即使返回异常也返回json字符串的扩展:

        public static string OnlyValidJson(this string strInput)
        {
            if (string.IsNullOrWhiteSpace(strInput)) { return @"[""Json is empty""]"; }
            strInput = strInput.Trim();
            if ((strInput.StartsWith("{") && strInput.EndsWith("}")) ||
                (strInput.StartsWith("[") && strInput.EndsWith("]")))
            {
                try
                {
                    string strEscape = strInput.Replace("\\n", "").Replace("\\r", "").Replace("\n", "").Replace("\r", "");
                    JToken.Parse(strEscape);
                    return strEscape;
                }
                catch (JsonReaderException jex)
                {
                    return @$"{{""JsonReaderException"":""{jex.Message}""}}";
                }
                catch (Exception ex)
                {
                    Console.WriteLine(ex.ToString());
                    return @$"{{""Exception"":""{ex.ToString()}""}}";
                }
            }
            else
            {
                return @"[""Json not start with { or [.""]";
            }
        }

只是为了给@Habib的答案添加一些东西，你也可以检查给定的JSON是否来自有效的类型:

public static bool IsValidJson<T>(this string strInput)
{
    if(string.IsNullOrWhiteSpace(strInput)) return false;

    strInput = strInput.Trim();
    if ((strInput.StartsWith("{") && strInput.EndsWith("}")) || //For object
        (strInput.StartsWith("[") && strInput.EndsWith("]"))) //For array
    {
        try
        {
            var obj = JsonConvert.DeserializeObject<T>(strInput);
            return true;
        }
        catch // not valid
        {             
            return false;
        }
    }
    else
    {
        return false;
    }
}

我找到了JToken。Parse错误地解析无效的JSON，如下所示:

{
"Id" : , 
"Status" : 2
}

将JSON字符串粘贴到http://jsonlint.com/ -无效。

所以我用:

public static bool IsValidJson(this string input)
{
    input = input.Trim();
    if ((input.StartsWith("{") && input.EndsWith("}")) || //For object
        (input.StartsWith("[") && input.EndsWith("]"))) //For array
    {
        try
        {
            //parse the input into a JObject
            var jObject = JObject.Parse(input);

            foreach(var jo in jObject)
            {
                string name = jo.Key;
                JToken value = jo.Value;

                //if the element has a missing value, it will be Undefined - this is invalid
                if (value.Type == JTokenType.Undefined)
                {
                    return false;
                }
            }
        }
        catch (JsonReaderException jex)
        {
            //Exception in parsing json
            Console.WriteLine(jex.Message);
            return false;
        }
        catch (Exception ex) //some other exception
        {
            Console.WriteLine(ex.ToString());
            return false;
        }
    }
    else
    {
        return false;
    }

    return true;
}

关于汤姆·比奇的回答;相反，我想到了以下几点:

public bool ValidateJSON(string s)
{
    try
    {
        JToken.Parse(s);
        return true;
    }
    catch (JsonReaderException ex)
    {
        Trace.WriteLine(ex);
        return false;
    }
}

有以下用法:

if (ValidateJSON(strMsg))
{
    var newGroup = DeserializeGroup(strMsg);
}

下面是一个基于Habib答案的TryParse扩展方法:

public static bool TryParse(this string strInput, out JToken output)
{
    if (String.IsNullOrWhiteSpace(strInput))
    {
        output = null;
        return false;
    }
    strInput = strInput.Trim();
    if ((strInput.StartsWith("{") && strInput.EndsWith("}")) || //For object
        (strInput.StartsWith("[") && strInput.EndsWith("]"))) //For array
    {
        try
        {
            output = JToken.Parse(strInput);
            return true;
        }
        catch (JsonReaderException jex)
        {
            //Exception in parsing json
            //optional: LogError(jex);
            output = null;
            return false;
        }
        catch (Exception ex) //some other exception
        {
            //optional: LogError(ex);
            output = null;
            return false;
        }
    }
    else
    {
        output = null;
        return false;
    }
}

用法:

JToken jToken;
if (strJson.TryParse(out jToken))
{
    // work with jToken
}
else
{
    // not valid json
}

即使返回异常也返回json字符串的扩展:

        public static string OnlyValidJson(this string strInput)
        {
            if (string.IsNullOrWhiteSpace(strInput)) { return @"[""Json is empty""]"; }
            strInput = strInput.Trim();
            if ((strInput.StartsWith("{") && strInput.EndsWith("}")) ||
                (strInput.StartsWith("[") && strInput.EndsWith("]")))
            {
                try
                {
                    string strEscape = strInput.Replace("\\n", "").Replace("\\r", "").Replace("\n", "").Replace("\r", "");
                    JToken.Parse(strEscape);
                    return strEscape;
                }
                catch (JsonReaderException jex)
                {
                    return @$"{{""JsonReaderException"":""{jex.Message}""}}";
                }
                catch (Exception ex)
                {
                    Console.WriteLine(ex.ToString());
                    return @$"{{""Exception"":""{ex.ToString()}""}}";
                }
            }
            else
            {
                return @"[""Json not start with { or [.""]";
            }
        }