jsonpath - 通过表达式解析 JSON
JSONPath 之于 JSON，就如 XPath 之于 XML。JSONPath 可以方便对 JSON 数据结构进行内容提取。[1]
根对象使用 $ 来表示，而无需区分是对象还是数组。
表达式可以使用 .，也可以使用 []。如：
$.store.book[0].title 或 $['store']['book'][0]['title']。
表达式 (<expr>) 可用作显式名称或索引的替代，如：
$.store.book[(@.length-1)].title 表示获取最后一个 book 的 title。
使用符号 @ 表示当前对象。过滤器表达式通过语法支持，?(<boolean expr>) 如：
$.store.book[?(@.price < 10)].title 表示获取价格小于 10 的所有 book 的 title。
要点
$表示文档的根元素@表示文档的当前元素.node_name或['node_name']匹配下级节点[index]检索数组中的元素[start:end:step]支持数组切片语法*作为通配符，匹配所有成员..子递归通配符，匹配成员的所有子元素(<expr>)使用表达式?(<boolean expr>)进行数据筛选
JsonPath 是一种用于从 JSON 数据中提取信息的语言。它类似于 XPath，但是专门用于 JSON 数据。以下是 JsonPath 的语法：
$：表示根节点。@：表示当前节点。.：表示子节点。..：表示子孙节点。*：表示通配符，匹配任意节点。[]：表示索引，可以匹配数组中的元素或对象中的属性。[,]：表示多索引，可以同时匹配多个索引。[:n]：表示从第一个元素开始到第 n 个元素。[-n:]：表示从倒数第 n 个元素开始到最后一个元素。[start:end:step]：表示从第 start 个元素开始到第 end 个元素，步长为 step。
下面是几个示例：
假设我们有以下 JSON 数据：
{
"store": {
"book": [
{
"category": "reference",
"author": "Nigel Rees",
"title": "Sayings of the Century",
"price": 8.95
},
{
"category": "fiction",
"author": "Evelyn Waugh",
"title": "Sword of Honour",
"price": 12.99
},
{
"category": "fiction",
"author": "Herman Melville",
"title": "Moby Dick",
"isbn": "0-553-21311-3",
"price": 8.99
},
{
"category": "fiction",
"author": "J. R. R. Tolkien",
"title": "The Lord of the Rings",
"isbn": "0-395-19395-8",
"price": 22.99
}
],
"bicycle": {
"color": "red",
"price": 19.95
}
}
}
$：表示整个 JSON 数据。
{
"store": {
"book": [
{
"category": "reference",
"author": "Nigel Rees",
"title": "Sayings of the Century",
"price": 8.95
},
{
"category": "fiction",
"author": "Evelyn Waugh",
"title": "Sword of Honour",
"price": 12.99
},
{
"category": "fiction",
"author": "Herman Melville",
"title": "Moby Dick",
"isbn": "0-553-21311-3",
"price": 8.99
},
{
"category": "fiction",
"author": "J. R. R. Tolkien",
"title": "The Lord of the Rings",
"isbn": "0-395-19395-8",
"price": 22.99
}
],
"bicycle": {
"color": "red",
"price": 19.95
}
}
}
$.store：表示 store 对象。
{
"book": [
{
"category": "reference",
"author": "Nigel Rees",
"title": "Sayings of the Century",
"price": 8.95
},
{
"category": "fiction",
"author": "Evelyn Waugh",
"title": "Sword of Honour",
"price": 12.99
},
{
"category": "fiction",
"author": "Herman Melville",
"title": "Moby Dick",
"isbn": "0-553-21311-3",
"price": 8.99
},
{
"category": "fiction",
"author": "J. R. R. Tolkien",
"title": "The Lord of the Rings",
"isbn": "0-395-19395-8",
"price": 22.99
}
],
"bicycle": {
"color": "red",
"price": 19.95
}
}
$.store.book[*]：表示所有书籍。
[
{
"category": "reference",
"author": "Nigel Rees",
"title": "Sayings of the Century",
"price": 8.95
},
{
"category": "fiction",
"author": "Evelyn Waugh",
"title": "Sword of Honour",
"price": 12.99
},
{
"category": "fiction",
"author": "Herman Melville",
"title": "Moby Dick",
"isbn": "0-553-21311-3",
"price": 8.99
},
{
"category": "fiction",
"author": "J. R. R. Tolkien",
"title": "The Lord of the Rings",
"isbn": "0-395-19395-8",
"price": 22.99
}
]
$.store.book[2]：表示第三本书（索引从 0 开始）。
{
"category": "fiction",
"author": "Herman Melville",
"title": "Moby Dick",
"isbn": "0-553-21311-3",
"price": 8.99
}
$.store.book[-2:]：表示最后两本书。
[
{
"category": "fiction",
"author": "Herman Melville",
"title": "Moby Dick",
"isbn": "0-553-21311-3",
"price": 8.99
},
{
"category": "fiction",
"author": "J. R. R. Tolkien",
"title": "The Lord of the Rings",
"isbn": "0-395-19395-8",
"price": 22.99
}
]
$.store.book[0,2]：表示第一本和第三本书。
[
{
"category": "reference",
"author": "Nigel Rees",
"title": "Sayings of the Century",
"price": 8.95
},
{
"category": "fiction",
"author": "Herman Melville",
"title": "Moby Dick",
"isbn": "0-553-21311-3",
"price": 8.99
}
]
$.store.book[0:2]：表示前两本书。
[
{
"category": "reference",
"author": "Nigel Rees",
"title": "Sayings of the Century",
"price": 8.95
},
{
"category": "fiction",
"author": "Evelyn Waugh",
"title": "Sword of Honour",
"price": 12.99
}
]
$.store.book[-2:].title：表示最后两本书的标题。
[
"Moby Dick",
"The Lord of the Rings"
]
$.store..price：表示所有价格。
[
8.95,
12.99,
8.99,
22.99,
19.95
]
$..book[?(@.price<10)]：表示价格小于 10 的所有书籍。
[
{
"category": "reference",
"author": "Nigel Rees",
"title": "Sayings of the Century",
"price": 8.95
},
{
"category": "fiction",
"author": "Herman Melville",
"title": "Moby Dick",
"isbn": "0-553-21311-3",
"price": 8.99
}
]
以上就是 JsonPath 的语法和示例说明。