C#高级：常用的扩展方法大全

1.String

public static class StringExtensions
{/// <summary>/// 字符串转List（中逗 英逗分隔）/// </summary>public static List<string> SplitCommaToList(this string data){if (string.IsNullOrEmpty(data)){return new List<string>();}data = data.Replace("，", ",");//中文逗号转化为英文return data.Split(",").ToList();}/// <summary>/// 字典按序替换字符串（用key代替value）/// </summary>/// <returns></returns>public static string DictionaryReplace(this string input, Dictionary<string, string> replacements){if (string.IsNullOrEmpty(input) || replacements == null || replacements.Count == 0){return input;}foreach (var replacement in replacements){input = input.Replace(replacement.Value, replacement.Key);//用key代替value}return input;}/// <summary>/// 反序列化成实体/// </summary>public static T ConvertToEntity<T>(this string json)//可传入列表，实体{return JsonSerializer.Deserialize<T>(json);}}

2.DateTime

3.List

public static class ListExtensions
{/// <summary>/// 例如输入1 3 输出第1个（含）到第3个（含）的实体列表/// </summary>public static List<T> GetRangeList<T>(this List<T> list, int startIndex, int endIndex){// 检查索引范围是否有效if (startIndex < 1 || endIndex > list.Count || startIndex > endIndex){//throw new ArgumentOutOfRangeException("输入的索引值超出了列表的长度或范围不正确！");return new List<T>();}// 返回指定范围内的元素return list.GetRange(startIndex - 1, endIndex - startIndex + 1);}/// <summary>/// 传入列表和需要获取的数量，返回随机选出的元素/// </summary>/// <returns></returns>public static List<T> GetRandomList<T>(this List<T> list, int count){// 检查列表是否足够if (list.Count < count){//throw new ArgumentException("列表中的元素不足，无法随机选择所需数量的元素。");return new List<T>();}// 使用 Random 类生成随机索引Random random = new Random();// 随机选择不重复的元素return list.OrderBy(x => random.Next()).Take(count).ToList();}/// <summary>/// 按指定字段，顺序排序，且返回xx条/// </summary>/// <returns></returns>public static List<V> OrderByAndTake<T, V>(this List<V> list, Expression<Func<V, T>> keySelector, int count){if (list == null || !list.Any() || count <= 0){return new List<V>();}var sortedlist = list.OrderBy(keySelector.Compile());return sortedlist.Take(count).ToList();}/// <summary>/// 按指定字段，倒序排序，且返回xx条/// </summary>/// <returns></returns>public static List<V> OrderByDescAndTake<T, V>(this List<V> list, Expression<Func<V, T>> keySelector, int count){if (list == null || !list.Any() || count <= 0){return new List<V>();}var sortedlist = list.OrderByDescending(keySelector.Compile());return sortedlist.Take(count).ToList();}/// <summary>/// 传入列表，返回一个元组（索引，列表实体）/// </summary>/// <returns></returns>public static List<(int index , T entity)> GetIndexList<T>(this List<T> list){List<(int index, T entity)> result = new List<(int index, T entity)>();for (int i = 0; i < list.Count; i++){result.Add((i, list[i]));}return result;}/// <summary>/// 列表为null或空列表则返回True/// </summary>/// <returns></returns>public static bool IsNullOrEmpty<T>(this List<T> list){return list == null || !list.Any();}/// <summary>/// 一个实体列表映射到另一个实体列表（属性名称相同则映射）/// </summary>public static List<TTarget> MapToList<TTarget>(this IEnumerable<object> sourceList) where TTarget : new(){var targetList = new List<TTarget>();foreach (var source in sourceList){var target = new TTarget();var sourceProperties = source.GetType().GetProperties(); // 使用实际对象的类型var targetProperties = typeof(TTarget).GetProperties();foreach (var sourceProp in sourceProperties){var targetProp = targetProperties.FirstOrDefault(tp => tp.Name == sourceProp.Name && tp.CanWrite);if (targetProp != null && targetProp.PropertyType == sourceProp.PropertyType){targetProp.SetValue(target, sourceProp.GetValue(source));}}targetList.Add(target);}return targetList;}/// <summary>/// 列表转JSON（string）/// </summary>/// <returns></returns>public static string ConvertToJson<T>(this List<T> sourceList)//可传入列表，实体{var options = new JsonSerializerOptions{Encoder = JavaScriptEncoder.UnsafeRelaxedJsonEscaping // 禁用 Unicode 转义，防止中文字符转义为 Unicode};return JsonSerializer.Serialize(sourceList, options);}}

4.Entity

public static class EntityExtensions
{/// <summary>/// 实体转JSON/// </summary>public static string ConvertToJson<T>(T entity)//可传入列表，实体{var options = new JsonSerializerOptions{Encoder = JavaScriptEncoder.UnsafeRelaxedJsonEscaping // 禁用 Unicode 转义，防止中文字符转义为 Unicode};return JsonSerializer.Serialize(entity, options);}/// <summary>/// 将一个实体映射到另一个实体（属性名称相同且类型匹配的属性将映射）/// </summary>public static TTarget MapToEntity<TTarget>(this object source) where TTarget : new(){var target = new TTarget();var sourceProperties = source.GetType().GetProperties(); // 获取源实体的属性var targetProperties = typeof(TTarget).GetProperties(); // 获取目标实体的属性foreach (var sourceProp in sourceProperties){var targetProp = targetProperties.FirstOrDefault(tp => tp.Name == sourceProp.Name && tp.CanWrite);if (targetProp != null && targetProp.PropertyType == sourceProp.PropertyType){targetProp.SetValue(target, sourceProp.GetValue(source));}}return target;}/// <summary>/// 通过反射设置实体的值/// </summary>/// <typeparam name="T"></typeparam>/// <returns></returns>public static void SetValueByReflect<T>(this T entity, string feildName, object feildValue) where T : class{var feild = typeof(T).GetProperty(feildName);var feildType = feild?.PropertyType;if (feild != null && feildType != null){var valueToSet = Convert.ChangeType(feildValue, feildType);//输入的值类型转化为实体属性的类型feild.SetValue(entity, valueToSet);}}
}