通过getClass（）加载文件.getResource（）失败，File（）工作 [英] File loading by getClass().getResource() fails, File() works

问题描述

我正在尝试通过以下代码片段将css文件合并到我的JavaFX应用程序中：

I'm trying to incorporate a css file to my JavaFX appllication, by the following snippet:

public void loadExternalCSS() {
      System.out.println("CLASSPATH: "+System.getProperty("java.class.path"));
      try{
        skinCSS = getClass().getResource("css/default_skin.css").toExternalForm();
      }
      catch(Exception e){
          System.err.println("Exception: " + e);
          e.printStackTrace(System.err);
      }
}

运行时产生的结果：

java.lang.NullPointerException
    at 
robotikosanomologitos.RobotikosAnomologitos.loadExternalCSS(RobotikosAnomologitos.java:529)
    at robotikosanomologitos.RobotikosAnomologitos.start(RobotikosAnomologitos.java:491)
    at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$162(LauncherImpl.java:863)
    at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$175(PlatformImpl.java:326)
    at com.sun.javafx.application.PlatformImpl.lambda$null$173(PlatformImpl.java:295)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.application.PlatformImpl.lambda$runLater$174(PlatformImpl.java:294)
    at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
    at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.java:191)
    at java.lang.Thread.run(Thread.java:745)

奇怪的是，在这个函数上面几行，我有一个从属性文件读取的小函数。

The weird thing is that a few lines above this function, I have a small function that reads from a properties file.

public void readPropertiesFile() {
        Properties props = new Properties();
        InputStream is;
        try {
            File f = new File("properties");
            is = new FileInputStream(f);
        }
        /* etcetera */
}

这是有效的喜欢魅力。 属性文件位于项目目录的根目录， C：\ ~my_projects_folder~ \ RoobotikosAnomologitos

This works like a charm. The properties file is located at the root of the project directory, C:\~my_projects_folder~\RobotikosAnomologitos

在寻找解决方案后，我看到 getClass（）。getResource（）尝试在类路径中查找资源。我试图在每一个版印刷类路径中，我得到：
RobotikosAnomologitos\dist\run125323585\RobotikosAnomologitos.jar 这足以逻辑

After searching around for a solution, I saw that getClass().getResource() attempts to find a resource in the classpath. I tried printing the classpath at every run, and I get: RobotikosAnomologitos\dist\run125323585\RobotikosAnomologitos.jar which is logical enough.

在运行程序的同时查看这个临时文件夹后，我找不到css文件夹或css文件。

After looking inside this temporary folder while running the program, though, I can find no css folder nor css file.

但该文件确实位于我的工作项目目录中，位于 RobotikosAnomologitos \css \default_skin.css 下。由于某种原因，它不会在运行时在类路径中生成它，导致 getResource（）在查找时返回null。

But the file is indeed located in my working project directory, under RobotikosAnomologitos\css\default_skin.css. For some reason it doesn't make it in the classpath at runtime, causing getResource() to return null when looking for it.

关于如何加入它的任何想法？

Any ideas on how to include it?

编辑：我忘记了提到我还在 src 包下放置了 css / default_skin.css ，并显示在Netbeans的包中树（ src / css / default_skin.css ）。

I forgot to mention that I have also placed css/default_skin.css under the src package, and shows up in Netbeans' package tree (src/css/default_skin.css).

以同样的方式，我有一些图形是位于 src / graphics / 下的 getClass（）。getResourceAsStream（）。对于无法找到css文件的原因，这也让我感到困惑。也许它不会在 jar 中编译？

In the same way, I have some graphics that are located under src/graphics/ which get loaded fine by getClass().getResourceAsStream(). Which also bafflesss me as to why the css file can't be found. Maybe it doesn't get compiled in the jar?

推荐答案

如果你为一个类调用 getResource（）并且不预置 / ，该路径被认为是相对于该类的包。

If you call getResource() for a class and do not prepend a /, the path is considered to be relative to the package of the class.

如果你已经将资源正确地添加到类路径中，这应该可行：

If you've properly added the resources to the classpath, this should work:

 skinCSS = getClass().getResource("/css/default_skin.css").toExternalForm();

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