解析HTTP响应JSON转对象时遇Newtonsoft.Json.JsonReaderException错误求助

错误详情 #

Error : Newtonsoft.Json.JsonReaderException: Unexpected character encountered while parsing number: G. Path '', line 1, position 7.
at Newtonsoft.Json.JsonTextReader.ReadNumberCharIntoBuffer(Char currentChar, Int32 charPos)
at Newtonsoft.Json.JsonTextReader.ReadNumberIntoBuffer()
at Newtonsoft.Json.JsonTextReader.ParseNumber(ReadType readType)
at Newtonsoft.Json.JsonTextReader.ParseValue()
at Newtonsoft.Json.JsonReader.ReadAndMoveToContent()
at Newtonsoft.Json.JsonReader.ReadForType(JsonContract contract, Boolean hasConverter)
at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.Deserialize(JsonReader reader, Type objectType, Boolean checkAdditionalContent)
at Newtonsoft.Json.JsonSerializer.DeserializeInternal(JsonReader reader, Type objectType)
at Newtonsoft.Json.JsonSerializer.Deserialize(JsonReader reader, Type objectType)
at Newtonsoft.Json.JsonConvert.DeserializeObject(String value, Type type, JsonSerializerSettings settings)
at Pando.DataLayer.Repositories.DBSRepository.DBSAPIint() in D:\agent_work\242\s\Application\DBS.DataLayer\Repositories\DBSRepository.cs:line 137

问题代码 #

HttpContent httpContent = new StringContent(encryptedMessage);
httpContent.Headers.ContentType = new MediaTypeHeaderValue("text/plain");
var response = await httpClient.PostAsync(apiUrl, httpContent);
string responseMsg1 = await response.Content.ReadAsStringAsync();
HttpStatusCode statusCode = response.StatusCode;
string status = response.StatusCode.ToString();
int codes = ((int)response.StatusCode);
//var dataObject = (JObject)JsonConvert.DeserializeObject(await response.Content.ReadAsStringAsync());  //Json is capture in dataobject
var dataObject = JsonConvert.DeserializeObject(responseMsg1);  //Json is capture in dataobject
var responseCode = codes.ToString();
var Jsondata = dataObject.ToString();
 
var error1 = new SqlParameter("@errorDesc", Jsondata);
int Qryres1 = dbc.Database.ExecuteSqlRaw("exec[dbo].[DBSlog] @errorDesc", error1);
//EOC 19-06-23
//var json = new SqlParameter("@json", jsonData);
//var response = new SqlParameter("@responseCode", responseCode);
var Json = new SqlParameter("@Jsondata", Jsondata);
var msgid = new SqlParameter("@msgid", od.msgId);

//var Status = new SqlParameter("@status", status);
//var Ack_type = new SqlParameter("@type", type);
//updating the status of data 
dbc.Database.ExecuteSqlRaw("exec[dbo].[Usp_JsonToTable] @Jsondata @msgid", Json,msgid);
response.EnsureSuccessStatusCode();

问题分析 #

错误提示明确指出：解析数字时在第1行第7位遇到了意外字符G。这说明你尝试反序列化的responseMsg1不是合法的JSON字符串，可能的原因包括：

• API返回的是错误响应（如500错误页、纯文本错误信息）而非JSON
• 响应内容是加密后的原始数据，未经过解密处理
• 响应存在编码问题，导致字符串格式异常
• API返回的内容本身不符合JSON规范

解决方案 #

1. 排查原始响应内容 #

在反序列化前添加日志或打印，确认responseMsg1的实际内容，这是定位问题的核心：

string responseMsg1 = await response.Content.ReadAsStringAsync();
// 临时输出原始响应，可替换为日志记录
Console.WriteLine($"Raw API Response: {responseMsg1}");

通过这一步能直接看到返回的内容是否为合法JSON，比如如果返回的是类似"500GatewayError"这类带G的字符串，就能明确问题所在。

2. 提前校验HTTP响应状态 #

原代码中response.EnsureSuccessStatusCode()放在最后，导致即使API返回错误状态（如400、500），仍会尝试解析非JSON内容。应提前校验：

var response = await httpClient.PostAsync(apiUrl, httpContent);
// 先确保请求成功，避免处理错误响应
response.EnsureSuccessStatusCode();
string responseMsg1 = await response.Content.ReadAsStringAsync();

3. 添加反序列化异常捕获 #

在反序列化逻辑外包裹try-catch，记录详细错误信息，便于排查：

var dataObject = default(JObject);
try
{
    dataObject = JsonConvert.DeserializeObject<JObject>(responseMsg1);
}
catch (JsonReaderException ex)
{
    // 记录错误和原始响应，方便定位
    Console.WriteLine($"Deserialization Failed: {ex.Message}, Raw Response: {responseMsg1}");
    throw; // 或根据业务逻辑做降级处理
}

4. 确认响应解密逻辑（如果需要） #

如果API要求请求加密，返回的响应可能也是加密状态，需要先解密responseMsg1，再进行JSON反序列化。

修正后的完整代码示例 #

HttpContent httpContent = new StringContent(encryptedMessage);
httpContent.Headers.ContentType = new MediaTypeHeaderValue("text/plain");
var response = await httpClient.PostAsync(apiUrl, httpContent);

// 提前校验响应状态
response.EnsureSuccessStatusCode();

string responseMsg1 = await response.Content.ReadAsStringAsync();
// 临时输出原始响应，排查问题用
Console.WriteLine($"Raw API Response: {responseMsg1}");

HttpStatusCode statusCode = response.StatusCode;
string status = response.StatusCode.ToString();
int codes = ((int)response.StatusCode);

var dataObject = default(JObject);
try
{
    dataObject = JsonConvert.DeserializeObject<JObject>(responseMsg1);
}
catch (JsonReaderException ex)
{
    Console.WriteLine($"Deserialization Error: {ex.Message}, Raw Response: {responseMsg1}");
    throw;
}

var responseCode = codes.ToString();
var Jsondata = dataObject.ToString();

var error1 = new SqlParameter("@errorDesc", Jsondata);
int Qryres1 = dbc.Database.ExecuteSqlRaw("exec[dbo].[DBSlog] @errorDesc", error1);

var Json = new SqlParameter("@Jsondata", Jsondata);
var msgid = new SqlParameter("@msgid", od.msgId);

// 注意存储过程参数间添加逗号分隔
dbc.Database.ExecuteSqlRaw("exec[dbo].[Usp_JsonToTable] @Jsondata, @msgid", Json, msgid);

内容的提问来源于stack exchange，提问作者Yash