JSON可以以“["开头吗? [英] Can JSON start with "["?

问题描述

根据我在

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JSON 文本是一个标记序列.该组令牌包括六个结构字符、字符串、数字和三个字面名称.

JSON 文本是一个序列化的对象或数组.

更新(2014 年)

截至 2014 年 3 月，有一个新的 JSON RFC (7159)稍微修改了定义(参见第 4/5 页).

根据 RFC 4627 的定义是:JSON-text = object/array

这已在 RFC 7159 中更改为:JSON-text = ws value ws

其中ws代表空格，value定义如下:

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JSON 值必须是对象、数组、数字或字符串，或其中之一以下三个字面名称:

false null tr​​ue

所以，这个问题的答案仍然是肯定的，JSON 文本可以以方括号开头(即数组).但除了对象和数组之外，它现在还可以是数字、字符串或值 false、null 或 true.

此外，这与我之前的 RFC 4627 引用有所不同(添加了重点):

<块引用>

JSON 文本是一个标记序列.该组令牌包括六个结构字符、字符串、数字和三个文字名称.

JSON 文本是一个序列化的值.请注意，某些先前的JSON 规范将 JSON 文本限制为对象或大批.仅生成对象或数组的实现要求 JSON 文本将是可互操作的，因为所有实现将接受这些作为符合 JSON 文本.

From what I can read on json.org, all JSON strings should start with { (curly brace), and [ characters (square brackets) represent an array element in JSON.

I use the json4j library, and I got an input that starts with [, so I didn't think this was valid JSON. I looked briefly at the JSON schema, but I couldn't really find it stated that a JSON file cannot start with [, or that it can only start with {.

解决方案

JSON can be either an array or an object. Specifically off of json.org:

JSON is built on two structures:

• A collection of name/value pairs. In various languages, this is realized as an object, record, struct, dictionary, hash table, keyed list, or associative array.
• An ordered list of values. In most languages, this is realized as an
  array, vector, list, or sequence.

It then goes on to describe the two structures as:

Note that the starting and ending characters are curly brackets and square brackets respectively.

Edit
And from here: http://www.ietf.org/rfc/rfc4627.txt

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.

Update (2014)

As of March 2014, there is a new JSON RFC (7159) that modifies the definition slightly (see pages 4/5).

The definition per RFC 4627 was: JSON-text = object / array

This has been changed in RFC 7159 to: JSON-text = ws value ws

Where ws represents whitespace and value is defined as follows:

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

false null true

So, the answer to the question is still yes, JSON text can start with a square bracket (i.e. an array). But in addition to objects and arrays, it can now also be a number, string or the values false, null or true.

Also, this has changed from my previous RFC 4627 quote (emphasis added):

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 value. Note that certain previous specifications of JSON constrained a JSON text to be an object or an array. Implementations that generate only objects or arrays where a JSON text is called for will be interoperable in the sense that all implementations will accept these as conforming JSON texts.

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