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C#高级：通过一个遍历实体的小案例去理解反射（基础版）

news 来源：原创 2024/9/20 22:45:11

一、任务一二：遍历、获取、设置字段的值（手到擒来）

二、任务三：获取指定类型的字段名称（绝群拔类）

三、任务四：通过反射打印列表（反客为主）

**一、任务一二：遍历、获取、设置字段的值（手到擒来）**

任务一：获取实体的所有字段，输出字段名、字段类型、字段值

任务二：获取实体的指定字段，输出该字段值、赋值该字段值

（field是属性，stu是带有数据的实体）

【不封装实现】

using ConsoleApp1;
using SqlSugar;
using System.Reflection;class Program
{public class Student{public int id { get; set; }public string name { get; set; }public int age { get; set; }}static void Main(){Student stu = new Student { id = 1, name = "小苏", age = 18 };//任务一：遍历打印这个实体的字段名，字段类型，字段的值foreach (var field in typeof(Student).GetProperties()){Console.Write($"field Name: {field.Name}, ");Console.Write($"Type: {field.PropertyType.Name}, ");Console.WriteLine($"Value: {field.GetValue(stu)}");}//任务二：获取stu的age字段，将age的字段值设置为20//获取到Age属性var field = typeof(Student).GetProperties().First(x=>x.Name=="age");//通过属性反射给实体赋值field.SetValue(stu, 20);//查看赋值后的结果var resultage = field.GetValue(stu);Console.WriteLine(resultage);;}
}

任务一：获取实体的所有字段，输出字段名、字段类型、字段值

任务二：获取实体的指定字段，输出该字段值、赋值该字段值

（field都是属性，stu是带有数据的实体）

【小封装实现-更好理解】

using ConsoleApp1;
using SqlSugar;
using System.Reflection;class Program
{public class Student{public int id { get; set; }public string name { get; set; }public int age { get; set; }}/// <summary>/// 获取实体的所有属性/// </summary>/// <typeparam name="T"></typeparam>/// <returns></returns>static PropertyInfo[] GetEntity<T>() where T : class{return typeof(T).GetProperties();}/// <summary>/// 获取实体的某个属性/// </summary>/// <typeparam name="T"></typeparam>/// <param name="Fieldname"></param>/// <returns></returns>static PropertyInfo GetField<T>(string Fieldname) where T : class{return typeof(T).GetProperties().First(x => x.Name == Fieldname);}static void Main(){Student stu = new Student { id = 1, name = "小苏", age = 18 };//任务一：遍历打印这个实体的字段名，字段类型，字段的值foreach (var field in GetEntity<Student>()){Console.Write($"field Name: {field.Name}, ");Console.Write($"Type: {field.PropertyType.Name}, ");Console.WriteLine($"Value: {field.GetValue(stu)}");}//任务二：获取stu的age字段，将age的字段值设置为20//获取到Age属性var field = GetField<Student>("age");//通过属性反射给实体赋值field.SetValue(stu, 20);//查看赋值后的结果var resultage = field.GetValue(stu);Console.WriteLine(resultage);//20}
}

（封装代码）

    /// <summary>/// 获取实体的所有属性（属性列表）/// </summary>/// <typeparam name="T"></typeparam>/// <returns></returns>static PropertyInfo[] GetEntity<T>() where T : class{return typeof(T).GetProperties();}/// <summary>/// 获取实体的某个属性（单个属性）/// </summary>/// <typeparam name="T"></typeparam>/// <param name="Fieldname"></param>/// <returns></returns>static PropertyInfo GetField<T>(string Fieldname) where T : class{return typeof(T).GetProperties().First(x => x.Name == Fieldname);}

二、任务三：获取指定类型的字段名称（绝群拔类）

【封装的方法】

using ConsoleApp1;
using SqlSugar;
using System.Reflection;class Program
{public class Student{public int id { get; set; }public string name { get; set; }public int age { get; set; }}/// <summary>/// 获取实体的所有属性/// </summary>/// <typeparam name="T"></typeparam>/// <returns></returns>static PropertyInfo[] GetEntity<T>() where T : class{return typeof(T).GetProperties();}static List<string> GetintField<T>(T entity) where T : class{List<string> result = new List<string>();foreach (var item in GetEntity<T>()){if (item.PropertyType==typeof(int)){result.Add(item.Name);}}return result;}static List<string> GetintField2<T>() where T : class{List<string> result = new List<string>();foreach (var item in GetEntity<T>()){if (item.PropertyType == typeof(int)){result.Add(item.Name);}}return result;}static void Main(){Student stu = new Student { id = 1, name = "小苏", age = 18 };//任务三：获取指定类型(例如int类型)的字段名称//以下两种方法都可以，只是入参不一样var result = GetintField(stu);var result2 = GetintField2<Student>();//输出id,age}
}

三、任务四：通过反射打印列表（反客为主）

【实现代码】

using ConsoleApp1;
using SqlSugar;
using System.Reflection;class Program
{public class Student{public int id { get; set; }public string name { get; set; }public int age { get; set; }}/// <summary>/// 获取实体的所有属性/// </summary>/// <typeparam name="T"></typeparam>/// <returns></returns>static PropertyInfo[] GetEntity<T>() where T : class{return typeof(T).GetProperties();}/// <summary>/// 通过反射获取实体的某个属性/// </summary>/// <typeparam name="T"></typeparam>/// <param name="entity"></param>/// <param name="index"></param>/// <returns></returns>static object? ReflexGetValue<T>(T entity,int index) where  T : class{return GetEntity<T>()[index].GetValue(entity);}static void Main(){List<Student> stulist = new List<Student> { new Student { id = 1, name = "小苏", age = 18 }, new Student { id = 2, name = "小明", age = 17 }, new Student { id = 3, name = "小虹", age = 19 } };//任务四：通过反射遍历打印实体列表（反客为主）Console.WriteLine("----------直接打印-----------");foreach (var item in stulist){Console.WriteLine(item.id);Console.WriteLine(item.name);Console.WriteLine(item.age);}Console.WriteLine("-----------反射1-------------");foreach (var item in stulist){Console.WriteLine(ReflexGetValue(item,0));Console.WriteLine(ReflexGetValue(item, 1));Console.WriteLine(ReflexGetValue(item, 2));}Console.WriteLine("-----------反射2-------------");foreach (var item in stulist){for (var i = 0; i < GetEntity<Student>().Length; i++){Console.WriteLine(ReflexGetValue(item, i));}}/*打印效果（都一样）：1小苏182小明173小虹19        */}
}

【封装方法】

    /// <summary>/// 获取实体的所有属性/// </summary>/// <typeparam name="T"></typeparam>/// <returns></returns>static PropertyInfo[] GetEntity<T>() where T : class{return typeof(T).GetProperties();}/// <summary>/// 通过反射获取实体的某个属性/// </summary>/// <typeparam name="T"></typeparam>/// <param name="entity"></param>/// <param name="index"></param>/// <returns></returns>static object? ReflexGetValue<T>(T entity,int index) where  T : class{return GetEntity<T>()[index].GetValue(entity);}