解析JSON
我们知道上述接口返回的数据是json格式的，为此我们需要通过C#对json类型的数据进行解析。为此我们在项目中添加System.ServiceModel.Web.dll的引用，以便使用DataContractJsonSerializer类。
调用http://api.whatthetrend.com/api/v2/trends.json?api_key=1eb228f23d41dd3e8a042af5cf072ccfe41d0c22接口返回的json格式数据如下：
{
"api_version" : "2.0",
"as_of" : "2009-10-15 19:57:01",
"trends" : [
{ "description" : { "created_at" : "2009-10-15 19:54:32",
"text" : "A 6 year old was believed to be stuck in a homemade hot air balloon in Denver, Colorado. The balloon landed with no boy found inside. The boy is still missing.",
"score" : "0"
},
"first_trended_at" : "2009-10-15 19:00:01",
"last_trended_at" : "2009-10-15 19:55:01",
"name" : "Colorado",
"newly_trending" : "0",
"query" : "Colorado",
"trend_index" : "1",
"url" : "http://search.twitter.com/search?q=Colorado",
"category_id" : "11",
"category_name" : "News",
"locked" : false
},
{ "description" : { "created_at" : "2009-10-15 19:54:10",
"text" : "A 6 year old was believed to be stuck in a homemade hot air balloon in Denver, Colorado. The balloon landed with no boy found inside. The boy is still missing.",
"score" : "0"
},
"first_trended_at" : "2009-10-15 19:30:01",
"last_trended_at" : "2009-10-15 19:55:01",
"name" : "#saveballoonboy",
"newly_trending" : "0",
"query" : "#saveballoonboy",
"trend_index" : "2",
"url" : "http://search.twitter.com/search?q=%23saveballoonboy",
"category_id" : "11",
"category_name" : "News",
"locked" : false
}, ...
]
}
"api_version" : "2.0",
"as_of" : "2009-10-15 19:57:01",
"trends" : [
{ "description" : { "created_at" : "2009-10-15 19:54:32",
"text" : "A 6 year old was believed to be stuck in a homemade hot air balloon in Denver, Colorado. The balloon landed with no boy found inside. The boy is still missing.",
"score" : "0"
},
"first_trended_at" : "2009-10-15 19:00:01",
"last_trended_at" : "2009-10-15 19:55:01",
"name" : "Colorado",
"newly_trending" : "0",
"query" : "Colorado",
"trend_index" : "1",
"url" : "http://search.twitter.com/search?q=Colorado",
"category_id" : "11",
"category_name" : "News",
"locked" : false
},
{ "description" : { "created_at" : "2009-10-15 19:54:10",
"text" : "A 6 year old was believed to be stuck in a homemade hot air balloon in Denver, Colorado. The balloon landed with no boy found inside. The boy is still missing.",
"score" : "0"
},
"first_trended_at" : "2009-10-15 19:30:01",
"last_trended_at" : "2009-10-15 19:55:01",
"name" : "#saveballoonboy",
"newly_trending" : "0",
"query" : "#saveballoonboy",
"trend_index" : "2",
"url" : "http://search.twitter.com/search?q=%23saveballoonboy",
"category_id" : "11",
"category_name" : "News",
"locked" : false
}, ...
]
}
是的，这样的数据看起来是不是非常吓人，这里已经将一些关键的数据字段用红色字体标记出来。我们可以将这个json数据分为三部分
api_version
trends
as_of
而trends 是由如下属性构成的：
name
trend_id
url
category_id
category_name
query
description
first_trended_at
last_trended_at
newly_trending
trend_index
locked
description是由如下属性构成的：
created_at
text
score
接下来我们需要使用C#构建这些数据的模式类，以便在程序中装配和使用数据。下面是这些类的代码。
/// <summary>
/// Model for twitter trend description
/// </summary>
public class TrendDescription
{
/// <summary>
/// Gets or sets the created_at.
/// </summary>
/// <value>The created_at.</value>
public DateTime created_at { get; set; }
/// <summary>
/// Gets or sets the text.
/// </summary>
/// <value>The text.</value>
public string text { get; set; }
/// <summary>
/// Gets or sets the score.
/// </summary>
/// <value>The score.</value>
public int score { get; set; }
}
/// <summary>
/// Model for twitter trend
/// </summary>
public class Trend
{
/// <summary>
/// Gets or sets the description.
/// </summary>
/// <value>The description.</value>
public TrendDescription description { get; set; }
/// <summary>
/// Gets or sets the first_trended_at.
/// </summary>
/// <value>The first_trended_at.</value>
public DateTime first_trended_at { get; set; }
/// <summary>
/// Gets or sets the last_trended_at.
/// </summary>
/// <value>The last_trended_at.</value>
public DateTime last_trended_at { get; set; }
/// <summary>
/// Gets or sets the name.
/// </summary>
/// <value>The name.</value>
public string name { get; set; }
/// <summary>
/// Gets or sets the newly_trending.
/// </summary>
/// <value>The newly_trending.</value>
public int newly_trending { get; set; }
/// <summary>
/// Gets or sets the query.
/// </summary>
/// <value>The query.</value>
public string query { get; set; }
/// <summary>
/// Gets or sets the trend_index.
/// </summary>
/// <value>The trend_index.</value>
public int trend_index { get; set; }
/// <summary>
/// Gets or sets the URL.
/// </summary>
/// <value>The URL.</value>
public string url { get; set; }
/// <summary>
/// Gets or sets the category_id.
/// </summary>
/// <value>The category_id.</value>
public int category_id { get; set; }
/// <summary>
/// Gets or sets the category_name.
/// </summary>
/// <value>The category_name.</value>
public string category_name { get; set; }
/// <summary>
/// Gets or sets a value indicating whether this <see cref="Trend"/> is locked.
/// </summary>
/// <value><c>true</c> if locked; otherwise, <c>false</c>.</value>
public bool locked { get; set; }
}
/// <summary>
/// Model for trends results
/// </summary>
public class TrendsResults
{
/// <summary>
/// Gets or sets the api_version.
/// </summary>
/// <value>The api_version.</value>
public string api_version { get; set; }
/// <summary>
/// Gets or sets the as_of.
/// </summary>
/// <value>The as_of.</value>
public DateTime as_of { get; set; }
/// <summary>
/// Gets or sets the trends.
/// </summary>
/// <value>The trends.</value>
public Trend[] trends { get; set; }
}
/// Model for twitter trend description
/// </summary>
public class TrendDescription
{
/// <summary>
/// Gets or sets the created_at.
/// </summary>
/// <value>The created_at.</value>
public DateTime created_at { get; set; }
/// <summary>
/// Gets or sets the text.
/// </summary>
/// <value>The text.</value>
public string text { get; set; }
/// <summary>
/// Gets or sets the score.
/// </summary>
/// <value>The score.</value>
public int score { get; set; }
}
/// <summary>
/// Model for twitter trend
/// </summary>
public class Trend
{
/// <summary>
/// Gets or sets the description.
/// </summary>
/// <value>The description.</value>
public TrendDescription description { get; set; }
/// <summary>
/// Gets or sets the first_trended_at.
/// </summary>
/// <value>The first_trended_at.</value>
public DateTime first_trended_at { get; set; }
/// <summary>
/// Gets or sets the last_trended_at.
/// </summary>
/// <value>The last_trended_at.</value>
public DateTime last_trended_at { get; set; }
/// <summary>
/// Gets or sets the name.
/// </summary>
/// <value>The name.</value>
public string name { get; set; }
/// <summary>
/// Gets or sets the newly_trending.
/// </summary>
/// <value>The newly_trending.</value>
public int newly_trending { get; set; }
/// <summary>
/// Gets or sets the query.
/// </summary>
/// <value>The query.</value>
public string query { get; set; }
/// <summary>
/// Gets or sets the trend_index.
/// </summary>
/// <value>The trend_index.</value>
public int trend_index { get; set; }
/// <summary>
/// Gets or sets the URL.
/// </summary>
/// <value>The URL.</value>
public string url { get; set; }
/// <summary>
/// Gets or sets the category_id.
/// </summary>
/// <value>The category_id.</value>
public int category_id { get; set; }
/// <summary>
/// Gets or sets the category_name.
/// </summary>
/// <value>The category_name.</value>
public string category_name { get; set; }
/// <summary>
/// Gets or sets a value indicating whether this <see cref="Trend"/> is locked.
/// </summary>
/// <value><c>true</c> if locked; otherwise, <c>false</c>.</value>
public bool locked { get; set; }
}
/// <summary>
/// Model for trends results
/// </summary>
public class TrendsResults
{
/// <summary>
/// Gets or sets the api_version.
/// </summary>
/// <value>The api_version.</value>
public string api_version { get; set; }
/// <summary>
/// Gets or sets the as_of.
/// </summary>
/// <value>The as_of.</value>
public DateTime as_of { get; set; }
/// <summary>
/// Gets or sets the trends.
/// </summary>
/// <value>The trends.</value>
public Trend[] trends { get; set; }
}
现在我们就可以使用 DataContractJsonSerializer 来将json类型的数据装配到C#对象上。下面是实现解析的代码：
DataContractJsonSerializer dataContractJsonSerializer =
new DataContractJsonSerializer(typeof(TrendsResults));
TrendsResults trendsResults =
(TrendsResults)dataContractJsonSerializer.ReadObject(stream);
new DataContractJsonSerializer(typeof(TrendsResults));
TrendsResults trendsResults =
(TrendsResults)dataContractJsonSerializer.ReadObject(stream);
上面代码中的stream是一个包含json数据的Stream对象。
