Java

JSONPath 笔记

继续 json 系列：

JSONPath 虽然简单，但偶尔用起来还要去求助搜索引擎，这里做下常用笔记。

在线验证： http://jsonpath.com/
Java包： https://github.com/json-path/JsonPath （GitHub上Star最多的）

操作符

符号 描述
$ 查询的根节点对象，用于表示一个json数据，可以是数组或对象
@ 过滤器断言（filter predicate）处理的当前节点对象，类似于java中的this字段
* 通配符，可以表示一个名字或数字
.. 可以理解为递归搜索，Deep scan. Available anywhere a name is required.
. 表示一个子节点
[‘’ (, ‘’)] 表示一个或多个子节点
[ (, )] 表示一个或多个数组下标
[start:end] 数组片段，区间为[start,end),不包含end
[?()] 过滤器表达式，表达式结果必须是boolean

函数

名称 描述 输出
min() 获取数值类型数组的最小值 Double
max() 获取数值类型数组的最大值 Double
avg() 获取数值类型数组的平均值 Double
stddev() 获取数值类型数组的标准差 Double
length() 获取数值类型数组的长度 Integer

过滤器

操作符 描述
== 等于符号，但数字1不等于字符1(note that 1 is not equal to ‘1’)
!= 不等于符号
< 小于符号
<= 小于等于符号
> 大于符号
>= 大于等于符号
=~ 判断是否符合正则表达式，例如[?(@.name =~ /foo.*?/i)]
in 所属符号，例如[?(@.size in [‘S’, ‘M’])]
nin 排除符号
size size of left (array or string) should match right
empty 判空符号

示例

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{
    "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
        }
    },
    "expensive": 10
}
JsonPath (click link to try) Result
$.store.book[*].author The authors of all books
$..author All authors
$.store.* All things, both books and bicycles
$.store..price The price of everything
$..book[2] The third book
$..book[-2] The second to last book
$..book[0,1] The first two books
$..book[:2] All books from index 0 (inclusive) until index 2 (exclusive)
$..book[1:2] All books from index 1 (inclusive) until index 2 (exclusive)
$..book[-2:] Last two books
$..book[2:] Book number two from tail
$..book[?(@.isbn)] All books with an ISBN number
$.store.book[?(@.price < 10)] All books in store cheaper than 10
$..book[?(@.price <= $[‘expensive’])] All books in store that are not “expensive”
$..book[?(@.author =~ /.*REES/i)] All books matching regex (ignore case)
$..* Give me every thing
$..book.length() The number of books