书接上文和上上文：
之前分享了jsonpath的部分API使用，基本已经把基础的内容讲完了，今天分享一下JsonPath API中的函数的使用方法，其实之前讲到的一些json数组的过滤中已经用到了一些函数，大概是因为功能不一样吧，这里将的函数都是处理json数组的，而不是过滤数组的条件。
json数据
在原来的数据基础上增加了部分字段和部分节点。
JSONObject json = JSON.parseObject("{" +
" "store": {" +
" "book": [" +
" {" +
" "category": "reference"," +
" "author": "Nigel Rees"," +
" "title": "Sayings of the Century"," +
" "page": "D"," +
" "pages": ["S","X","G"]," +
" "price": 8.95" +
" }," +
" {" +
" "category": "fiction"," +
" "author": "Evelyn Waugh"," +
" "title": "Sword of Honour"," +
" "page": "A"," +
" "pages": ["A","B"]," +
" "price": 12.99" +
" }," +
" {" +
" "category": "fiction"," +
" "author": "Herman Melville"," +
" "title": "Moby Dick"," +
" "isbn": "0-553-21311-3"," +
" "page": "B"," +
" "pages": ["E","F"]," +
" "price": 8.99" +
" }," +
" {" +
" "category": "fiction"," +
" "author": "J. R. R. Tolkien"," +
" "title": "The Lord of the Rings"," +
" "isbn": "0-395-19395-8"," +
" "page": "C"," +
" "pages": ["C","D"]," +
" "price": 22.99" +
" }" +
" ]," +
" "bicycle": {" +
" "color": "red"," +
" "price": 19.95" +
" }" +
" }," +
" "expensive": 10," +
" "ss": [32,32,4,23]" +
"}");
获取数组最小值
jsonpath：$.ss.min()
代码：
Object read = JsonPath.read(json, "$.ss.min()");
output(read);
等效写法继续省略……
控制台输出：
INFO-> 当前用户：fv，IP：10.60.192.21，工作目录：/Users/fv/Documents/workspace/fun/,系统编码格式:UTF-8,系统Mac OS X版本:10.15.6
INFO-> 4.0
Process finished with exit code 0
- 这里需要注意，该方法返回值是一个
double的数值，测试中用的int整型，但是结果返回的是4.0。
获取数组的最大值
jsonpath：$.ss.max()
代码：
Object read = JsonPath.read(json, "$.ss.max()");
output(read);
等效写法继续省略……
控制台输出：
INFO-> 当前用户：fv，IP：10.60.192.21，工作目录：/Users/fv/Documents/workspace/fun/,系统编码格式:UTF-8,系统Mac OS X版本:10.15.6
INFO-> 32.0
Process finished with exit code 0
- 同样的，
max函数返回的也是double浮点型数据。
获取数组的平均值
jsonpath：$.ss.avg()
代码：
Object read = JsonPath.read(json, "$.ss.avg()");
output(read);
等效写法继续省略……
控制台输出：
INFO-> 当前用户：fv，IP：10.60.192.21，工作目录：/Users/fv/Documents/workspace/fun/,系统编码格式:UTF-8,系统Mac OS X版本:10.15.6
INFO-> 22.75
Process finished with exit code 0
- 同样的，
max函数返回的也是double浮点型数据。
获取数组的标准差
jsonpath：$.ss.stddev()
代码：
Object read = JsonPath.read(json, "$.ss.stddev()");
output(read);
等效写法继续省略……
控制台输出：
INFO-> 当前用户：fv，IP：10.60.192.21，工作目录：/Users/fv/Documents/workspace/fun/,系统编码格式:UTF-8,系统Mac OS X版本:10.15.6
INFO-> 11.431863365173676
Process finished with exit code 0
- 同样的，
stddev函数返回的也是double浮点型数据。
获取数组的长度
- 对于
json数组适用。
jsonpath：$.ss.length()
jsonpath：$.store.book.length()
代码：
Object read = JsonPath.read(json, "$.ss.length()");
output(read);
Object read = JsonPath.read(json, "$.store.book.length()");
output(read);
等效写法继续省略……
控制台输出：
INFO-> 当前用户：fv，IP：10.60.192.21，工作目录：/Users/fv/Documents/workspace/fun/,系统编码格式:UTF-8,系统Mac OS X版本:10.15.6
INFO-> 4
Process finished with exit code 0
求数组的和
jsonpath：$.ss.sum()
代码：
Object read = JsonPath.read(json, "$.ss.sum()");
output(read);
等效写法继续省略……
控制台输出：
INFO-> 当前用户：fv，IP：10.60.192.21，工作目录：/Users/fv/Documents/workspace/fun/,系统编码格式:UTF-8,系统Mac OS X版本:10.15.6
INFO-> 91.0
Process finished with exit code 0
- 同样的，
sun函数返回的也是double浮点型数据。
自此，JsonPath API系列已经更完了，我在积极准备JsonPath util的内容，使用Groovy的Groovy重载操作符（终极版）功能，敬请期待。
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