c# reflection traverses all fields of entities, detailed introduction to the implementation of ObjectDumper class

When recording logs, sometimes you need to know the value of each field of an entity. In this case, you need to use reflection to traverse the members and return them as a string. If the member is still a custom type, it needs to be executed recursively.

Implementation method:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Reflection;
using System.Collections;


namespace ServerToolServer.Util
{
    public class ObjectDumper
    {
        /// <summary>
        /// 本次记录最大的字节数
        /// </summary>
        private static int MAXLENGTH = 16384;


        /// <summary>
        /// 当前要记录的对象
        /// </summary>
        private static object lastObj = null;


        /// <summary>
        /// 反射出obj的字段名和字段值
        /// </summary>
        /// <typeparam name="T">要反射的类型</typeparam>
        /// <param name="obj">实体</param>
        /// <returns>字段名：字段值</returns>
        public static string GetObjStr(object obj)
        {
            if (obj == null)
            {
                return "";
            }


            StringBuilder ret = new StringBuilder(30);
            FieldInfo[] fields = obj.GetType().GetFields();
            if (fields == null || fields.Length == 0)
            {
                return ret.ToString();
            }
            else
            {
                foreach (FieldInfo eachField in fields)
                {
                    GetObjStr(obj, eachField, ret);
                }
            }
        
            return ret.ToString();


        }


        /// <summary>
        /// 反射出对象的字段名：值
        /// </summary>
        /// <param name="entity">要反射的对象</param>
        /// <param name="obj">字段</param>
        /// <param name="str">记录的stringbuilder</param>
        public static void GetObjStr(object entity, object obj, StringBuilder str)
        {
            try
            {


                ////避免无限递归，确保一个对象只会被记录一次
                if (Object.ReferenceEquals(obj, lastObj))
                {
                    return;
                }
                lastObj = obj;




                if (entity == null || obj == null)
                {
                    return;
                }


                if (str.Length > MAXLENGTH)
                {
                    str.Append("...to long...");
                    return;
                }


                FieldInfo f = obj as FieldInfo;
                string typeName = f == null ? obj.GetType().Name : f.Name;
                Type type = f == null ? obj.GetType() : f.FieldType;
                object value = f == null ? obj : f.GetValue(entity);


                if (type.IsValueType || type == typeof(string))
                {
                    if (str.Length > MAXLENGTH)
                    {
                        str.Append("...to long...");
                        return;
                    }
                    str.Append(typeName);
                    str.Append(" : ");
                    str.Append(value);
                    str.Append("\r\n");
                    return;
                }




                ////如果成员是个集合，递归遍历
                if (typeof(IEnumerable).IsAssignableFrom(type))
                {
                    IEnumerable ie = value as IEnumerable;
                    if (ie != null)
                    {
                        IEnumerator list = ie.GetEnumerator();
                        while (list.MoveNext())
                        {
                            ////基本数据类型或者string
                            if (list.Current.GetType().IsValueType || list.Current.GetType() == typeof(string))
                            {
                                if (str.Length > MAXLENGTH)
                                {
                                    str.Append("...to long...");
                                    return;
                                }
                                else
                                {
                                    str.Append(type);
                                    str.Append(" : ");
                                    str.Append(list.Current);
                                    str.Append("\r\n");
                                }
                            }


                            ////自定义类型
                            else
                            {
                                str.Append(list.Current.GetType());
                                str.Append(".");
                                FieldInfo[] fields = list.Current.GetType().GetFields();
                                foreach (FieldInfo subField in fields)
                                {


                                    if (str.Length > MAXLENGTH)
                                    {
                                        str.Append("...to long...");
                                        return;
                                    }
                                    GetObjStr(list.Current, subField, str);
                                }


                            }
                        }
                    }
                }


                else
                {
                    str.Append(type);
                    str.Append(".");
                    FieldInfo[] fields = type.GetFields();
                    if (fields.Length == 0)
                    {
                        return;
                    }
                    foreach (FieldInfo subField in fields)
                    {


                        if (str.Length > MAXLENGTH)
                        {
                            str.Append("...to long...");
                            return;
                        }
                        GetObjStr(value, subField, str);
                    }


                }
            }
            catch (Exception ex)
            {
                return;
            }
        }
    }
}

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