我如何调试资源路径加载或一般的 ClassLoader？

Question

我已经阅读了一些在加载资源时遇到问题的人提出的问题。我已按照他们的说明进行操作（尽管这些说明实际上有所不同，这意味着两者都不正确 - 我都试过了）。

我创建了 enum 以便在需要时为我加载资源。它很长，但我会分享它，以防有人从 google 来到这里并可以利用它：

package cz.autoclient.GUI;
/**
 * Enum of resources used for GUI. These resources are packed in .jar and are for internal use.
 * Provides lazy-loaded Image and ImageIcon for comfort.
 * @author Jakub
 */
public enum ImageResources {
  ICON("IconHighRes.png");
  //So according to [this guy]( I
  //  should enter classpath beginning with slash to make sure it's absolute path from
  //  the root of my .jar
  public static final String basepath = "/cz/autoclient/resources/";
  //Cache everything to have less letters to write
  public static final ClassLoader loader = ImageResources.class.getClassLoader();
  public static final Class leclass = ImageResources.class;
  //String is immutable so it's ok to make it a public constant
  public final String path;
  //These will fill up on demand when needed
  private ImageIcon icon;
  private Image image = null;
  //If image has failed, we'll not try to load it again and will return null straight away
  private boolean image_failed = false;
  //Constructor concatenates the individual path with the global path
  ImageResources(String path) {
    this.path = basepath+path;
  }

  /** Loads, or just retrieves from cache, the image.
   *  @return Image (not necesarily a BufferedImage) or null on failure
  */
  public Image getImage() {
    //Lazy load...
    if(image==null) {
      //Since the .jar is constant (it's packed) we can
      //Remember the image is unavailable
      if(image_failed)
        return null;
      //Use whatever is stored in Icon if we have it
      if(icon!=null) {
        image = icon.getImage();
      }
      //Load from .jar
      else {
        try {
          image = ImageIO.read(leclass.getResourceAsStream("/images/grass.png"));
        }
        //While only IOException is reported it also can throw InvalidArgumentException
        // when read() argument is null
        catch(Exception e) {
          image_failed = true;
        }
      }
    }
    return image;
  }
}

^{Full version on GitHub. 可能会发生变化。}

由于此代码不起作用（由于无效的基本路径）我想知道找到为什么资源没有加载和的一般方法ClassLoader 在哪里看.

例如，当我从文件系统加载普通文件时遇到问题，我可以这样做：

File relativePath = new File("../my_test_image.png");
System.out.println(relativePath.getAbsolutePath());

而且我可以立即看到 Java 在看哪里以及我应该更改什么。如果我和其他人知道一个简单的方法来使用资源，那么所有这些问题都不需要问：

Getting a BufferedImage as a resource so it will work in JAR file
loading BufferedImage with ClassLoader.getResource()
java getResource() not working
Resource loading in Java not working as it should
How to correctly get image from 'Resources' folder in NetBeans

那么有没有办法打印我的资源路径转换成什么？

我尝试了什么：

((URLClassLoader) (Thread.currentThread().getContextClassLoader())).getURLs();
System.out.println(" Current path: \""+loader.getResource("ImageResources.class")+"\")"); - 打印 Current path: "null"

Answer 1

看来你总能通过这条语句得到当前路径：

System.out.println("  Path: \""+loader.getResource(".")+"\"");

对我来说，这给出了：

  Path: "file:/C:/... path to project .../PROJECT_NAME/target/test-classes/"

这是测试的路径 class 运行测试，而不是实际的 class loader 创建它的路径。我不认为这是一个错误。

我如何调试资源路径加载或一般的 ClassLoader？

How can I debug resources path loading or the ClassLoader in general?

java

netbeans

embedded-resource