I am looking for a way to get a list of all resource names from a given classpath directory, something like a method List<String> getResourceNames (String directoryName)
.
For example, given a classpath directory x/y/z
containing files a.html
, b.html
, c.html
and a subdirectory d
, getResourceNames("x/y/z")
should return a List<String>
containing the following strings:['a.html', 'b.html', 'c.html', 'd']
.
It should work both for resources in filesystem and jars.
I know that I can write a quick snippet with File
s, JarFile
s and URL
s, but I do not want to reinvent the wheel. My question is, given existing publicly available libraries, what is the quickest way to implement getResourceNames
? Spring and Apache Commons stacks are both feasible.
Implement your own scanner. For example:
private List<String> getResourceFiles(String path) throws IOException {
List<String> filenames = new ArrayList<>();
try (
InputStream in = getResourceAsStream(path);
BufferedReader br = new BufferedReader(new InputStreamReader(in)))
String resource;
while ((resource = br.readLine()) != null) {
filenames.add(resource);
}
}
return filenames;
}
private InputStream getResourceAsStream(String resource) {
final InputStream in
= getContextClassLoader().getResourceAsStream(resource);
return in == null ? getClass().getResourceAsStream(resource) : in;
}
private ClassLoader getContextClassLoader() {
return Thread.currentThread().getContextClassLoader();
}
Use PathMatchingResourcePatternResolver
from Spring Framework.
The other techniques might be slow at runtime for huge CLASSPATH values. A faster solution is to use ronmamo's Reflections API, which precompiles the search at compile time.