/**
* Create a new plugin manager.
*
* @param pluginType Core type for a plugin.
* @param pluginCategory Provides a category name to the plugin. Must not be null.
* @param pluginSuffix Provides a suffix that will be trimmed off when converting to a plugin
* name. Can be null.
* @param classpath Custom class path to search for classes.
*/
public PluginManager(
Class pluginType, String pluginCategory, String pluginSuffix, List<URL> classpath) {
this.pluginCategory = pluginCategory;
this.pluginSuffix = pluginSuffix;
this.plugins = new ArrayList<Class<? extends PluginType>>();
this.interfaces = new ArrayList<Class<? extends PluginType>>();
Reflections reflections;
if (classpath == null) {
reflections = defaultReflections;
} else {
addClasspath(classpath);
reflections =
new Reflections(
new ConfigurationBuilder().setUrls(classpath).setScanners(new SubTypesScanner()));
}
// Load all classes types filtering them by concrete.
@SuppressWarnings("unchecked")
Set<Class<? extends PluginType>> allTypes = reflections.getSubTypesOf(pluginType);
for (Class<? extends PluginType> type : allTypes) {
// The plugin manager does not support anonymous classes; to be a plugin, a class must have a
// name.
if (JVMUtils.isAnonymous(type)) continue;
if (JVMUtils.isConcrete(type)) plugins.add(type);
else interfaces.add(type);
}
pluginsByName = new TreeMap<String, Class<? extends PluginType>>();
for (Class<? extends PluginType> pluginClass : plugins) {
String pluginName = getName(pluginClass);
pluginsByName.put(pluginName, pluginClass);
}
// sort the plugins so the order of elements is deterministic
sortPlugins(plugins);
sortPlugins(interfaces);
}
/**
* Adds the URL to the system class loader classpath using reflection. HACK: Uses reflection to
* modify the class path, and assumes loader is a URLClassLoader.
*
* @param urls URLs to add to the system class loader classpath.
*/
private static void addClasspath(List<URL> urls) {
Set<URL> existing = JVMUtils.getClasspathURLs();
for (URL url : urls) {
if (existing.contains(url)) continue;
try {
Method method = URLClassLoader.class.getDeclaredMethod("addURL", URL.class);
if (!method.isAccessible()) method.setAccessible(true);
method.invoke(ClassLoader.getSystemClassLoader(), url);
} catch (Exception e) {
throw new ReviewedStingException("Error adding url to the current classloader.", e);
}
}
}
static {
// turn off logging in the reflections library - they talk too much
Reflections.log = null;
Set<URL> classPathUrls = new LinkedHashSet<URL>();
URL cwd;
try {
cwd = new File(".").getAbsoluteFile().toURI().toURL();
} catch (MalformedURLException e) {
throw new RuntimeException(e);
}
// NOTE: Reflections also scans directories for classes.
// Meanwhile some of the jar MANIFEST.MF Bundle-ClassPath properties contain "."
// Do NOT let reflections scan the CWD where it often picks up test classes when
// they weren't explicitly in the classpath, for example the UninstantiableWalker
for (URL url : JVMUtils.getClasspathURLs()) if (!url.equals(cwd)) classPathUrls.add(url);
defaultReflections =
new Reflections(
new ConfigurationBuilder().setUrls(classPathUrls).setScanners(new SubTypesScanner()));
}