HttpContextBase context = (HttpContextBase)Request.Properties\["MS\_HttpContext"\];//获取传统context  
        HttpRequestBase request = context.Request;//定义传统request对象  
        var t = request.Form\["sets"\];

//返回字符串
//请求方式为 http://localhost:4243/Home/Index0?$format=json
[HttpGet]

    public string Index0()  
    {  
        return "value1";  
    }  
    //返回json对象  
    \[HttpGet\]

    public IEnumerable<string> Index00()  
    {  
        return new string\[\] { "value1", "value2" };  
    }  
    \[HttpGet\]  
    public string\[\] Index1()  
    {  
        return new string\[\] { "value1", "value2" };  
    }  
    \[HttpGet\]  
    public HttpResponseMessage Index2()  
    {  
        string json = string.Format("\[{{ \\"re1\\":{0},\\"re2\\":{0},\\"re3\\":{0} }},{{ \\"re1\\":{0},\\"re2\\":{0},\\"re3\\":{0} }}\]",string.Empty);// "{\\"result\\":\\"jsons\\"}";  
        return new HttpResponseMessage { Content = new StringContent(json, System.Text.Encoding.UTF8, "application/json") };  
    }

        // Web API 配置和服务  
        config.Formatters.JsonFormatter.AddQueryStringMapping("$format", "json", "application/json");  
        config.Formatters.XmlFormatter.AddQueryStringMapping("$format", "xml", "application/xml");  
        // Web API 路由  
        config.MapHttpAttributeRoutes();