourcePropertyInfo.PropertyType.GetGenericArguments()[0];
var destinationArgument = sourcePropertyInfo.PropertyType.IsArray
? destinationPropertyInfo.PropertyType.GetElementType()
: destinationPropertyInfo.PropertyType.GetGenericArguments()[0];
//构建方法主体
var mapperType = typeof(Mapper<,>).MakeGenericType(sourceArgument, destinationArgument);
var actionType = typeof(Action<,>).MakeGenericType(sourceArgument, destinationArgument);
var methodCall = Expression.Call(mapperType.GetMethod(nameof(MapToList)
, new Type[] { sourcePropertyInfo.PropertyType, actionType })
, sourceProperty
, Expression.Constant(null, actionType));
//构建p.columns.addrange(maptolist(x.columns, null))
var repeatedFieldType = typeof(Google.Protobuf.Collections.RepeatedField<>)
.MakeGenericType(destinationArgument);
var callExpression = Expression.Call(
destinationProperty
, repeatedFieldType.GetMethod("AddRange")
, methodCall);
var exp = Expression.IfThen(test, callExpression);
expressionList.Add(exp);
continue;
}
//TSource 派生自 RepeatedField，TDestination 类型为 IEnumerable
//从 Google ProtoBuffers RepeatedField 转到 C#IEnumerable
if (sourcePropertyInfo.PropertyType.FullName.Contains(typeof(Google.Protobuf.Collections.RepeatedField<>).FullName)
&& typeof(IEnumerable).IsAssignableFrom(destinationPropertyInfo.PropertyType))
{
var test = Expression.NotEqual(sourceProperty, Expression.Constant(null, sourcePropertyInfo.PropertyType));
//获取List泛型参数
var sourceArgument = destinationPropertyInfo.PropertyType.IsArray
? sourcePropertyInfo.PropertyType.GetElementType()
: sourcePropertyInfo.PropertyType.GetGenericArguments()[0];
var destinationArgument = destinationPropertyInfo.PropertyType.IsArray
? destinationPropertyInfo.PropertyType.GetElementType()
: destinationPropertyInfo.PropertyType.GetGenericArguments()[0];
//构建方法主体
var mapperType = typeof(Mapper<,>).MakeGenericType(sourceArgument, destinationArgument);
var actionType = typeof(Action<,>).MakeGenericType(sourceArgument, destinationArgument);
var methodCall = Expression.Call(mapperType.GetMethod(nameof(MapToList)
, new Type[] { sourcePropertyInfo.PropertyType, actionType })
, sourceProperty
, Expression.Constant(null, actionType));
var result = Expression.Assign(destinationProperty, methodCall);
expressionList.Add(Expression.IfThen(test, result));
continue;
}
//TSource 和 TDestination都是直接或间接派生自IEnumerable
if (typeof(IEnumerable).IsAssignableFrom(sourcePropertyInfo.PropertyType)
&& typeof(IEnumerable).IsAssignableFrom(destinationPropertyInfo.PropertyType))
{
var expression = GetEnumerableExpression(sourceProperty, sourcePropertyInfo.PropertyType, destinationPropertyInfo.PropertyType);
expressionList.Add(Expression.Assign(destinationProperty, expression));
continue;
}
}
//可空类型转换到非可空类型，当可空类型值为null时，用默认值赋给目标属性；不为null就直接转换
else if (IsNullable(sourcePropertyInfo.PropertyType) && !IsNullable(destinationPropertyInfo.PropertyType))
{
var hasValueExpression = Expression.Equal(Expression.Property(sourceProperty, "HasValue"), Expression.Constant(true));
//C# DateTime?类型转换到ProtoBuffers TimeStamp
if (sourcePropertyInfo.PropertyType.FullName.Contains(typeof(DateTime).FullName)
&& destinationPropertyInfo.PropertyType.FullName.Contains(typeof(Google.Protobuf.WellKnownTypes.Timestamp).FullName))
{
var timestampType = typeof(Google.Protobuf.WellKnownTypes.Timestamp);
var valueExpression = Expression.Condition(hasValueExpression, Expression.Convert(sourceProperty,typeof(DateTime)), Expression.Default(typeof(DateTime)));
var callExpression = Expression.Call(valueExpression, typeof(DateTime).GetMethod("ToUniversalTime"));
var call = Expression.Call(timestampType.GetMethod("FromDateTime", new Type[] { typeof(DateTime) }), callExpression);
var conditionDateTime = Expression.Condition(hasValueExpression, call, Expression.Default(destinationPropertyInfo.PropertyType));
expressionList.Add(Expression.Assign(destinationProperty, conditionDateTime));
}
else
{
var condition = Expression.Condition(hasValueExpression, Expression.Convert(sourceProperty, destinationPropertyInfo.PropertyType), Expression.Default(destinationPropertyInfo.PropertyType));
expressionList.Add(Expression.Assign(destinationProperty, condition));
}
continue;
}
//非可空类型转换到可空类型，直接转换
else if (!IsNullable(sourcePropertyInfo.PropertyType) && IsNullable(destinationPropertyInfo.PropertyType))
{
var memberExpression = Expression.Convert(sourceProperty, destinationPropertyInfo.PropertyType);
expressionList.Add(Expression.Assign(destinationProperty, memberExpression));
continue;
}
//ProtoBuffers TimeStamp类型转换到C# DateTime类型
else if (sourcePropertyInfo.PropertyType.FullName.Contains(typeof(Google.Protobuf.WellKnownTypes.Timestamp).FullName)
&& destinationPropertyInfo.PropertyType.FullName.Contains(typeof(DateTime).FullName))
{
var timestampType = typeof(Google.Protobuf.WellKnownTypes.Timestamp);
//var callExpression = Expression.Call(timestampType, nameof(Google.Protobuf.WellKnownTypes.Timestamp.ToDateTime), new Type[] { timestampType }, sourceProperty)
var callExpression = Expression.Call(sourceProperty, timestampType.GetMethod("ToDateTime"));
expressionList.Add(Expression.Assign(destinationProperty, callExpression));
continue;
}
//C# DateTime类型转换到ProtoBuffers TimeStamp
else if (sourcePropertyInfo.PropertyType.FullName.Contains(typeof(DateTime).FullName)
&& destinationPropertyInfo.PropertyType.FullName.Contains(typeof(Google.Protobuf.WellKnownTypes.Timestamp).FullName))
{
var timestampType = typeof(Google.Protobuf.WellKnownTypes.Timestamp);
var callExpression = Expression.Call(sourceProperty, typeof(DateTime).GetMethod("ToUniversalTime"));
var call = Expression.Call(timestampType.GetMethod("FromDateTime", new Type[] { typeof(DateTime) }), callExpression);
expressionList.Add(Expression.Assign(destinationProperty, call));
continue;
}
//String 转换 Guid
else if (sourcePropertyInfo.PropertyType.FullName.Contains(typeof(string).FullName)
&& destinationPropertyInfo.PropertyType.FullName.Contains(typeof(Guid).FullName))
{
var call = Expression.Call(typeof(Guid).GetMethod("Prase", new Type[] { typeof(string) }), sourceProperty);
expressionList.Add(Expression.Assign(destinationProperty, call));
continue;
}
else if (sourcePropertyInfo.PropertyType.FullName.Contains(typeof(string).FullName)
&& destinationPropertyInfo.PropertyType.FullName.Contains(typeof(string).FullName))
{
var test = Expression.NotEqual(sourceProperty, Expression.Constant(null, sourcePropertyInfo.PropertyType));
var ifThenExp = Expression.IfThen(test, Expression.Assign(destinationProperty, sourceProperty));
expressionList.Add(ifThenExp);
continue;
}
// Enum
else if (sourcePropertyInfo.PropertyType.IsEnum && destinationPropertyInfo.PropertyType.IsEnum)
{
var convertExpression = Expression.Convert(sourceProperty, destinationPropertyInfo.PropertyType);
expressionList.Add(Expression.Assign(destinationProperty, convertExpression));
continue;
}
else if (sourcePropertyInfo.PropertyType != destinationPropertyInfo.PropertyType)
{
continue;
}
var assignExpression = Expression.Assign(destinationProperty, sourceProperty);
expressionList.Add(assignExpression);
}
catch(ArgumentNullException ex)
{
Logger.Error(ex);
throw new ArgumentNullException(ex.Message, ex);
}
catch(ArgumentException ex)
{
Logger.Error(ex);
throw new ArgumentException(ex.Message, ex);
}
catch (Exception ex)
{
Logger.Error(ex);
throw new InvalidOperationException(ex.Message, ex);
}
}
//当TDestination ！= null，判断TSource是否为null
var testSource = Expression.NotEqual(sourceParameter, Expression.Constant(null, sourceType));
var ifTrueSource = Expression.Block(expressionList);
var conditionSource = Expression.IfThen(testSource, ifTrueSource);
//判断TDestination是否为空
var testTarget = Expression.NotEqual(destinationParameter, Expression.Constant(null, destinationType));
var conditionTarget = Expression.IfThen(testTarget, conditionSource);
var lambda = Expression.Lambda>(conditionTarget, sourceParameter, destinationParameter);
return lambda.Compile();
}
private static Expression GetClassExpression(Expression sourceExpression, Type sourcePropertyType, Type destinationPropertyType)
{
try
{
var test = Expression.NotEqual(sourceExpression, Expression.Constant(null, sourcePropertyType));
//构建方法主体
var mapperManagerType = typeof(Mapper<,>).MakeGenericType(sourcePropertyType, destinationPropertyType);
var actionType = typeof(Action<,>).MakeGenericType(sourcePropertyType, destinationPropertyType);
var ifTrue = Expression.Call(mapperManagerType.GetMethod(nameof(MapTo), new Type[] { sourcePropertyType, actionType }), sourceExpression, Expression.Constant(null, actionType));
var ifFalse = Expression.Constant(null, destinationPropertyType);
var condition = Expression.Condition(test, ifTrue, ifFalse);
return condition;
}
catch (Exception ex)
{
Logger.Error(ex);
throw new ArgumentException(ex.Message, ex);
}
}
private static Expression GetEnumerableExpression(Expression sourceExpression, Type sourcePropertyType, Type destinationPropertyType)
{
try
{
var test = Expression.NotEqual(sourceExpression, Expression.Constant(null, sourcePropertyType));
//获取List泛型参数
var sourceArgument = sourcePropertyType.IsArray ? sourcePropertyType.GetElementType() : sourcePropertyType.GetGenericArguments()[0];
var destinationArgument = sourcePropertyType.IsArray ? destinationPropertyType.GetElementType() : sourcePropertyType.GetGenericArguments()[0];
//构建方法主体
var mapperManagerType = typeof(Mapper<,>).MakeGenericType(sourceArgument, destinationArgument);
var actionType = typeof(Action<,>).MakeGenericType(sourceArgument, destinationArgument);
var methodCall = Expression.Call(mapperManagerType.GetMethod(nameof(MapToList), new Type[] { sourcePropertyType, actionType }), sourceExpression, Expression.Constant(null, sourcePropertyType));
Expression ifTrue;
if (destinationPropertyType.Equals(methodCall.Type))
{
ifTrue = methodCall;
}
else if (destinationPropertyType.IsArray)
{
//数组，获取泛型TSource，调用ToArray方法转化
ifTrue = Expression.Call(typeof(Enumerable), nameof(Enumerable.ToArray), new[] { methodCall.Type.GenericTypeArguments[0] }, methodCall);
}
else if (typeof(IDictionary).IsAssignableFrom(destinationPropertyType))
{
//字典，获取泛型TSource，调用ToDictionary方法转化
ifTrue = Expression.Call(typeof(Enumerable), nameof(Enumerable.ToDictionary), new[] { methodCall.Type.GenericTypeArguments[0] }, methodCall);
}
else
{
ifTrue = Expression.Convert(methodCall, destinationPropertyType);
}
var ifFlase = Expression.Constant(null, destinationPropertyType);
var conditionItem = Expression.Condition(test, ifTrue, ifFlase);
return conditionItem;
}
catch (Exception ex)
{
Logger.Error(ex);
throw new ArgumentException(ex.Message, ex);
}
}
private static bool IsNullable(Type type)
{
return type.IsGenericType && type.GetGenericTypeDefinition().Equals(typeof(Nullable<>));
}
#endregion
}
}
