Java resource as file

Question

Is there a way in Java to construct a File instance on a resource retrieved from a jar through the classloader   My application uses some files from the jar  default  or from a filesystem directory specified at runtime  user input   I m looking for a consistent way of a  loading these files as a stream b  listing the files in the user-defined directory or the directory in the jar respectively  Edit  Apparently  the ideal approach would be to stay away from java io File altogether  Is there a way to load a directory from the classpath and list its contents  files entities contained in it

User · Answer

Try this   ClassLoader getResourceAsStream   some pkg resource properties      There are more methods available  e g  see here   http   www javaworld com javaworld javaqa 2003-08 01-qa-0808-property html

User · Answer

I had the same problem and was able to use the following      Load the directory as a resource URL dir url   ClassLoader getSystemResource dir path      Turn the resource into a File object File dir   new File dir url toURI        List the directory String files   dir list

User · Answer

This is one option  http   www uofr net  greg java get-resource-listing html

User · Answer

A reliable way to construct a File instance on a resource retrieved from a jar is it to copy the resource as a stream into a temporary File  the temp file will be deleted when the JVM exits    public static File getResourceAsFile String resourcePath        try           InputStream in   ClassLoader getSystemClassLoader   getResourceAsStream resourcePath           if  in    null                return null                     File tempFile   File createTempFile String valueOf in hashCode       tmp            tempFile deleteOnExit             try  FileOutputStream out   new FileOutputStream tempFile                   copy stream             byte   buffer   new byte 1024               int bytesRead              while   bytesRead   in read buffer      -1                    out write buffer  0  bytesRead                                   return tempFile        catch  IOException e            e printStackTrace            return null

User · Answer

Here is a bit of code from one of my applications    Let me know if it suits your needs   You can use this if you know the file you want to use    URL defaultImage   ClassA class getResource   packageA subPackage image-name png    File imageFile   new File defaultImage toURI       Hope that helps

User · Answer

ClassLoader getResourceAsStream and Class getResourceAsStream are definitely the way to go for loading the resource data  However  I don t believe there s any way of  listing  the contents of an element of the classpath   In some cases this may be simply impossible - for instance  a ClassLoader could generate data on the fly  based on what resource name it s asked for  If you look at the ClassLoader API  which is basically what the classpath mechanism works through  you ll see there isn t anything to do what you want   If you know you ve actually got a jar file  you could load that with ZipInputStream to find out what s available  It will mean you ll have different code for directories and jar files though   One alternative  if the files are created separately first  is to include a sort of manifest file containing the list of available resources  Bundle that in the jar file or include it in the file system as a file  and load it before offering the user a choice of resources

[java] Java resource as file

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