如何从 Clojure 获取 Java 类的方法? [英] How can I get the methods of a Java class from Clojure?

问题描述

如何从 Clojure 获取 Java 类的方法?

How can I get the methods of a Java class from Clojure?

推荐答案

根据下面 M Smith 的评论，这实现了相同的功能，但提供按方法名称排序且仅返回方法:

Per M Smith's comment below, this accomplishes the same but provides sorting by method name and only returns methods:

(print-table
  (sort-by :name 
    (filter :exception-types (:members (r/reflect "foo")))))

[/EDIT 2]

我最初的回答是指 Clojure 1.2，但随着 Clojure 1.3 的出现，情况发生了变化.现在无需依赖 Clojure 的 contrib 库即可工作:

My original answer refers to Clojure 1.2, but things have changed with Clojure 1.3. This works without any reliance on Clojure's contrib libraries now:

(require '[clojure.reflect :as r])
(use '[clojure.pprint :only [print-table]])

(print-table (:members (r/reflect "foo")))

这提供了一种更加解耦的方法，reflect 函数提供有关传入参数的各种信息(在这种情况下，一个 String "foo") 和 print-table 函数采用任何通用表格数据结构并漂亮地打印出来.

This provides a much more decoupled approach, with the reflect function providing all kinds of information on the argument passed in (in this case, a String "foo") and the print-table function taking any generic tabular data structure and pretty printing it as such.

这最初来自Google 网上论坛上的这个帖子.

[/EDIT]

我会在 clojure.contrib.repl-utils 命名空间中使用 show 函数，它将打印一个对象(或类一个东西).我这样要求:

I'd use the show function in the clojure.contrib.repl-utils namespace, which will print all static and instance members for an object (or class of an object). I require it like so:

(require '[clojure.contrib.repl-utils :as ru])

以下是使用 Joda Time 的示例:

Here's an example using Joda Time:

(import 'org.joda.time.DateTime)
(ru/show DateTime)
(ru/show (DateTime.))

第一个示例演示了如何简单地将类传递给 show，而第二个示例演示了您也可以传递类的实例.

The first example demonstrates how you can simply pass a class to show, while the second demonstrates that you can pass an instance of the class as well.

这当然适用于许多底层 Java 类的 Clojure 项目.这是查看 java.lang.String 实例可用的所有方法的示例:

This of course works for lots of Clojure items that are Java classes underneath. Here's an example of seeing all methods available to an instance of java.lang.String:

(ru/show "foo")

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