我正在通过gson解析一个Json字符串,这是Json字符串

[
{
    "ID": 1,"Name": "Australia","Active": true
},{
    "ID": 3,"Name": "Kiev",{
    "ID": 4,"Name": "South Africa",{
    "ID": 5,"Name": "Stockholm",{
    "ID": 6,"Name": "Paris",{
    "ID": 7,"Name": "Moscow",{
    "ID": 8,"Name": "New York City",{
    "ID": 9,"Name": "Germany",{
    "ID": 10,"Name": "copenhagen",{
    "ID": 11,"Name": "Amsterdam","Active": true
}
]

这是将被使用的对象

public class MyBranch extends Entity {

public MyBranch () {
    super();
}

public MyBranch (int id,String name,String isActive) {
    super();
    _ID = id;
    _Name = name;
    _Active = isActive;
}

@Column(name = "id",primaryKey = true)
public int _ID;
public String _Name;
public String _Active;

}
Gson gson = new Gson();
Type t = new Typetoken<List<MyBranch >>() {}.getType();     
List<MyBranch > list = (List<MyBranch >) gson.fromJson(json,t);

构造的列表,它有10个对象,但问题是对象的所有数据成员都是null,我不会对此有什么不妥.实体是OrmDroid的实体类.

MyBranch类中字段的名称与json中的字段不匹配,因此您必须使用Serializedname批注.

import com.google.gson.annotations.Serializedname;

public class MyBranch extends Entity {
    public MyBranch () {
        super();
    }

    public MyBranch (int id,String isActive) {
        super();
        _ID = id;
        _Name = name;
        _Active = isActive;
    }

    @Column(name = "id",primaryKey = true)
    @Serializedname("ID")
    public int _ID;

    @Serializedname("Name")
    public String _Name;

    @Serializedname("Active")
    public String _Active;
}

编辑：
您还可以通过简单重命名MyBranch字段来避免使用Serializedname注释：

import com.google.gson.annotations.Serializedname;

public class MyBranch extends Entity {
    public MyBranch () {
        super();
    }

    public MyBranch (int id,String isActive) {
        super();
        ID = id;
        Name = name;
        Active = isActive;
    }

    @Column(name = "id",primaryKey = true)
    public int ID;
    public String Name;
    public String Active;
}

我有一个动作,它返回一个特定类的对象的JsonResult.我已经使用一些attrib来装饰这个类的属性以避免使用null字段.类定义是：

private class GanttEvent
    {
        public String name { get; set; }

        [JsonProperty(NullValueHandling = NullValueHandling.Ignore)]
        public String desc { get; set; }

        [JsonProperty(NullValueHandling = NullValueHandling.Ignore)]
        public List<GanttValue> values { get; set; }
    }

在我的动作中我使用了一个对象

var res = new List<GanttEvent>();

我回来使用：

return Json(res,JsonRequestBehavior.AllowGet);

不幸的是,我仍然在输出时收到空值：

[{"name":"1.1 PREVIOS AL INICIO ","desc":null,"values":null},{"name":"F04-PGA-S10","desc":"Acta preconstrucción",{"name":"F37-PGA-S10","desc":"Plan de inversión del anticipo",{"name":"F09-PGA-S10","desc":"Acta de vecindad",{"name":"F05-PGA-S10","desc":"Acta de inicio",{"name":"F01-PGA-S10","desc":"Desembolso de anticipo","values":null}]

我错过了什么或做错了什么？

正如Brad Christie所说,MVC4仍然使用JavaScriptSerializer,因此为了让你的对象被Json.Net序列化,你将不得不执行几个步骤.

首先,从JsonResult继承一个新类JsonNetResult,如下所示(基于this solution)：

public class JsonNetResult : JsonResult
{
    public JsonNetResult()
    {
        this.ContentType = "application/json";
    }

    public JsonNetResult(object data,string contentType,Encoding contentEncoding,JsonRequestBehavior jsonRequestBehavior)
    {
        this.ContentEncoding = contentEncoding;
        this.ContentType = !string.IsNullOrWhiteSpace(contentType) ? contentType : "application/json";
        this.Data = data;
        this.JsonRequestBehavior = jsonRequestBehavior;
    }

    public override void ExecuteResult(ControllerContext context)
    {
        if (context == null)
            throw new ArgumentNullException("context");

        var response = context.HttpContext.Response;

        response.ContentType = !String.IsNullOrEmpty(ContentType) ? ContentType : "application/json";

        if (ContentEncoding != null)
            response.ContentEncoding = ContentEncoding;

        if (Data == null)
            return;

        // If you need special handling,you can call another form of SerializeObject below
        var serializedobject = JsonConvert.SerializeObject(Data,Formatting.None);
        response.Write(serializedobject);
    }
}

然后,在您的控制器中,重写Json方法以使用新类：

protected override JsonResult Json(object data,JsonRequestBehavior behavior)
{
    return new JsonNetResult(data,contentType,contentEncoding,behavior);
}

我试图反序列化这个字符串：

string _jsonObject = {\"Ad\":{\"Type\":\"Request"\,\"IdAd\":\"xxx@xxx.com\",\"Category\":\"cat\",\"SubCategory\":\"subcat\"},\"Position\":{\"Latitude\":\"38.255\",\"Longitude\":\"1.2\",\"Imei\":\"0123456789\"};
}";

Message _message = JsonConvert.DeserializeObject<Message>(_jsonObject);

适用于“广告”而非实际的“位置”.
任何的想法 ？

为了帮助可能遇到此问题的其他人或与之相关的人…

在我的例子中,我有一个带有其他对象数组的对象,并且在反序列化后,这些子对象上的一个引用类型属性始终为null.我尝试了各种各样的东西,包括下载JSON.Net源代码并逐步完成它以找到失败点.

长话短说,问题当然是我自己的问题.这是我的JSON和类的高度简化版本.

JSON

{
    "$id": "1","RowCount": 10,"Rows": [{
        "$id": 2","ItemId": "1","ItemName": "Some Item","Owner": {
            "Name": "John Doe","Id": "711D04F5-586F-4FD4-8369-4C00B51DD86F",// other properties...
        },"OwnerId": "711D04F5-586F-4FD4-8369-4C00B51DD86F"
    },// more rows
    ]
}

类

public class Items
{
    public int RowCount { get; set; }
    public IEnumerable<Item> Rows { get; set; }
}

public class Item
{
    private string ownerId;

    public string ItemId { get; set; }
    public string ItemName { get; set; }
    public Person Owner { get; set; }
    public string OwnerId
    {
        get { return this.ownerId; }
        set {
            if (value != this.ownerId)
            {
                this.Owner = null;
            }
            this.ownerId = value;
        }
    }
}

public class Person
{
    public string Name { get; set; }
    public string Id { get; set; }
    // other properties
}

发生的事情是,因为Owner属性出现在OwnerId属性之前的JSON中,所以当设置了OwnerId属性时,setter代码确定当前值与设置的值不同(因为当前值是null),因此它将Owner属性设置为null.

为了解决这个问题,我还检查了针对Owner对象的id设置的值,如果它们相同,则跳过将Owner设置为null.

不可否认,我的问题的原因可能并不是每个人都一样,但这至少是一个警示故事,要仔细检查在反序列化过程中初始化对象时发生的情况.