如何从Java调用Clojure代码 [英] How to Call Clojure Code From Java
问题描述
我的教授允许我练习Clojure和Java！我肯定是在利用这个机会，并希望让我的第一个Java任务调用一些Clojure代码。在我进入实际作业之前，我想创建一个简单，有效的例子。我需要你的帮助。
My professor allowed me to practice both Clojure and Java! I'm definitely using the opportunity and want to have my first Java assignment call some Clojure code. Before I go to the actual assignment, I want to create a simple, working example. I need your help.
我已经阅读了一些关于Java / Clojure互操作性的链接。 这，以及这个。
I have read a few links on Java/Clojure interoperability. This, and This.
我将使用第一个链接来演示我的内容到目前为止已经完成了：
I will use the first link to demonstrate what I have done so far:
1）我创建了一个Clojure项目，从站点中转储.cli文件并使用Eclipse中的导出函数将其导出为a .jar到我的Documents目录中的一个文件夹。
1) I have created a Clojure Project, dumped the .cli file from the site in it and use the export function in Eclipse to export it as a .jar to a folder in my Documents directory.
2）我创建了第二个Java项目，将java文件转储到其中并添加了clojure.jar作为参考图书馆。
2) I have created a second Java Project, dumped the java file into it and added the clojure.jar as a referenced library.
Clojure ns：
Clojure ns:
(ns com.tiny
(:gen-class
:name com.tiny
:methods [#^{:static true} [binomial [int int] double]]))
Java导入：
import com.tiny;
Java文件无法识别 com.tiny 。我不知道为什么。这些网站提到了一些类路径。所以我在eclipse中找到了类路径编辑器，并将带有.jar的必需文件夹添加到路径列表中。这也行不通。
The Java file does not recognize com.tiny. I don't know why. The sites mentioned something about a class-path. So I found the classpath editor in eclipse and added the required folder with the .jar to the list of paths. This also did not work.
我不知道我做错了什么。我引用了jar，将它添加到类路径中，并在第一个链接中完成了代码的完整复制粘贴（除了包名称）。
I don't know what I'm doing wrong. I have referenced the jar, added it to the classpath, and did a complete copy-paste of the code in the first link (besides the package name).
Java代码：
import com.tiny;
public class Main {
public static void main(String[] args) {
System.out.println("(binomial 5 3): " + tiny.binomial(5, 3));
System.out.println("(binomial 10042, 111): " + tiny.binomial(10042, 111));
}
}
Clojure代码：
Clojure code:
(ns com.tiny
(:gen-class
:name com.tiny
:methods [#^{:static true} [binomial [int int] double]]))
(defn binomial
"Calculate the binomial coefficient."
[n k]
(let [a (inc n)]
(loop [b 1
c 1]
(if (> b k)
c
(recur (inc b) (* (/ (- a b) b) c))))))
(defn -binomial
"A Java-callable wrapper around the 'binomial' function."
[n k]
(binomial n k))
(defn -main []
(println (str "(binomial 5 3): " (binomial 5 3)))
(println (str "(binomial 10042 111): " (binomial 10042 111)))
)
推荐答案
为了成功运行您的示例，我执行了以下操作：
To successfully get your example to run, I did the following:
1）在Eclipse中创建了一个Clojure项目
2）在src / com / tiny.clj
3）Expo中添加了文件tiny.clj将该项目作为.jar文件（例如：tiny.jar）
1) Created a Clojure project in Eclipse 2) Added the file tiny.clj in src/com/tiny.clj 3) Exported that project as a .jar file (e.g.: tiny.jar)
4）使用一个Java文件创建Java项目 - Main.java
5）将clojure.jar和tiny.jar添加到Java项目的类路径中。 （右键单击 - >配置构建路径 - >库选项卡 - >添加外部JAR）
4) Created the Java project as you describe, with one Java file - Main.java 5) Add clojure.jar and tiny.jar to the Java project's classpath. (Right-click -> Configure Build Path -> Libraries Tab -> Add External JARs)
当我最初尝试这个时，我没有放下tiny.clj文件在com /目录中（我直接在src /下），当我试图运行Main类时，我得到一个RuntimeException，表示找不到文件tiny.clj和tiny__init.class。将tiny.clj文件移动到com /子目录，为我和主要雨成功解决了问题。
When I initially tried this, I didn't put the tiny.clj file in the com/ directory (I had it directly under src/), and I got a RuntimeException when I tried to run the Main class that said the file tiny.clj and tiny__init.class couldn't be found. Moving the tiny.clj file to the com/ subdirectory fixed the issue for me and Main rain successfully.
这篇关于如何从Java调用Clojure代码的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
