// Parse a single line from the given configuration file, adding the name
// on the line to the names list.
//
private int parseLine(Class<?> service, URL u, BufferedReader r, int lc, List<String> names)
throws IOException, ServiceConfigurationError {
String ln = r.readLine();
if (ln == null) {
return -1;
}
int ci = ln.indexOf('#');
if (ci >= 0) ln = ln.substring(0, ci);
ln = ln.trim();
int n = ln.length();
if (n != 0) {
if ((ln.indexOf(' ') >= 0) || (ln.indexOf('\t') >= 0))
fail(service, u, lc, "Illegal configuration-file syntax");
int cp = ln.codePointAt(0);
if (!Character.isJavaIdentifierStart(cp))
fail(service, u, lc, "Illegal provider-class name: " + ln);
for (int i = Character.charCount(cp); i < n; i += Character.charCount(cp)) {
cp = ln.codePointAt(i);
if (!Character.isJavaIdentifierPart(cp) && (cp != '.'))
fail(service, u, lc, "Illegal provider-class name: " + ln);
}
if (!providers.containsKey(ln) && !names.contains(ln)) names.add(ln);
}
return lc + 1;
}
// Parse the content of the given URL as a provider-configuration file.
//
// @param service
// The service type for which providers are being sought;
// used to construct error detail strings
//
// @param u
// The URL naming the configuration file to be parsed
//
// @return A (possibly empty) iterator that will yield the provider-class
// names in the given configuration file that are not yet members
// of the returned set
//
// @throws ServiceConfigurationError
// If an I/O error occurs while reading from the given URL, or
// if a configuration-file format error is detected
//
private Iterator<String> parse(Class<?> service, URL u) throws ServiceConfigurationError {
InputStream in = null;
ArrayList<String> names = new ArrayList<>();
try {
// The problem is that by default, streams opened with
// u.openInputStream use a cached reference to a JarFile, which
// is separate from the reference used by URLClassLoader, and
// which is not closed by URLClassLoader.close().
// The workaround is to disable caching for this specific jar file,
// so that the reference to the jar file can be closed when the
// file has been read.
// Original code:
// in = u.openStream();
// Workaround ...
URLConnection uc = u.openConnection();
uc.setUseCaches(false);
in = uc.getInputStream();
// ... end of workaround.
try (BufferedReader r = new BufferedReader(new InputStreamReader(in, "utf-8"))) {
int lc = 1;
while ((lc = parseLine(service, u, r, lc, names)) >= 0) ;
}
} catch (IOException x) {
fail(service, "Error reading configuration file", x);
} finally {
try {
if (in != null) in.close();
} catch (IOException y) {
fail(service, "Error closing configuration file", y);
}
}
return names.iterator();
}
private static void fail(Class<?> service, URL u, int line, String msg)
throws ServiceConfigurationError {
fail(service, u + ":" + line + ": " + msg);
}