在上一篇博客中,我们演示了JSON.NET提供的最基础功能,这篇文章通过多个示例演示JSON.NET与LINQ的完美结合,让.NET操作JSON变得非常的简单,最后我们还会演示如何通过JSON.NET转换BSON数据、如何实现JSON格式与XML格式的互相转换,让您熟练在.NET中序列化对象。
1、手动创建JSON对象和数组
JSON格式主要包括对象和数组两种形式,在JSON.NET中分别用JArray和JObject表示,属性用JProperty表示,属性值用JValue表示,这些对象都直接或间接继承JToken抽象类,而且都有一个ToString方法,该方法用于直接输出元素的JSON字符串表示形式,我们可以通过JArray和JObject手动创建JSON并序列化,使用方式非常灵活。
JArray array = new JArray(); array.Add("Manual text"); array.Add(new DateTime(2000, 5, 23)); JObject o = new JObject(); o["MyArray"] = array; string json = o.ToString();
{
"MyArray": [
"Manual text",
"2000-05-23T00:00:00"
]
}
2、用集合的方式初始化JArray数组和JObject对象
JObject o = new JObject { { "Cpu", "Intel" }, { "Memory", 32 }, { "Drives", new JArray { "DVD", "SSD" } } }; Console.WriteLine(o.ToString());
{
"Cpu": "Intel",
"Memory": 32,
"Drives": [
"DVD",
"SSD"
]
}
3、使用动态类型dynamic类型创建JSON数组和对象
C#中的动态类型dynamic允许开发者动态构造对象,这些动态构造的对象在运行时被解析执行,JSON.NET支持动态类型,无需定义类,即可构造JSON,这一些就像在JavaScript中编写一个对象那样简单,正是因为动态类型在运行时才被解析,所以,在开发工具中不能检查因书写而导致错误,这点一定要注意。
dynamic product = new JObject(); product.ProductName = "Elbow Grease"; product.Enabled = true; product.Price = 4.90m; product.StockCount = 9000; product.StockValue = 44100; product.Tags = new JArray("Real", "OnSale"); Console.WriteLine(product.ToString());
{
"ProductName": "Elbow Grease",
"Enabled": true,
"Price": 4.90,
"StockCount": 9000,
"StockValue": 44100,
"Tags": [
"Real",
"OnSale"
]
}
4、使用JTokenWriter创建对象和数组
JTokenWriter writer = new JTokenWriter(); writer.WriteStartObject(); writer.WritePropertyName("name1"); writer.WriteValue("value1"); writer.WritePropertyName("name2"); writer.WriteStartArray(); writer.WriteValue(1); writer.WriteValue(2); writer.WriteEndArray(); writer.WriteEndObject(); JObject o = (JObject)writer.Token; Console.WriteLine(o.ToString());
{
"name1": "value1",
"name2": [
1,
2
]
}
5、使用对象创建JSON对象和数组
JToken、JObject和JArray都提供一个名为FromObject的方法,允许通过一个对象来创建JSON对象。
Computer computer = new Computer { Cpu = "Intel", Memory = 32, Drives = new List<string> { "DVD", "SSD" } }; JObject o = (JObject)JToken.FromObject(computer); Console.WriteLine(o.ToString());
{
"Cpu": "Intel",
"Memory": 32,
"Drives": [
"DVD",
"SSD"
]
}
JArray a = (JArray)JToken.FromObject(computer.Drives); Console.WriteLine(a.ToString());
[
"DVD",
"SSD"
]
6、使用字符串创建JSON对象和数组
string json = @"['Small', 'Medium','Large']"; JArray a = JArray.Parse(json); Console.WriteLine(a.ToString());
[
"Small",
"Medium",
"Large"
]
string json = @"{ CPU: 'Intel', Drives: [ 'DVD read/writer', '500 gigabyte hard drive' ] }"; JObject o = JObject.Parse(json); Console.WriteLine(o.ToString());
{
"CPU": "Intel",
"Drives": [
"DVD read/writer",
"500 gigabyte hard drive"
]
}
7、使用JToken转换JSON字符串
在示例1中,我们已经说明JToken类型,它是JSON.NET的核心,几乎所有的JSON元素都继承于JToken抽象类,虽然JToken是抽象类,但它也提供一些很有用的基础方法,可以转换一段字符串并判断它应有的JSON类型。
JToken t1 = JToken.Parse("{}"); Console.WriteLine(t1.Type); // Object JToken t2 = JToken.Parse("[]"); Console.WriteLine(t2.Type); // Array JToken t3 = JToken.Parse("null"); Console.WriteLine(t3.Type); // Null JToken t4 = JToken.Parse(@"'A string!'"); Console.WriteLine(t4.Type); // String
8、动态修改JSON对象和数组
string json = @"{ 'channel': { 'title': 'Star Wars', 'link': 'www.xcode.me', 'description': 'Star Wars blog.', 'obsolete': 'Obsolete value', 'item': [] } }"; JObject rss = JObject.Parse(json); JObject channel = (JObject)rss["channel"]; channel["title"] = ((string)channel["title"]).ToUpper(); channel["description"] = ((string)channel["description"]).ToUpper(); channel.Property("obsolete").Remove(); channel.Property("description").AddAfterSelf(new JProperty("new", "New value")); JArray item = (JArray)channel["item"]; item.Add("Item 1"); item.Add("Item 2"); Console.WriteLine(rss.ToString());
{
"channel": {
"title": "STAR WARS",
"link": "www.xcode.com",
"description": "STAR WARS BLOG.",
"new": "New value",
"item": [
"Item 1",
"Item 2"
]
}
}
9、合并两个JSON对象
JObject o1 = JObject.Parse(@"{ 'FirstName': 'John', 'LastName': 'Smith', 'Enabled': false, 'Roles': [ 'User' ] }"); JObject o2 = JObject.Parse(@"{ 'Enabled': true, 'Roles': [ 'User', 'Admin' ] }"); o1.Merge(o2, new JsonMergeSettings { MergeArrayHandling = MergeArrayHandling.Union }); string json = o1.ToString();
{
"FirstName": "John",
"LastName": "Smith",
"Enabled": true,
"Roles": [
"User",
"Admin"
]
}
这里要特别说明的是JsonMergeSettings,该对象用于设置合并时的行为,MergeArrayHandling是枚举,可设置为Concat(连接数组)、Union(跳过存在的元素,添加不存在的元素)、Replace(替换所有数组项)和Merge(根据数组索引将数组项合并在一起)。
10、使用动态类型dynamic查询JSON对象
string json = @"[ { 'Title': 'Json.NET is awesome!', 'Author': { 'Name': 'James Newton-King', 'Twitter': '@JamesNK', 'Picture': '/jamesnk.png' }, 'Date': '2013-01-23T19:30:00' } ]"; dynamic blogPosts = JArray.Parse(json); dynamic blogPost = blogPosts[0]; Console.WriteLine(blogPost.Title);
Json.NET is awesome!
11、使用ToObject将JSON对象或数组转换成C#对象
string json = @"{ 'd': [ { 'Name': 'John Smith' }, { 'Name': 'Mike Smith' } ] }"; JObject o = JObject.Parse(json); JArray a = (JArray)o["d"]; IList<Person> person = a.ToObject<IList<Person>>(); Console.WriteLine(person[1].Name);
Mike Smith
12、通过属性遍历JObject对象
JObject o = new JObject { { "name1", "value1" }, { "name2", "value2" } }; foreach (JProperty property in o.Properties()) { Console.WriteLine(property.Name + " - " + property.Value); }
name1 - value1
name2 - value2
foreach (KeyValuePair<string, JToken> property in o) { Console.WriteLine(property.Key + " - " + property.Value); }
name1 - value1
name2 - value2
13、使用ToString方法进行JSON序列化
在JSON.NET中ToString方法会输出针对当前JSON对象的字符串表示形式,通过这个特点我们可以序列化对象,默认情况下会输出格式化后的JSON字符串,ToString方法提供一些重载,允许开发灵活配置序列化行为。
JObject o = JObject.Parse(@"{'string1':'value','integer2':99,'datetime3':'2000-05-23T00:00:00'}"); Console.WriteLine(o.ToString());
{
"string1": "value",
"integer2": 99,
"datetime3": "2000-05-23T00:00:00"
}
ToString方法也提供一个是否格式化重载方法,下面的示例演示输出压缩后的JSON字符串。
Console.WriteLine(o.ToString(Formatting.None));
{"string1":"value","integer2":99,"datetime3":"2000-05-23T00:00:00"}
下面的代码演示通过ToString方法提供的重载将日期格式化为JavaScript中的日期对象,这样的JSON在JS中就可以直接使用日期。
Console.WriteLine(o.ToString(Formatting.None, new JavaScriptDateTimeConverter()));
{"string1":"value","integer2":99,"datetime3":new Date(959032800000)}
14、JSON.NET支持BSON格式的序列化和反序列化
BSON是一种类似于JSON格式,是一种二进制形式存储格式,简称BinaryJSON,它和JSON一样,支持内嵌的对象和数组,BSON可以做为网络数据交换的一种存储形式,它的优点是灵活性高,但它的缺点是空间利用率不是很理想,JSON.NET也支持BSON的序列化和反序列化。
byte[] data = Convert.FromBase64String("KQAAAAJuYW1lMQAHAAAAdmFsdWUxAAJuYW1lMgAHAAAAdmFsdWUyAAA="); MemoryStream ms = new MemoryStream(data); JObject o; using (BsonReader reader = new BsonReader(ms)) { o = (JObject)JToken.ReadFrom(reader); } string value = (string)o["name1"]; Console.WriteLine(value);
value1
JObject o = new JObject { { "name1", "value1" }, { "name2", "value2" } }; MemoryStream ms = new MemoryStream(); using (BsonWriter writer = new BsonWriter(ms)) { o.WriteTo(writer); } string data = Convert.ToBase64String(ms.ToArray()); Console.WriteLine(data);
KQAAAAJuYW1lMQAHAAAAdmFsdWUxAAJuYW1lMgAHAAAAdmFsdWUyAAA=
15、JSON.NET也支持JSON与XML数据格式之间的互转
string json = @"{ '@Id': 1, 'Email': 'james@example.com', 'Active': true, 'CreatedDate': '2013-01-20T00:00:00Z', 'Roles': [ 'User', 'Admin' ], 'Team': { '@Id': 2, 'Name': 'Software Developers', 'Description': 'Creators of fine software products and services.' } }"; XNode node = JsonConvert.DeserializeXNode(json, "Root"); Console.WriteLine(node.ToString());
<Root Id="1">
<Email>james@example.com</Email>
<Active>true</Active>
<CreatedDate>2013-01-20T00:00:00Z</CreatedDate>
<Roles>User</Roles>
<Roles>Admin</Roles>
<Team Id="2">
<Name>Software Developers</Name>
<Description>Creators of fine software products and services.</Description>
</Team>
</Root>
string xml = @"<?xml version='1.0' standalone='no'?> <root> <person id='1'> <name>Alan</name> <url>www.xocde.me</url> </person> <person id='2'> <name>Louis</name> <url>www.xocde.me</url> </person> </root>"; XmlDocument doc = new XmlDocument(); doc.LoadXml(xml); string json = JsonConvert.SerializeXmlNode(doc); Console.WriteLine(json);
{
"?xml": {
"@version": "1.0",
"@standalone": "no"
},
"root": {
"person": [
{
"@id": "1",
"name": "Alan",
"url": "www.xocde.me"
},
{
"@id": "2",
"name": "Louis",
"url": "www.xocde.me"
}
]
}
}
当然,JSON.NET框架很强大,功能也很多,零度总结都是JSON.NET与LINQ结合的常用示例,希望对您有所帮助。