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JSON数据交换标准-英文版

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JSON是目前最主流的网络应用数据交换格式,也可以说是目前最主流的数据交换标准,我们现在的很多网站和移动端APP应用,如果需要调取外部数据,规范的讲用JSON做接口最为合适,几乎说包括asp、php甚至于vb 的所有语言都支持json接口的方式传递数据。

JSON简介:

JSON(JavaScript Object Notation) 是一种轻量级的数据交换格式。它使得人们很容易的进行阅读和编写。同时也方便了机器进行解析和生成。它是基于 JavaScript Programming Language , Standard ECMA-262 3rd Edition - December 1999 的一个子集。 JSON采用完全独立于程序语言的文本格式,但是也使用了类C语言的习惯(包括C, C++, C#, Java, JavaScript, Perl, Python等)。这些特性使JSON成为理想的数据交换语言。
JSON基于两种结构:
“名称/值”对的集合(A collection of name/value pairs)。不同的编程语言中,它被理解为对象(object),纪录(record),结构(struct),字典(dictionary),哈希表(hash table),有键列表(keyed list),或者关联数组 (associative array)。
值的有序列表(An ordered list of values)。在大部分语言中,它被实现为数组(array),矢量(vector),列表(list),序列(sequence)。
这些都是常见的数据结构。目前,绝大部分编程语言都以某种形式支持它们。这使得在各种编程语言之间交换同样格式的数据成为可能。
JSON具有以下这些形式:
对象(object) 是一个无序的“‘名称/值’对”集合。一个对象以“{”(左括号)开始,“}”(右括号)结束。每个“名称”后跟一个“:”(冒号);“‘名称/值’ 对”之间使用“,”(逗号)分隔。
JSON 对象
数组(array) 是值(value)的有序集合。一个数组以“[”(左中括号)开始,“]”(右中括号)结束。值之间使用“,”(逗号)分隔。
JSON 数组
值(value) 可以是双引号括起来的字符串(string)、数值(number)、true、false、 null、对象(object)或者数组(array)。这些结构可以嵌套。
JSON 值
字符串(string) 是由双引号包围的任意数量Unicode字符的集合,使用反斜线转义。一个字符(character)即一个单独的字符串(character string)。
JSON的字符串(string)与C或者Java的字符串非常相似。
JSON 字符串
数值(number) 也与C或者Java的数值非常相似。只是JSON的数值没有使用八进制与十六进制格式。
JSON 数值
同时,可以在任意标记之间添加空白。
JSON数据交换标准英文版:

Network Working Group D. Crockford
Request for Comments: 4627 JSON.org
Category: Informational July 2006

The application/json Media Type for JavaScript Object Notation (JSON)

Status of This Memo

This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.

Copyright Notice

Copyright (C) The Internet Society (2006).

Abstract

JavaScript Object Notation (JSON) is a lightweight, text-based,
language-independent data interchange format. It was derived from
the ECMAScript Programming Language Standard. JSON defines a small
set of formatting rules for the portable representation of structured
data.

1. Introduction

JavaScript Object Notation (JSON) is a text format for the
serialization of structured data. It is derived from the object
literals of JavaScript, as defined in the ECMAScript Programming
Language Standard, Third Edition [ECMA].

JSON can represent four primitive types (strings, numbers, booleans,
and null) and two structured types (objects and arrays).

A string is a sequence of zero or more Unicode characters [UNICODE].

An object is an unordered collection of zero or more name/value
pairs, where a name is a string and a value is a string, number,
boolean, null, object, or array.

An array is an ordered sequence of zero or more values.

The terms "object" and "array" come from the conventions of
JavaScript.

JSON's design goals were for it to be minimal, portable, textual, and
a subset of JavaScript.

Crockford Informational [Page 1]

RFC 4627 JSON July 2006

1.1. Conventions Used in This Document

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].

The grammatical rules in this document are to be interpreted as
described in [RFC4234].

2. JSON Grammar

A JSON text is a sequence of tokens. The set of tokens includes six
structural characters, strings, numbers, and three literal names.

A JSON text is a serialized object or array.

JSON-text = object / array

These are the six structural characters:

begin-array = ws %x5B ws ; [ left square bracket

begin-object = ws %x7B ws ; { left curly bracket

end-array = ws %x5D ws ; ] right square bracket

end-object = ws %x7D ws ; } right curly bracket

name-separator = ws %x3A ws ; : colon

value-separator = ws %x2C ws ; , comma

Insignificant whitespace is allowed before or after any of the six
structural characters.

ws = *(
%x20 / ; Space
%x09 / ; Horizontal tab
%x0A / ; Line feed or New line
%x0D ; Carriage return
)

2.1. Values

A JSON value MUST be an object, array, number, or string, or one of
the following three literal names:

false null true

Crockford Informational [Page 2]

RFC 4627 JSON July 2006

The literal names MUST be lowercase. No other literal names are
allowed.

value = false / null / true / object / array / number / string

false = %x66.61.6c.73.65 ; false

null = %x6e.75.6c.6c ; null

true = %x74.72.75.65 ; true

2.2. Objects

An object structure is represented as a pair of curly brackets
surrounding zero or more name/value pairs (or members). A name is a
string. A single colon comes after each name, separating the name
from the value. A single comma separates a value from a following
name. The names within an object SHOULD be unique.

object = begin-object [ member *( value-separator member ) ]
end-object

member = string name-separator value

2.3. Arrays

An array structure is represented as square brackets surrounding zero
or more values (or elements). Elements are separated by commas.

array = begin-array [ value *( value-separator value ) ] end-array

2.4. Numbers

The representation of numbers is similar to that used in most
programming languages. A number contains an integer component that
may be prefixed with an optional minus sign, which may be followed by
a fraction part and/or an exponent part.

Octal and hex forms are not allowed. Leading zeros are not allowed.

A fraction part is a decimal point followed by one or more digits.

An exponent part begins with the letter E in upper or lowercase,
which may be followed by a plus or minus sign. The E and optional
sign are followed by one or more digits.

Numeric values that cannot be represented as sequences of digits
(such as Infinity and NaN) are not permitted.

Crockford Informational [Page 3]

RFC 4627 JSON July 2006

number = [ minus ] int [ frac ] [ exp ]

decimal-point = %x2E ; .

digit1-9 = %x31-39 ; 1-9

e = %x65 / %x45 ; e E

exp = e [ minus / plus ] 1*DIGIT

frac = decimal-point 1*DIGIT

int = zero / ( digit1-9 *DIGIT )

minus = %x2D ; -

plus = %x2B ; +

zero = %x30 ; 0

2.5. Strings

The representation of strings is similar to conventions used in the C
family of programming languages. A string begins and ends with
quotation marks. All Unicode characters may be placed within the
quotation marks except for the characters that must be escaped:
quotation mark, reverse solidus, and the control characters (U+0000
through U+001F).

Any character may be escaped. If the character is in the Basic
Multilingual Plane (U+0000 through U+FFFF), then it may be
represented as a six-character sequence: a reverse solidus, followed
by the lowercase letter u, followed by four hexadecimal digits that
encode the character's code point. The hexadecimal letters A though
F can be upper or lowercase. So, for example, a string containing
only a single reverse solidus character may be represented as
"\u005C".

Alternatively, there are two-character sequence escape
representations of some popular characters. So, for example, a
string containing only a single reverse solidus character may be
represented more compactly as "\\".

To escape an extended character that is not in the Basic Multilingual
Plane, the character is represented as a twelve-character sequence,
encoding the UTF-16 surrogate pair. So, for example, a string
containing only the G clef character (U+1D11E) may be represented as
"\uD834\uDD1E".

Crockford Informational [Page 4]

RFC 4627 JSON July 2006

string = quotation-mark *char quotation-mark

char = unescaped /
escape (
%x22 / ; " quotation mark U+0022
%x5C / ; \ reverse solidus U+005C
%x2F / ; / solidus U+002F
%x62 / ; b backspace U+0008
%x66 / ; f form feed U+000C
%x6E / ; n line feed U+000A
%x72 / ; r carriage return U+000D
%x74 / ; t tab U+0009
%x75 4HEXDIG ) ; uXXXX U+XXXX

escape = %x5C ; \

quotation-mark = %x22 ; "

unescaped = %x20-21 / %x23-5B / %x5D-10FFFF

3. Encoding

JSON text SHALL be encoded in Unicode. The default encoding is
UTF-8.

Since the first two characters of a JSON text will always be ASCII
characters [RFC0020], it is possible to determine whether an octet
stream is UTF-8, UTF-16 (BE or LE), or UTF-32 (BE or LE) by looking
at the pattern of nulls in the first four octets.

00 00 00 xx UTF-32BE
00 xx 00 xx UTF-16BE
xx 00 00 00 UTF-32LE
xx 00 xx 00 UTF-16LE
xx xx xx xx UTF-8

4. Parsers

A JSON parser transforms a JSON text into another representation. A
JSON parser MUST accept all texts that conform to the JSON grammar.
A JSON parser MAY accept non-JSON forms or extensions.

An implementation may set limits on the size of texts that it
accepts. An implementation may set limits on the maximum depth of
nesting. An implementation may set limits on the range of numbers.
An implementation may set limits on the length and character contents
of strings.

Crockford Informational [Page 5]

RFC 4627 JSON July 2006

5. Generators

A JSON generator produces JSON text. The resulting text MUST
strictly conform to the JSON grammar.

6. IANA Considerations

The MIME media type for JSON text is application/json.

Type name: application

Subtype name: json

Required parameters: n/a

Optional parameters: n/a

Encoding considerations: 8bit if UTF-8; binary if UTF-16 or UTF-32

JSON may be represented using UTF-8, UTF-16, or UTF-32. When JSON
is written in UTF-8, JSON is 8bit compatible. When JSON is
written in UTF-16 or UTF-32, the binary content-transfer-encoding
must be used.

Security considerations:

Generally there are security issues with scripting languages. JSON
is a subset of JavaScript, but it is a safe subset that excludes
assignment and invocation.

A JSON text can be safely passed into JavaScript's eval() function
(which compiles and executes a string) if all the characters not
enclosed in strings are in the set of characters that form JSON
tokens. This can be quickly determined in JavaScript with two
regular expressions and calls to the test and replace methods.

var my_JSON_object = !(/[^,:{}\[\]0-9.\-+Eaeflnr-u \n\r\t]/.test(
text.replace(/"(\\.|[^"\\])*"/g, ''))) &&
eval('(' + text + ')');

Interoperability considerations: n/a

Published specification: RFC 4627

Crockford Informational [Page 6]

RFC 4627 JSON July 2006

Applications that use this media type:

JSON has been used to exchange data between applications written
in all of these programming languages: ActionScript, C, C#,
ColdFusion, Common Lisp, E, Erlang, Java, JavaScript, Lua,
Objective CAML, Perl, PHP, Python, Rebol, Ruby, and Scheme.

Additional information:

Magic number(s): n/a
File extension(s): .json
Macintosh file type code(s): TEXT

Person & email address to contact for further information:
Douglas Crockford
douglas@crockford.com

Intended usage: COMMON

Restrictions on usage: none

Author:
Douglas Crockford
douglas@crockford.com

Change controller:
Douglas Crockford
douglas@crockford.com

7. Security Considerations

See Security Considerations in Section 6.

8. Examples

This is a JSON object:

{
"Image": {
"Width": 800,
"Height": 600,
"Title": "View from 15th Floor",
"Thumbnail": {
"Url": "http://www.example.com/image/481989943",
"Height": 125,
"Width": "100"
},
"IDs": [116, 943, 234, 38793]

Crockford Informational [Page 7]

RFC 4627 JSON July 2006

}
}

Its Image member is an object whose Thumbnail member is an object
and whose IDs member is an array of numbers.

This is a JSON array containing two objects:

[
{
"precision": "zip",
"Latitude": 37.7668,
"Longitude": -122.3959,
"Address": "",
"City": "SAN FRANCISCO",
"State": "CA",
"Zip": "94107",
"Country": "US"
},
{
"precision": "zip",
"Latitude": 37.371991,
"Longitude": -122.026020,
"Address": "",
"City": "SUNNYVALE",
"State": "CA",
"Zip": "94085",
"Country": "US"
}
]

9. References

9.1. Normative References

[ECMA] European Computer Manufacturers Association, "ECMAScript
Language Specification 3rd Edition", December 1999,
<http://www.ecma-international.org/publications/files/
ecma-st/ECMA-262.pdf>.

[RFC0020] Cerf, V., "ASCII format for network interchange", RFC 20,
October 1969.

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.

[RFC4234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 4234, October 2005.

Crockford Informational [Page 8]

RFC 4627 JSON July 2006

[UNICODE] The Unicode Consortium, "The Unicode Standard Version 4.0",
2003, <http://www.unicode.org/versions/Unicode4.1.0/>.

Author's Address

Douglas Crockford
JSON.org
EMail: douglas@crockford.com

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