如何在Clojure中加载程序资源 [英] How to load program resources in Clojure

问题描述

如何在Clojure程序中加载程序资源，如图标，字符串，图形元素，脚本等？我使用的项目布局类似于许多Java项目，其中有一个资源目录挂在源目录。一个jar文件是从源代码创建的，并且包含了资源，但我似乎无法像Java一样获得加载的资源。

我试过的第一件事是类似

 （ClassLoader / getSystemResourceresources / myscript.js）
  
 
 
 
但是却找不到资源。
 
 
 
 
 
 
  ... 
（let [cls（.getClass net.mydomain.somenamespace）
 strm（.getResourceAsStream cls name ）] 
 ... 
  
其中name是 / code>要加载的资源，但流是 nil 。
 
 
 
上下文类加载器与
  ... 
 
（let [thr（Thread / currentThread ）
 ldr（.getContextClassLoader thr）
 strem（.getResourceAsStream ldr name）] 
 ... 
  
但 strem 始终为零。
 
 
 
将资源文件放置在程序中的每个目录中。 
 
 
 
我已经查看了的语言来源，加载函数和运行时库，但不是获取。
 
 
 
任何帮助将不胜感激。 b 
 $ b 
  EDIT ：这是一个更具体的例子。在Java中，如果你想将MarkDown转换为HTML，你可以使用 showdown.js 脚本，并写如下：
  package scriptingtest; 
 
 import java.io.InputStreamReader; 
 import javax.script.Invocable; 
 import javax.script.ScriptEngine; 
 import javax.script.ScriptEngineManager; 
 
 public class示例{
 
 private Object converter; 
 
 public String transformMarkDown（String markdownString）{
 ScriptEngineManager manager = new ScriptEngineManager（）; 
 ScriptEngine engine = manager.getEngineByName（js）; 
 try {
 engine.eval（new InputStreamReader（getClass（）。getResourceAsStream（
resources / showdown.js）））; 
 converter = engine.eval（new Showdown.converter（））; 
} catch（Exception e）{
 return无法创建转换器; 
} 
 try {
 return（（Invocable）engine）.invokeMethod（converter，makeHtml，
 markdownString）.toString 
} catch（Exception e）{
 return转换失败; 
} 
} 
 
 public static void main（String [] args）{
 System.out.println（new Example（）。transformMarkDown强调*，**强**））; 
} 
} 
  
当我创建项目时，包装入罐。运行时，程序输出< p> plain，< em> emphasis< / em>，< strong> strong< / strong>< / p>  / p> 
 
 
对Clojure的直译可能非常简单，但是我试图创建 InputStreamReader  
 
 
 
 编辑：自从帖子后添加了markdown标签
解决方案
这是目录结构。
 
 
 
继续使用OP中的脚本引擎示例，Clojure等效项将是：
 （ns com.domain。示例
（：gen-class）
（：import（java.io InputStreamReader））
（：import（javax.script ScriptEngineManager ScriptEngine）））
 
 defn load-resource 
 [name] 
（let [rsc-name（strcom / domain / resources /name）
 thr（Thread / currentThread）
 ldr getContextClassLoader thr）] 
（.getResourceAsStream ldr rsc-name）））
 
（defn markdown-to-html 
 [mkdn] 
 ScriptEngineManager）
引擎（.getEngineByName managerjs）
是（InputStreamReader。 （load-resourceshowdown.js））
 _（.eval engine is）
 cnv-arg（strnew Showdown.converter（）。makeHtml（\mkdn\ ））] 
（.eval engine cnv-arg）））
 
（defn -main 
 [] 
（println（markdown-to-htmlplain ，* emphasis *，** strong **）））
  
注意，资源的路径在Java版本中与 com / domain / scriptingtest / resources 相反， com / domain / resources 在clojure版本中，源文件 example.clj 位于 com / domain 中。在Java版本中，源文件 Example.java 位于 com / domain / scriptingtest 包中。 p> 
 
 
在我的IDE（NetBeans）中设置项目时，Java项目向导会要求提供源代码的封装包。 Clojure插件，enclojure，要求一个命名空间，而不是一个包。我从来没有注意到差别。因此，目录结构中的off-by-one错误预期。
 
How do you load program resources such as icons, strings, graphical elements, scripts, and so on in a Clojure program? I am using a project layout similar to that in many Java projects where there is a "resources" directory hanging off of a "source" directory. A jar file is created from the source and includes the resources, but I can't seem to get the resources loaded as I would in Java.

The first thing I tried was something like
(ClassLoader/getSystemResource "resources/myscript.js")
But could never find the resource.

You can do something similar with
...
  (let [cls (.getClass net.mydomain.somenamespace)
        strm (.getResourceAsStream cls name)        ]
...
where name is the name of the resource to load, but the stream is nil.

You can try using the context class loader with something like
...

(let [thr (Thread/currentThread)
      ldr (.getContextClassLoader thr)
      strem (.getResourceAsStream ldr name)]
...
But strem is always nil.

In frustration, I've tried placing the resource files in just about every directory in the program. They get copied into the jar correctly, but I still can't seem to load them.

I've looked at the language sources for the load function and the run-time library, but am not "getting" it.

Any help would be appreciated.

EDIT: Here's a more concrete example. In Java, if you wanted to convert MarkDown to HTML, you might use the showdown.js script and write something like:
package scriptingtest;

import java.io.InputStreamReader;
import javax.script.Invocable;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;

public class Example {

    private Object converter;

    public String transformMarkDown(String markdownString) {
        ScriptEngineManager manager = new ScriptEngineManager();
        ScriptEngine engine = manager.getEngineByName("js");
        try {
            engine.eval(new InputStreamReader(getClass().getResourceAsStream(
                    "resources/showdown.js")));
            converter = engine.eval("new Showdown.converter()");
        } catch (Exception e) {
            return "Failed to create converter";
        }
        try {
            return ((Invocable) engine).invokeMethod(converter, "makeHtml",
                    markdownString).toString();
        } catch (Exception e) {
            return "Conversion failed";
        }
    }

    public static void main(String[] args) {
        System.out.println(new Example().transformMarkDown("plain, *emphasis*, **strong**"));
    }
}
when I create the project, it all gets compiled and packed into a jar. When run, the program outputs <p>plain, <em>emphasis</em>, <strong>strong</strong></p>

A literal translation to Clojure seems pretty straightforward, but I run into trouble trying to create the InputStreamReader -- I can't seem to write the code needed to find the script file in the jar.

Edit: Added "markdown" tag since the post gives two complete examples of approaches to processing markdown.
解决方案
It's the directory structure.

Continuing with the scripting engine example in the OP, a Clojure equivalent would be:
(ns com.domain.example
  (:gen-class)
  (:import (java.io InputStreamReader))
  (:import (javax.script ScriptEngineManager ScriptEngine)))

(defn load-resource
  [name]
  (let [rsc-name (str "com/domain/resources/" name)
        thr (Thread/currentThread)
        ldr (.getContextClassLoader thr)]
    (.getResourceAsStream ldr rsc-name)))

(defn markdown-to-html
  [mkdn]
  (let [manager (new ScriptEngineManager)
        engine (.getEngineByName manager "js")
        is (InputStreamReader. (load-resource "showdown.js"))
        _ (.eval engine is)
        cnv-arg (str "new Showdown.converter().makeHtml(\"" mkdn "\")")]
    (.eval engine cnv-arg)))

(defn -main
  []
  (println (markdown-to-html "plain, *emphasis*, **strong**")))
Note that the path to the resources is com/domain/resources for this code as opposed to com/domain/scriptingtest/resources in the Java version. In the clojure version, the source file, example.clj is in com/domain. In the Java version, the source file, Example.java is in the com/domain/scriptingtest package.

When setting up a project in my IDE, NetBeans, the Java project wizard asks for an enclosing package for the source. The Clojure plugin, enclojure, asks for a namespace, not a package. I had never noted that difference before. Hence the "off-by-one" error in the directory structure expected.

                        
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