C#基础：使用Linq进行简单去重处理（DinstinctBy/反射）

目录

一、示例代码

二、示例输出

三、注意雷点

四、全字段去重封装方法

1.封装

2.示例

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一、示例代码 using System; using System.Collections.Generic; using System.Linq; public class Program { public static void Main() { // 创建一些示例实体对象 var people = new List<Person> { new Person { Name = "Alice", Age = 30, City = "New York" }, new Person { Name = "Bob", Age = 25, City = "Los Angeles" }, new Person { Name = "Alice", Age = 30, City = "New York" },//重复的 new Person { Name = "Charlie", Age = 35, City = "Chicago" }, new Person { Name = "Alice", Age = 28, City = "San Francisco" } }; // 1. 单字段去重 var uniqueNameFields = people.DistinctBy(p =>p.Name).ToList(); Console.WriteLine("指定字段（Name）去重结果,重复则保留第一条:"); foreach (var person in uniqueNameFields) { Console.WriteLine($"Name: {person.Name}, Age: {person.Age}, City: {person.City}"); } // 2. 多字段去重 var uniqueNameAgeFields = people.DistinctBy(p => new { p.Name, p.Age }).ToList(); Console.WriteLine("\n指定字段（Name, Age）去重结果,重复则保留第一条:"); foreach (var person in uniqueNameAgeFields) { Console.WriteLine($"Name: {person.Name}, Age: {person.Age}, City: {person.City}"); } //3.全字段去重 // 通过 GroupBy 按 Name 和 Age 字段去重 var uniquePeople = people.DistinctBy(p => new { p.Name, p.Age, p.City }).ToList(); Console.WriteLine("\n全字段去重:"); foreach (var person in uniquePeople) { Console.WriteLine($"Name: {person.Name}, Age: {person.Age}, City: {person.City}"); } } } public class Person { public string Name { get; set; } public int Age { get; set; } public string City { get; set; } } 二、示例输出 指定字段（Name）去重结果,重复则保留第一条: Name: Alice, Age: 30, City: New York Name: Bob, Age: 25, City: Los Angeles Name: Charlie, Age: 35, City: Chicago 指定字段（Name, Age）去重结果,重复则保留第一条: Name: Alice, Age: 30, City: New York Name: Bob, Age: 25, City: Los Angeles Name: Charlie, Age: 35, City: Chicago Name: Alice, Age: 28, City: San Francisco 全字段去重: Name: Alice, Age: 30, City: New York Name: Bob, Age: 25, City: Los Angeles Name: Charlie, Age: 35, City: Chicago Name: Alice, Age: 28, City: San Francisco 三、注意雷点

        以下代码不能完成全字段去重，因为people是引用类型，Distinct() 一般用于List<string>,List<int>这些值类型去重，而不涉及引用类型的字段比较。

people.Distinct().ToList()

        若需要全字段去重：1.使用DinstinctBy语法，加上所有字段。2.使用标题四的封装方法（反射实现全字段去重）。

四、全字段去重封装方法 1.封装 /// <summary> /// 通用的全字段去重方法 /// </summary> /// <returns></returns> public static IEnumerable<T> DistinctByAllFields<T>(IEnumerable<T> items) { // 获取 T 类型的所有字段值 var properties = typeof(T).GetProperties(BindingFlags.Public | BindingFlags.Instance); return items .GroupBy(item => string.Join(",", properties.Select(p => p.GetValue(item)))) // 按所有字段值连接生成唯一标识符 .Select(group => group.First()); // 取每组的第一个元素 } 2.示例 using System; using System.Collections.Generic; using System.Linq; using System.Reflection; public class Program { public static void Main() { // 创建一些示例实体对象 var people = new List<Person> { new Person { Name = "Alice", Age = 30, City = "New York" }, new Person { Name = "Bob", Age = 25, City = "Los Angeles" }, new Person { Name = "Alice", Age = 30, City = "New York" }, new Person { Name = "Charlie", Age = 35, City = "Chicago" }, new Person { Name = "Alice", Age = 28, City = "San Francisco" } }; // 调用封装的去重方法 var uniquePeople = DistinctByAllFields(people).ToList(); Console.WriteLine("根据所有字段去重的结果:"); foreach (var person in uniquePeople) { Console.WriteLine($"Name: {person.Name}, Age: {person.Age}, City: {person.City}"); } } /// <summary> /// 通用的全字段去重方法 /// </summary> /// <returns></returns> public static IEnumerable<T> DistinctByAllFields<T>(IEnumerable<T> items) { // 获取 T 类型的所有字段值 var properties = typeof(T).GetProperties(BindingFlags.Public | BindingFlags.Instance); return items .GroupBy(item => string.Join(",", properties.Select(p => p.GetValue(item)))) // 按所有字段值连接生成唯一标识符 .Select(group => group.First()); // 取每组的第一个元素 } } public class Person { public string Name { get; set; } public int Age { get; set; } public string City { get; set; } }