方法说明如下
引用
public URL getResource(String name)
Finds the resource with the given name. A resource is some data (images, audio, text, etc) that can be accessed by class code in a way that is independent of the location of the code.
The name of a resource is a '/'-separated path name that identifies the resource.
这句明确说明，name参数是以‘/’来作为路径分隔符，不是File.separator，如果使用了File.separator，正确的路径也返回null
This method will first search the parent class loader for the resource; if the parent is null the path of the class loader built-in to the virtual machine is searched. That failing, this method will invoke findResource(String) to find the resource.
Parameters:
name - The resource name
Returns:
A URL object for reading the resource, or null if the resource could not be found or the invoker doesn't have adequate privileges to get the resource.
Since: