关闭使用Java JsonPath

Question

我正在尝试在Clojure中使用https://github.com/json-path/JsonPath

从自述文件看，它看起来很简单，特别是因为它使用了静态函数。所以我从自述中复制了这个例子：

(import '[com.jayway.jsonpath JsonPath Criteria Filter])


(JsonPath/parse "{\"a\":\"1\"}") ;; returns a com.jayway.jsonpath.internal.JsonContext

(JsonPath/read (JsonPath/parse "{\"a\":\"1\"}") "$.a")
;; (.read (JsonPath/parse "{\"a\":\"1\"}") "$.a")
;; Exception ->
;; 1. Caused by java.lang.IllegalArgumentException
;; No matching method: read
;; I tried variations of the above line
;; for some reason this seems to want to take `this` as first parameter - I cannot
;; figure out why, and cannot seem to be able to pass a valid value

如何从Clojure调用这个Java静态函数？它为什么要作为this

依赖关系：[com.jayway.jsonpath/json-path "2.4.0"]

Answer 1

问题是在Predicate上使用read的varargs。在JVM级别上，必须将那些args作为数组传递。使用Java，编译器将处理这个问题。

例如，这项工作：

user=> (import '[com.jayway.jsonpath JsonPath Criteria Filter Predicate])
#<Class@5a114a96 com.jayway.jsonpath.Predicate>
user=> (JsonPath/read "{\"a\":\"1\"}" "$.a" (into-array Predicate []))
"1"