问题
Using the snippet below throws me a null pointer exception, but i can't find the reason:
String path = ResourcesLoader.class.getResource("src/i3d/resourcesloader/libraries/lib.txt").toString();
Am i using the getResources wrong? I even tried to enter the full path, like "D:\Workspace...", double backslashes, double forwardslashes but i get the exception of null pointer. The only thing i haven't tried is using java's path separator, but that shouldn't be a problem at this moment as it runs on Windows. What do i miss?
Thanks!
回答1:
getResource searches via the classloader, so typically and simplified in the classpath. The src folder is not in the classpath – it only exists for the build. Depending on your build system (ANT, Maven, IDE internal) a resources folder may be merged into the classpath. You put your resource directly into the source folder which will also work (if the build process copies all non-Java resources to the class output folder or if the source folder is used for the output of the generated classes).
/ is the root for your resources if you use absolute resource locations. It is equivalent to the root within the src folder. /i3d/resourcesloader/libraries/lib.txt would be the correct way to access the resource.
It would be nicer to separate the resources in a separate folder that is merged by the build tool (e.g. in Maven: /src/main/java, /src/main/resources).
回答2:
It seems you are using NetBeans?
Just create a folder called src\resources, get your files inside there, and call this.getClass().getResource("lib.txt");.
Netbeans will pack that properly when building and the resources will be in the main folder inside the jar, so you can get without having to specify their folder.
回答3:
You should only provide relative path from your classloading point (ie without src):
String path = ResourcesLoader.class.getResource("/i3d/resourcesloader/libraries/lib.txt").toString();
来源：https://stackoverflow.com/questions/9466631/java-relative-path