如何在 Java 9 中使用类加载器访问资源 [英] How to access resource using class loader in Java 9

问题描述

我在 Eclipse 中有一个 gradle 项目.这是我的项目结构

I have a gradle project in eclipse. Here is the structure of my project

我在 scr/main/resources/css 中有 css 资源 styleclass.css.首先我尝试使用

I have css resource styleclass.css in scr/main/resources/css. First I tried to access it using

scene.getStylesheets().add("css/styleclass.css"); 

但我收到警告 resource not found. 我也尝试删除 module-info.java 文件.但结果是一样的.

But I was getting warning resource not found. I also tried it by removing module-info.java file. But result is same.

然后我尝试使用

String urlString = ComboBoxStyling.class.getClassLoader().getResource("css/styleclass.css").toExternalForm();

问题是，如果我删除 moduele-info.java 并应用样式表，此行会起作用.但是使用 module-info.java 我得到空指针异常.

Problem is, this line works if I remove moduele-info.java and style sheet applied. But with module-info.java I am getting null pointer exception.

我知道的不多，但至少我知道类加载器在 Java 9 中有变化.那么我如何在 Java 9 中做同样的事情.我的 module-info.java 文件包含以下内容

I don't know much but atleast I know that class loader have changes in Java 9. So how can I do the same in Java 9. My module-info.java file contains the following

module pk.training.basit {
    exports pk.training.basit;
    requires transitive javafx.controls;
}

谢谢&问候

巴斯特·马哈茂德·艾哈迈德

Basit Mahmood Ahmed

推荐答案

来自 ClassLoader.getResource JavaDoc:

From ClassLoader.getResource JavaDoc:

命名模块中的资源遵循 Module.getResourceAsStream 指定的封装规则.此外，除了资源名称以.class"结尾的特殊情况外，此方法只会在无条件打开包时(即使此方法的调用者在同一个包中)才会在命名模块的包中查找资源模块作为资源).

Resources in named modules are subject to the encapsulation rules specified by Module.getResourceAsStream. Additionally, and except for the special case where the resource has a name ending with ".class", this method will only find resources in packages of named modules when the package is opened unconditionally (even if the caller of this method is in the same module as the resource).

因此，要解决您的问题，您应该打开包 css:

So, to fix your issue, you should make the package css open:

module pk.training.basit {
    exports pk.training.basit;
    requires transitive javafx.controls;
    opens css;
}

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