JSON Learning Notes

　　　　　　　　　　　　　　Json

Full Name:--javascript object notation. (JavaScript Object Notation)

Official website: www.json.org

Description: Both JSON and XML are used for data transfer, they are small and convenient and easy to interact with JavaScript

File type of files: " . JSON "

MIME type of text: "application/json"

Conditions of Use: Import related package Net.sf.json{

Commons-beanutils-1.7.0.jar

Commons-collection-3.1.jar

Commons-lang-2.5.jar

Commons-logging.jar

Ezmorph-1.0.6.jar

Json-lib-2.4-jdk15.jar

}

Package of Baidu Cloud Link: (To fill)

I. Basic information of JSON

1. He is a lightweight text data interchange format.

2. In syntax, JSON syntax is a subset of JavaScript syntax

{It uses JavaScript syntax to describe the data object, which is syntactically identical to the code that created the JavaScript object and can be parsed directly from JavaScript

( Note:JavaScript programs can use the built-in eval () function to generate native JavaScript objects with JSON data.) )

}

3.JSON data can be transmitted using AJAX.

4.JSON VS XML (comparison of JSON versus XML)

	json	XML
data readability	Same	same
analytic means /span>	also rich	also rich
data volume	small td>	large
interaction with JavaScript	more convenient
Descriptive of the data	poor	good

Two. Syntax rules for JSON

1. Data format: "Variable name": value, such as: "FirstName": "John"

2. Object: Save,--> {} with curly braces

3. Array: Save,--> in square brackets []

4. Data separation: comma (comma),-->,

Three. JSON data type (6 types)

1. Null (NULL)--NULL

2. Boolean value (Boolean)-->true/false

3. Numeric value (number) and direct data

4. Strings (string)--"strings"

5. Arrays (array)--[content]

6. Objects (object)---{Object Properties}

Notes

1. The array can contain multiple objects, such as:

　　　　

That is, the object employees has three sub-objects, each of which has two properties

）

Four. Alternative assignment methods for JSON

1. Using JavaScript to assign values, such as:

1 var employees = [2 {"FirstName": "Bill", "LastName": "Gates"},3 {" FirstName ":" Json "," LastName ":" Well "}4]; 5 // Accessing Data 6 // Back to Gates 7 // Modifying Data 8 employees[0].lastname = "Gall";

Five. Object conversion between JSON and JavaScript

1.JSONObject Objects --Convert----> (#3bc359) JavaScript

One of the most common usages of--json.

-- That is, the JSON data is read from the Web server (as a file or as a httprequest), and the JSON the data is converted to a JavaScript object, and then the data is used in the Web page.

　　(pending)

2.JavaScript Object--Convert---->jsonobject object

　　　　(pending)

　　3. Using JavaScript objects

<P>FirstName:<spanID= "FName"></span><BR/>LastName:<spanID= "LName"></span><BR/></P><Scripttype= "Text/javascript">document.getElementById ("fname"). InnerHTML=obj.employees[0].firstname; document.getElementById ("lname"). InnerHTML=obj.employees[0].lastname;</Script>

Six. Conversion between Jsonobject and map<string,string>

(pending)

JSON Learning Notes