需求背景:对象复制性能优化;同时,在对象复制时,应跳过引用类型的null值复制,值类型支持值类型向可空类型的复制
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using Common; using System; class Program { static void Main( string [] args) { TestClassA classA = new TestClassA() { PropA = new TestClass() { Name = "cs1" }, PropB = "c1" , PropC = 1 }; TestClassA classB = new TestClassA() { PropA = new TestClass() { Name = "cs2" }, PropB = "c2" , PropC = 2 }; FastCopy.Copy(classA, classB, false ); Console.WriteLine(classB.PropA?.Name + ":" + classB.PropB + ":" + classB.PropC); TestClassA classC = new TestClassA() { PropA = new TestClass() { Name = "cs1" } }; TestClassA classD = new TestClassA() { PropA = new TestClass() { Name = "cs2" }, PropB = "c2" , PropC = 2 }; FastCopy.Copy(classC, classD, false ); Console.WriteLine(classD.PropA?.Name + ":" + classD.PropB + ":" + classD.PropC); } } public class TestClassA { public TestClass PropA { get ; set ; } public string PropB { get ; set ; } public int ? PropC { get ; set ; } } public class TestClass { public string Name { get ; set ; } } |
输出:
百万次调用耗时:270-300ms
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using System; using System.Collections.Concurrent; using System.Collections.Generic; using System.Linq; using System.Linq.Expressions; using System.Reflection; using static System.Linq.Expressions.Expression; namespace Common { public static class FastCopy { static ConcurrentDictionary< string , object > copiers = new ConcurrentDictionary< string , object >(); /// <summary> /// 复制两个对象同名属性值 /// </summary> /// <typeparam name="S"></typeparam> /// <typeparam name="T"></typeparam> /// <param name="source">源对象</param> /// <param name="target">目标对象</param> /// <param name="copyNull">源对象属性值为null时,是否将值复制给目标对象</param> public static void Copy<S, T>(S source, T target, bool copyNull = true ) { string name = string .Format( "{0}_{1}_{2}" , typeof (S), typeof (T), copyNull); object targetCopier; if (!copiers.TryGetValue(name, out targetCopier)) { Action<S, T> copier = CreateCopier<S, T>(copyNull); copiers.TryAdd(name, copier); targetCopier = copier; } Action<S, T> action = (Action<S, T>)targetCopier; action(source, target); } /// <summary> /// 为指定的两种类型编译生成属性复制委托 /// </summary> /// <typeparam name="S"></typeparam> /// <typeparam name="T"></typeparam> /// <param name="copyNull">源对象属性值为null时,是否将值复制给目标对象</param> /// <returns></returns> private static Action<S, T> CreateCopier<S, T>( bool copyNull) { ParameterExpression source = Parameter( typeof (S)); ParameterExpression target = Parameter( typeof (T)); var sourceProps = typeof (S).GetProperties(BindingFlags.Instance | BindingFlags.Public).Where(p => p.CanRead).ToList(); var targetProps = typeof (T).GetProperties(BindingFlags.Instance | BindingFlags.Public).Where(p => p.CanWrite).ToList(); // 查找可进行赋值的属性 var copyProps = targetProps.Where(tProp => sourceProps.Where(sProp => sProp.Name == tProp.Name // 名称一致 且 && ( sProp.PropertyType == tProp.PropertyType // 属性类型一致 或 || sProp.PropertyType.IsAssignableFrom(tProp.PropertyType) // 源属性类型 为 目标属性类型 的 子类;eg:object target = string source; 或 || (tProp.PropertyType.IsValueType && sProp.PropertyType.IsValueType && // 属性为值类型且基础类型一致,但目标属性为可空类型 eg:int? num = int num; ((tProp.PropertyType.GenericTypeArguments.Length > 0 ? tProp.PropertyType.GenericTypeArguments[0] : tProp.PropertyType) == sProp.PropertyType)) )).Count() > 0); List<Expression> expressionList = new List<Expression>(); foreach (var prop in copyProps) { if (prop.PropertyType.IsValueType) // 属性为值类型 { PropertyInfo sProp = typeof (S).GetProperty(prop.Name); PropertyInfo tProp = typeof (T).GetProperty(prop.Name); if (sProp.PropertyType == tProp.PropertyType) // 属性类型一致 eg:int num = int num; 或 int? num = int? num; { var assign = Assign(Property(target, prop.Name), Property(source, prop.Name)); expressionList.Add(assign); } else if (sProp.PropertyType.GenericTypeArguments.Length <= 0 && tProp.PropertyType.GenericTypeArguments.Length > 0) // 属性类型不一致且目标属性类型为可空类型 eg:int? num = int num; { var convert = Convert(Expression.Property(source, prop.Name), tProp.PropertyType); var cvAssign = Assign(Expression.Property(target, prop.Name), convert); expressionList.Add(cvAssign); } } else // 属性为引用类型 { var assign = Assign(Property(target, prop.Name), Property(source, prop.Name)); // 编译生成属性赋值语句 target.{PropertyName} = source.{PropertyName}; var sourcePropIsNull = Equal(Constant( null , prop.PropertyType), Property(source, prop.Name)); // 判断源属性值是否为Null;编译生成 source.{PropertyName} == null var setNull = IsTrue(Constant(copyNull)); // 判断是否复制Null值 编译生成 copyNull == True var setNullTest = IfThen(setNull, assign); var condition = IfThenElse(sourcePropIsNull, setNullTest, assign); /** * 编译生成 * if(source.{PropertyName} == null) * { * if(setNull) * { * target.{PropertyName} = source.{PropertyName}; * } * } * else * { * target.{PropertyName} = source.{PropertyName}; * } */ expressionList.Add(condition); } } var block = Block(expressionList.ToArray()); Expression<Action<S, T>> lambda = Lambda<Action<S, T>>(block, source, target); return lambda.Compile(); } } } |
如果完整复制,去掉逻辑判断,同时可通过泛型类,不在使用字典,性能还可以提升。
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using System; using System.Linq; using System.Linq.Expressions; using System.Reflection; namespace Common { public static class FastCopy<S, T> { static Action<S, T> action = CreateCopier(); /// <summary> /// 复制两个对象同名属性值 /// </summary> /// <typeparam name="S"></typeparam> /// <typeparam name="T"></typeparam> /// <param name="source">源对象</param> /// <param name="target">目标对象</param> /// <param name="copyNull">源对象属性值为null时,是否将值复制给目标对象</param> public static void Copy(S source, T target, bool copyNull = true ) { action(source, target); } /// <summary> /// 为指定的两种类型编译生成属性复制委托 /// </summary> /// <typeparam name="S"></typeparam> /// <typeparam name="T"></typeparam> /// <param name="copyNull">源对象属性值为null时,是否将值复制给目标对象</param> /// <returns></returns> private static Action<S, T> CreateCopier() { ParameterExpression source = Expression.Parameter( typeof (S)); ParameterExpression target = Expression.Parameter( typeof (T)); var sourceProps = typeof (S).GetProperties(BindingFlags.Instance | BindingFlags.Public).Where(p => p.CanRead).ToList(); var targetProps = typeof (T).GetProperties(BindingFlags.Instance | BindingFlags.Public).Where(p => p.CanWrite).ToList(); // 查找可进行赋值的属性 var copyProps = targetProps.Where(tProp => sourceProps.Where(sProp => sProp.Name == tProp.Name // 名称一致 且 && ( sProp.PropertyType == tProp.PropertyType // 属性类型一致 )).Count() > 0); var block = Expression.Block(from p in copyProps select Expression.Assign(Expression.Property(target, p.Name), Expression.Property(source, p.Name))); Expression<Action<S, T>> lambda = Expression.Lambda<Action<S, T>>(block, source, target); return lambda.Compile(); } } } |
百万次耗时:100ms左右
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原文链接:https://www.cnblogs.com/mq0036/p/15762333.html