方法一：
using Newtonsoft.Json.Linq;
using System;
using System.Collections.Generic;
using System.Linq;JObject testJson = new JObject()
{{ "code", "1234560" },{ "app", null }
};
testJson.DescendantsAndSelf().OfType<JProperty>().Where(p => p.Value.Type == JTokenType.Null || p.Value.ToString() == "").ToList().ForEach(p => p.Remove());
方法二：
直接调用方法即可
private static void RemoveEmptyValues(JToken token)
{if (token is JValue){if (token.Type == JTokenType.Null || (token.Type == JTokenType.String && token.ToString() == "")){token.Parent.Remove();}}else if (token is JContainer){foreach (JToken child in token.Children().ToList()){RemoveEmptyValues(child);}if (!token.HasValues){token.Parent.Remove();}}
}
方法三：
直接调用方法即可
public static JToken RemoveEmptyValues(JToken token)
{if (token.Type == JTokenType.Object){JObject obj = (JObject)token;List<string> keysToRemove = new List<string>();foreach (JProperty prop in obj.Properties()){JToken propValue = RemoveEmptyValues(prop.Value);if (propValue.Type == JTokenType.Null ||propValue.Type == JTokenType.String && ((string)propValue).Trim() == "" ||propValue.Type == JTokenType.Array && !propValue.HasValues ||propValue.Type == JTokenType.Object && !((JObject)propValue).HasValues){keysToRemove.Add(prop.Name);}else{prop.Value = propValue;}}foreach (string key in keysToRemove){obj.Remove(key);}return obj;}else if (token.Type == JTokenType.Array){JArray arr = (JArray)token;List<JToken> itemsToRemove = new List<JToken>();for (int i = 0; i < arr.Count; i++){JToken item = RemoveEmptyValues(arr[i]);if (item.Type == JTokenType.Null ||item.Type == JTokenType.String && ((string)item).Trim() == "" ||item.Type == JTokenType.Array && !item.HasValues ||item.Type == JTokenType.Object && !((JObject)item).HasValues){itemsToRemove.Add(arr[i]);}else{arr[i] = item;}}foreach (JToken item in itemsToRemove){arr.Remove(item);//item.RemoveFromLowestPossibleParent();}return arr;}// 对于其他类型的JToken（如原始值），直接返回原始tokenreturn token;
}
方法四：
仅针对于有对应实体类的JSON序列化
public class Person
{public string Name { get; set; }public int? Age { get; set; }
}static void Main(string[] args)
{Person person = new Person(){Name = "Test",Age = null};var setting = new JsonSerializerSettings{NullValueHandling = NullValueHandling.Ignore};string str = JsonConvert.SerializeObject(person, setting);
}
