打开打包在 JAR 中的 PDF 文件

Question

I am trying to open a PDF file that is packaged into the jar file during runtime. The basic idea is that the user clicks the help option and then it displays a help file that is a PDF. Right now I have this in LineFit.class in the linefit package to try and open the help PDF:

try {
  File test = new File(LineFit.class.getClass().getResource("/linefit/helpTest.pdf").toURI());
  try {
      Desktop.getDesktop().open(test);
  } catch (IOException e1) {
      // TODO Auto-generated catch block
      e1.printStackTrace();
  } 
} catch (URISyntaxException e2) {
  // TODO Auto-generated catch block
  e2.printStackTrace();
}

It works in eclipse when I run it but if I try to export it to a runnable JAR file it does not open the PDF file and when I look into the JAR, the PDF is in the same folder as when it was in eclipse.

Answer 1

new File(URI) only works for file: URIs. When a classloader finds a resource in a jar, it returns a jar URI, for example jar:file:/C:/Program%20Files/test.jar!/foo/bar .

Fundamentally, the File class is for files on the filesystem. You can't use it to represent a file within a JAR or another archive. You're going to have to copy the file out of the jar and into a regular file, then create a File referencing this new file. To read the file from the jar, you could use JarURLConnection.getInputStream with the URL you have, or you could call ClassLoader.getResourceAsStream .

Answer 2

Try this:

Make sure the path of pdf file is relative path when you use MethodHandles.lookup().lookupClass().getClassLoader()

InputStream is = MethodHandles.lookup().lookupClass().getClassLoader().getResourceAsStream("doc/example.pdf");
BufferedReader br = new BufferedReader(new InputStreamReader(is));
while ((thisLine = br.readLine()) != null) {
            System.out.println(thisLine);
         }