JSON可以以"["开头吗? [英] Can JSON start with "["?
问题描述
根据我在 json.org 上可以看到的内容，所有JSON字符串都应以{开头(大括号)和[字符(方括号)表示JSON中的数组元素.
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.
我使用json4j库，并且得到了以[开头的输入，因此我认为这不是有效的JSON.我简要地看了一下JSON模式，但是我找不到它表明JSON文件不能以[开头，或者只能以{开头.
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 {.
推荐答案
JSON可以是数组或对象.专门针对json.org:
JSON can be either an array or an object. Specifically off of json.org:
JSON建立在两个结构上:
JSON is built on two structures:
- 名称/值对的集合.在各种语言中，这是 实现为一个对象，记录， 结构，字典，哈希表， 键列表或关联数组.
- 值的有序列表.在大多数语言中，这是通过
数组，向量，列表或序列.
- 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.
然后继续将这两种结构描述为:
It then goes on to describe the two structures as:
请注意，起始字符和结束字符分别是大括号和方括号.
Note that the starting and ending characters are curly brackets and square brackets respectively.
修改
从这里开始: http://www.ietf.org/rfc/rfc4627.txt
Edit
And from here: http://www.ietf.org/rfc/rfc4627.txt
JSON文本是令牌序列. 令牌集包括六个 结构字符，字符串， 数字和三个文字名称.
A JSON text is a sequence of tokens. The set of tokens includes six structural characters, strings, numbers, and three literal names.
JSON文本是序列化的对象或数组.
A JSON text is a serialized object or array.
更新(2014)
截至2014年3月，有一个新的JSON RFC( 7159 )会稍微修改定义(请参阅第4/5页).
Update (2014)
As of March 2014, there is a new JSON RFC (7159) that modifies the definition slightly (see pages 4/5).
根据RFC 4627的定义是:JSON-text = object / array
The definition per RFC 4627 was: JSON-text = object / array
在RFC 7159中已将其更改为:JSON-text = ws value ws
This has been changed in RFC 7159 to: JSON-text = ws value ws
其中ws表示空格，而value定义如下:
Where ws represents whitespace and value is defined as follows:
JSON值必须是对象，数组，数字或字符串，或者是以下之一 以下三个文字名称:
A JSON value MUST be an object, array, number, or string, or one of the following three literal names:
false null true
因此，问题的答案仍然是，JSON文本可以以方括号(即数组)开头.但是，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.
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.
此外，这与我以前的RFC 4627引用(添加了重点)有所不同:
Also, this has changed from my previous RFC 4627 quote (emphasis added):
JSON文本是令牌序列.令牌集包括六个 结构字符，字符串，数字和三个文字名称.
A JSON text is a sequence of tokens. The set of tokens includes six structural characters, strings, numbers, and three literal names.
JSON文本是序列化的值.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，其中 JSON文本将在所有意义上都可互操作 实现将接受这些作为符合条件的JSON文本.
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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