[LearnNote] JSON

 

1 JSON

JSON (JavaScript Object Notation) is a lightweight data-interchange format. It is easy for humans to read and write. It is easy for machines to parse and generate.

More information is availble on the home page.

2 JSON in JavaScript

 

2.1 Operate with a JSON object

 

2.1.1 Create a JSON object

// Declare a JSON object (string => array)

var myJSONObject = {"bindings": [

        {"ircEvent": "PRIVMSG", "method": "newURI", "regex": "^http://.*"},

        {"ircEvent": "PRIVMSG", "method": "deleteURI", "regex": "^delete.*"},

        {"ircEvent": "PRIVMSG", "method": "randomURI", "regex": "^random.*"}

    ]

};

2.1.2 Retrieve the members

myJSONObject.bindings[0].method    // "newURI"

2.1.3 Convert a JSON text into an object

Using eval() function

var myObject = eval('(' + myJSONtext + ')');

or using a JSON parser

myData = JSON.parse(text, function (key, value) {

    var type;

    if (value && typeof value === 'object') {

        type = value.type;

        if (typeof type === 'string' && typeof window[type] === 'function') {

            return new (window[type])(value);

        }

    }

    return value;

});

2.1.4 Convert JavaScript data structures into JSON text

function replacer(key, value) {

    if (typeof value === 'number' && !isFinite(value)) {

        return String(value);

    }

    return value;

}



var myJSONText = JSON.stringify(myObject, replacer);

Note: you can use node.js to test this.

3 JSon in C#

 

3.1 Send JSON

// New a object from the anonym class

var serverReadyMsg = new { 

                            req_type = "serverReady",

                            port = int.Parse(System.Environment.GetEnvironmentVariable("channel_port"))

                         };



var client = new TcpClient();

client.Connect(System.Environment.GetEnvironmentVariable("manager_host_name"), int.Parse(System.Environment.GetEnvironmentVariable("manager_port")));



// Serialize the object

JsonSerializerSettings settings = new JsonSerializerSettings();

settings.NullValueHandling = NullValueHandling.Ignore;

string json = JsonConvert.SerializeObject(serverReadyMsg, Formatting.None, settings);



// Prepare the Data   

var memoryStream = new MemoryStream();

memoryStream.SetLength(0);

memoryStream.Position = 0;

// Allocate room for the outgoing size

memoryStream.Write(new byte[] { 0, 0, 0, 0 }, 0, 4);



System.Text.UTF8Encoding encoder = new System.Text.UTF8Encoding();

memoryStream.Write(encoder.GetBytes(json), 0, json.Length);



NetworkStream stream = client.GetStream();



Byte[] bytes = BitConverter.GetBytes((uint)(memoryStream.Length - 4));

Byte[] outArray = memoryStream.ToArray();

bytes.CopyTo(outArray, 0);

stream.Write(outArray, 0, (int)memoryStream.Length);

stream.Flush();

3.2 Parser JSON

string receivedString = string.Empty;

System.Text.UTF8Encoding encoder = new System.Text.UTF8Encoding();

System.Text.Decoder utf8Decode = encoder.GetDecoder();

try

{

    int receivedBufferSize = tcpClient.ReceiveBufferSize;

    if (receivedBufferSize > 0)

    {

        // Retrieve the data from the socket

        byte[] data = new byte[receivedBufferSize];

  

        int dataLength = tcpClient.GetStream().Read(data, 0, data.Length);

  

        char[] receivedChars = new char[dataLength - 4];

        utf8Decode.GetChars(data, 4, dataLength - 4, receivedChars, 0, true);

        receivedString = new String(receivedChars);

  

        // Use Linq to JSON to parse the input

        JObject jobject = JObject.Parse(receivedString);

        JToken token = jobject["req_type"];

  

        string req_type = (string)token;

        

        // Dispatch the request

        switch (req_type)

        {

            case "newServerInstance":

                break;

            case "deleteServerInstance":

                break;

            case "serverReady":

                break;

        }

    }

}

catch (System.IO.IOException)

{

}

3.3 Linq to JSon

Code snippet from : http://blog.csdn.net/zhoufoxcn/article/details/6254657

public static void JsonConvertLinqDemo()  

{  

    User user = new User { UserId = 1, UserName = "周公", CreateDate = DateTime.Now.AddYears(-8), Birthday = DateTime.Now.AddYears(-32), Priority = Priority.Lowest, Salary = 500, Urls = new List<string> { "http://zhoufoxcn.blog.51cto.com", "http://blog.csdn.net/zhoufoxcn" } };  

    //JsonConvert类在Newtonsoft.Json.Net35.dll中，注意到http://www.codeplex.com/json/下载这个dll并添加这个引用  

    //JSON序列化  

    string result = JsonConvert.SerializeObject(user);  

    Console.WriteLine("使用JsonConvert序列化后的结果：{0},长度：{1}", result, result.Length);  

    //使用Linq to JSON  

    JObject jobject = JObject.Parse(result);  

    JToken token = jobject["Urls"];  

    List<string> urlList = new List<string>();  

    foreach (JToken t in token)  

    {  

        urlList.Add(t.ToString());  

    }  

    Console.Write("使用Linq to JSON反序列化后的结果：[");  

    for (int i = 0; i < urlList.Count - 1;i++ )  

    {  

        Console.Write(urlList[i] + ",");  

    }  

    Console.WriteLine(urlList[urlList.Count - 1] + "]");  

}

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Post by: Jalen Wang (转载请注明出处)