Asp.Net MVC大型项目实践整合 NHibernate与Json序列化

通过NHibernate我们多表查询是实现了 但由于查询出来的集合中的对象“不是平的”，如何在送到UI绑定成了问题。ExtJs UI组件的数据绑定支持多种格式，如简单数组，Json,Xml。在本项目中我们统一，服务器端通过Json把数据传输到Ext进行解析和绑定。

那么我们现在只需要找个方便的办法把我们的.Net对象（集合）转化为Json格式的字符串就可以了。于是乎我们google了一下发现.Net下还真有这么个方法能把.Net对象序列化成Json字符串
new System.Web.Script.Serialization.JavaScriptSerializer().Serialize([要序列化的.Net对象]);
Asp.Net Mvc里也有（看过MVC源码后可知，其实里面用的也是上面的JavaScriptSerializer）：

public ActionResult test5()
{
return Json([要序列化的Json对象]);
}

我们试试

//Json输出试一试
public ActionResult test5()
{
return Json(new {
Name = "弦哥",
Age = 26,
IsMarry = true,
MyDog = new { Name = "大海", Age = 1, Variety="罗威纳" }
});}

输出的Json字符串为：{"Name":"弦哥","Age":26,"IsMarry":true,"MyDog":{"Name":"大海","Age":1,"Variety":"罗威纳"}}

但把NHibernate查询出的集合对象也放进去序列化一下：出现错误了，序列化类型对象的时候检测到对象循环使用。

解决方法：

我们用Json.Net(Newtonsoft.Json),下面我们继承他的DefaultContractResolver类并重写GetSerializableMembers方法 ，定义我们自己的Json序列化规则NHibernateContractResolver,代码如下：

namespace Demo.HIS.FrameWork
{
/// <summary>
/// 自定义Json.Net的规则
/// </summary>
public class NHibernateContractResolver : DefaultContractResolver
{
private string[] exceptMemberName;//例外

private static readonly MemberInfo[] NHibernateProxyInterfaceMembers = typeof(INHibernateProxy).GetMembers();

public NHibernateContractResolver(string[] exceptMemberName)
{
this.exceptMemberName = exceptMemberName;
}
protected override List<MemberInfo> GetSerializableMembers(Type objectType)
{
var members = new List<PropertyInfo>(objectType.GetProperties());
members.RemoveAll(memberInfo =>
// (IsMemberNames(memberInfo))||
(IsMemberPartOfNHibernateProxyInterface(memberInfo))||
(IsMemberDynamicProxyMixin(memberInfo))||
(IsMemberMarkedWithIgnoreAttribute(memberInfo,objectType))||
(IsInheritedISet(memberInfo))||
(IsInheritedEntity(memberInfo))
);

var actualMemberInfos = new List<MemberInfo>();
foreach (var memberInfo in members)
{
var infos = memberInfo.DeclaringType.BaseType.GetMember(memberInfo.Name);
actualMemberInfos.Add(infos.Length == 0 ? memberInfo : infos[0]);
//Debug.WriteLine(memberInfo.Name);
}
return actualMemberInfos;
}
private static bool IsMemberDynamicProxyMixin(PropertyInfo memberInfo)
{
return memberInfo.Name == "__interceptors";
}

private static bool IsMemberPartOfNHibernateProxyInterface(PropertyInfo memberInfo)
{
return Array.Exists(NHibernateProxyInterfaceMembers, mi => memberInfo.Name == mi.Name);
}

private static bool IsMemberMarkedWithIgnoreAttribute(PropertyInfo memberInfo, Type objectType)
{
var infos = typeof(INHibernateProxy).IsAssignableFrom(objectType) ?
objectType.BaseType.GetMember(memberInfo.Name) :
objectType.GetMember(memberInfo.Name);
return infos[0].GetCustomAttributes(typeof(JsonIgnoreAttribute), true).Length > 0;
}

private bool IsExceptMember(PropertyInfo memberInfo)
{
if (exceptMemberName == null)
return false;
return Array.Exists(exceptMemberName, i => memberInfo.Name == i);
}

private bool IsInheritedISet(PropertyInfo memberInfo)
{
return (memberInfo.PropertyType.Name == "ISet`1" && !IsExceptMember(memberInfo));
}

private bool IsInheritedEntity(PropertyInfo memberInfo)
{
return (FindBaseType(memberInfo.PropertyType).Name == "Entity" && !IsExceptMember(memberInfo));
}
private static Type FindBaseType(Type type)
{
if (!type.IsClass)
return type;
if (type.Name == "Entity"||type.Name=="Object")
{
return type;
}
return FindBaseType(type.BaseType);
}
}
}

代码有点复杂，涉及到对NHibernate动态代理的一些特殊处理。大概意思就是如果对象里的属性的类型为Entity或ISet<T>的我们就忽略掉，不序列化，除非我们显示指定需要序列化的属性名。

为了方便Asp.Net MVC调用我们自己的Json序列化，我们自定义一个ActionResult:

public class FormatJsonResult : ActionResult
{
public string[] ExceptMemberName { get; set; }
public Object Data { get; set; }
public override void ExecuteResult(ControllerContext context)
{
if (context == null)
{
throw new ArgumentNullException("context");
}
HttpResponseBase response = context.HttpContext.Response;
response.ContentType = "application/json";

StringWriter sw = new StringWriter();
JsonSerializer serializer = JsonSerializer.Create(
new JsonSerializerSettings
{
Converters = new JsonConverter[] { new Newtonsoft.Json.Converters.JavaScriptDateTimeConverter() },
ReferenceLoopHandling = ReferenceLoopHandling.Ignore,
NullValueHandling = NullValueHandling.Ignore,
ContractResolver = new NHibernateContractResolver(ExceptMemberName)
}
);

using (JsonWriter jsonWriter = new JsonTextWriter(sw))
{
jsonWriter.Formatting = Formatting.Indented;
serializer.Serialize(jsonWriter, Data);
}
response.Write(sw.ToString());
}
}

再给Asp.net MVC的Controller类定义两个扩展方法：

public static class FormatJsonExtension
{
public static FormatJsonResult JsonFormat(this Controller c, object data, string[] exceptMemberName)
{
FormatJsonResult result = new FormatJsonResult();
result.Data = data;
result.ExceptMemberName = exceptMemberName;
return result;
}

public static FormatJsonResult JsonFormat(this Controller c, object data)
{
return JsonFormat(c, data, null);
}

}

//测试一下
public ActionResult test()
{
Demo.HIS.Infrastructure.Core.Repositories.IDictionaryRepository r = new Demo.HIS.Infrastructure.Repositories.Data.DictionaryRepositoryImpl();
long total;
var list = r.GetPlistByCategoryId("48391bb4-471b-4499-899b-cea9748e1a7b", 0, 15, "Index", "desc", null, out total);

//我们自己的Json序列化方法
return this.JsonFormat(
list,
new string[] { "Category" });//指定需要序列化属性“Category”
}