WebService返回JSON被方法名包裹，如何获取原始JSON数据？

我开发了一个供Android应用调用的WebService，Login方法本该直接返回构造好的JSON字符串，但实际返回结果被自动套在了LoginResult字段里。

手动构造的JSON：

{ "UserID": "xxx", "Salutation": "xxx", "Title": "xxx", "Name": "xxx", "Lastname": "xxx" }

实际返回的结果：

{ "LoginResult": { "UserID": "xxx", "Salutation": "xxx", "Title": "xxx", "Name": "xxx", "Lastname": "xxx" }}

当前Login方法代码：

public string Login(string username, string passwort)
{
    string json = "error";
    try
    {
        var login = Namespace.ViewModels.LoginData.SelectByUserNamePassword(username, passwort);
        Namespace.Models.WebAppUser webUser = new Namespace.Models.WebAppUser();
        lock (webUser)
        {
            webUser = new Namespace.Controllers.ApplicationController().setWebUserT(Convert.ToInt32(login.UserID), Convert.ToInt32(login.BetriebID), login.BetriebTyp, login.SessionID, login.UniqueID, login.DBName);
        }

        if (webUser != null && webUser.UserID != -1)
        {
            json = "{ \"UserID\": \"" + login.UserID + "\", \"Salutation\": \"" + webUser.Salutation + "\", \"Title\": \"" + webUser.Title + "\", \"Name\": \"" + webUser.Name + "\", \"Lastname\": \"" + webUser.Lastname + "\" }";
        }
    }
    catch (Exception ex)
    {
        SimpleLogger.Exception(ex);
    }
    return json;
}

1. 改用返回HttpResponseMessage替代字符串 #

WebService框架（如ASMX或WCF）默认会包装返回的字符串，直接返回HttpResponseMessage可绕过该逻辑：

public HttpResponseMessage Login(string username, string passwort)
{
    string json = "\"error\"";
    try
    {
        var login = Namespace.ViewModels.LoginData.SelectByUserNamePassword(username, passwort);
        Namespace.Models.WebAppUser webUser = new Namespace.Models.WebAppUser();
        lock (webUser)
        {
            webUser = new Namespace.Controllers.ApplicationController().setWebUserT(Convert.ToInt32(login.UserID), Convert.ToInt32(login.BetriebID), login.BetriebTyp, login.SessionID, login.UniqueID, login.DBName);
        }

        if (webUser != null && webUser.UserID != -1)
        {
            json = "{ \"UserID\": \"" + login.UserID + "\", \"Salutation\": \"" + webUser.Salutation + "\", \"Title\": \"" + webUser.Title + "\", \"Name\": \"" + webUser.Name + "\", \"Lastname\": \"" + webUser.Lastname + "\" }";
        }
    }
    catch (Exception ex)
    {
        SimpleLogger.Exception(ex);
    }
    return new HttpResponseMessage(HttpStatusCode.OK)
    {
        Content = new StringContent(json, Encoding.UTF8, "application/json")
    };
}

2. 避免手动拼接JSON（推荐优化） #

手动拼接JSON易出错，建议用序列化库（如Newtonsoft.Json）直接序列化对象：

// 先定义响应数据类
public class LoginResponse
{
    public string UserID { get; set; }
    public string Salutation { get; set; }
    public string Title { get; set; }
    public string Name { get; set; }
    public string Lastname { get; set; }
}

// 修改Login方法中的JSON构造逻辑
if (webUser != null && webUser.UserID != -1)
{
    var response = new LoginResponse
    {
        UserID = login.UserID,
        Salutation = webUser.Salutation,
        Title = webUser.Title,
        Name = webUser.Name,
        Lastname = webUser.Lastname
    };
    json = JsonConvert.SerializeObject(response);
}

3. ASMX服务专属配置：直接写入响应流 #

如果是ASMX服务，可在WebMethod上添加特性，改为直接写入响应流：

[WebMethod]
[ScriptMethod(ResponseFormat = ResponseFormat.Json)]
public void Login(string username, string passwort)
{
    string json = "\"error\"";
    try
    {
        // 原有业务逻辑...
    }
    catch (Exception ex)
    {
        SimpleLogger.Exception(ex);
    }
    Context.Response.ContentType = "application/json";
    Context.Response.Write(json);
}

内容的提问来源于stack exchange，提问作者Mike