JSON.NET与LINQ序列化示例

刺骨的言语ヽ痛彻心扉 2021-06-26 16:06 332阅读 0赞

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，总结都是`JSON.NET`与`LINQ`结合的常用示例，希望对您有所帮助。