JavaScript Object Notation é um padrão para troca de
informações. É fácil para homens ler e escrever e maquinas podem facilmente
entender e gerar. Esse padrão é baseado no JavaScript Programming Language, Standard
ECMA-262 3rd Edition - December 1999. JSON é um formato de texto que é
independente de linguagem, mas usa convenções familiares a família C.
JSON é construído em 2 estruturas:
1 – Uma coleção de pares de chave(string)/valor(string,
number, object, array, true, false, null)
2 – Uma lista ordenada de valores
Uma grande vantagem do JSON é que ele tem pouca verbosidade,
ainda mais quando se comparado com WebService por exemplo. Vários aplicativos
online, que precisam disponibilizar informações de forma simples, fazem
comunicações por JSON, como exemplo há o foursquare.
Veja um exemplo de um JSON válido
Um exemplo simples de leitura JSON no C#
Crie um projeto Console e adicione referência a System.Runtime.Serialization
Adicione o código abaixo no arquivo Program.cs, fazendo alterações necessárias ao namespace:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Runtime.Serialization.Json;
using System.Runtime.Serialization;
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
GoogleSearchResults g1 = new GoogleSearchResults();
const string json = @"{""responseData"": {""results"":[{""GsearchResultClass"":""GwebSearch"",""unescapedUrl"":""http://www.cheese.com/"",""url"":""http://www.cheese.com/"",""visibleUrl"":""www.cheese.com"",""cacheUrl"":""http://www.google.com/search?q\u003dcache:bkg1gwNt8u4J:www.cheese.com"",""title"":""\u003cb\u003eCHEESE\u003c/b\u003e.COM - All about \u003cb\u003echeese\u003c/b\u003e!."",""titleNoFormatting"":""CHEESE.COM - All about cheese!."",""content"":""\u003cb\u003eCheese\u003c/b\u003e - everything you want to know about it. Search \u003cb\u003echeese\u003c/b\u003e by name, by types of milk, by textures and by countries.""},{""GsearchResultClass"":""GwebSearch"",""unescapedUrl"":""http://en.wikipedia.org/wiki/Cheese"",""url"":""http://en.wikipedia.org/wiki/Cheese"",""visibleUrl"":""en.wikipedia.org"",""cacheUrl"":""http://www.google.com/search?q\u003dcache:n9icdgMlCXIJ:en.wikipedia.org"",""title"":""\u003cb\u003eCheese\u003c/b\u003e - Wikipedia, the free encyclopedia"",""titleNoFormatting"":""Cheese - Wikipedia, the free encyclopedia"",""content"":""\u003cb\u003eCheese\u003c/b\u003e is a food consisting of proteins and fat from milk, usually the milk of cows, buffalo, goats, or sheep. It is produced by coagulation of the milk \u003cb\u003e...\u003c/b\u003e""},{""GsearchResultClass"":""GwebSearch"",""unescapedUrl"":""http://www.ilovecheese.com/"",""url"":""http://www.ilovecheese.com/"",""visibleUrl"":""www.ilovecheese.com"",""cacheUrl"":""http://www.google.com/search?q\u003dcache:GBhRR8ytMhQJ:www.ilovecheese.com"",""title"":""I Love \u003cb\u003eCheese\u003c/b\u003e!, Homepage"",""titleNoFormatting"":""I Love Cheese!, Homepage"",""content"":""The American Dairy Association\u0026#39;s official site includes recipes and information on nutrition and storage of \u003cb\u003echeese\u003c/b\u003e.""},{""GsearchResultClass"":""GwebSearch"",""unescapedUrl"":""http://www.gnome.org/projects/cheese/"",""url"":""http://www.gnome.org/projects/cheese/"",""visibleUrl"":""www.gnome.org"",""cacheUrl"":""http://www.google.com/search?q\u003dcache:jvfWnVcSFeQJ:www.gnome.org"",""title"":""\u003cb\u003eCheese\u003c/b\u003e"",""titleNoFormatting"":""Cheese"",""content"":""\u003cb\u003eCheese\u003c/b\u003e uses your webcam to take photos and videos, applies fancy special effects and lets you share the fun with others. It was written as part of Google\u0026#39;s \u003cb\u003e...\u003c/b\u003e""}],""cursor"":{""pages"":[{""start"":""0"",""label"":1},{""start"":""4"",""label"":2},{""start"":""8"",""label"":3},{""start"":""12"",""label"":4},{""start"":""16"",""label"":5},{""start"":""20"",""label"":6},{""start"":""24"",""label"":7},{""start"":""28"",""label"":8}],""estimatedResultCount"":""14400000"",""currentPageIndex"":0,""moreResultsUrl"":""http://www.google.com/search?oe\u003dutf8\u0026ie\u003dutf8\u0026source\u003duds\u0026start\u003d0\u0026hl\u003den-GB\u0026q\u003dcheese""}}, ""responseDetails"": null, ""responseStatus"": 200}";
g1 = JSONHelper.Deserialise(json);
foreach (Results x in g1.responseData.results)
{
// Anything you want to get
Console.WriteLine(x.content);
}
}
}
public class JSONHelper
{
public static T Deserialise(string json)
{
using (var ms = new MemoryStream(Encoding.Unicode.GetBytes(json)))
{
var serialiser = new DataContractJsonSerializer(typeof(T));
return (T)serialiser.ReadObject(ms);
}
}
}
[DataContract]
public class GoogleSearchResults
{
[DataMember]
public ResponseData responseData { get; set; }
}
[DataContract]
public class ResponseData
{
[DataMember]
public IEnumerable results { get; set; }
}
[DataContract]
public class Results
{
[DataMember]
public string unescapedUrl { get; set; }
[DataMember]
public string url { get; set; }
[DataMember]
public string visibleUrl { get; set; }
[DataMember]
public string cacheUrl { get; set; }
[DataMember]
public string title { get; set; }
[DataMember]
public string titleNoFormatting { get; set; }
[DataMember]
public string content { get; set; }
}
}
