*/
package org.opendaylight.yangtools.util;
-import static com.google.common.base.Preconditions.checkNotNull;
+import static java.util.Objects.requireNonNull;
+
+import com.google.common.annotations.Beta;
import com.google.common.base.Joiner;
-import com.google.common.base.Preconditions;
import com.google.common.base.Splitter;
-import com.google.common.base.Supplier;
-import java.lang.reflect.Constructor;
-import java.lang.reflect.InvocationTargetException;
+import com.google.common.collect.Iterables;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.List;
+import java.util.Optional;
import java.util.concurrent.Callable;
+import java.util.function.Function;
+import java.util.function.Supplier;
+import org.eclipse.jdt.annotation.NonNull;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
+/**
+ * Utility methods for working with ClassLoaders and classes.
+ */
public final class ClassLoaderUtils {
private static final Logger LOG = LoggerFactory.getLogger(ClassLoaderUtils.class);
+ private static final Joiner DOT_JOINER = Joiner.on(".");
private static final Splitter DOT_SPLITTER = Splitter.on('.');
private ClassLoaderUtils() {
- throw new UnsupportedOperationException("Utility class");
+ // Hidden on purpose
}
/**
- *
- * Runs {@link Supplier} with provided {@link ClassLoader}.
- *
- * Invokes supplies function and makes sure that original {@link ClassLoader}
- * is context {@link ClassLoader} after execution.
+ * Immediately call {@link Function#apply(Object)} with provided {@link ClassLoader}. This method safely switches
+ * the thread's Thread Context Class Loader to the specified class loader for the duration of execution of that
+ * method.
*
* @param cls {@link ClassLoader} to be used.
- * @param function Function to be executed.
- * @return Result of supplier invocation.
- *
+ * @param function Function to be applied.
+ * @param input Function input
+ * @throws NullPointerException if class loader or function is null
*/
- public static <V> V withClassLoader(final ClassLoader cls, final Supplier<V> function) {
- checkNotNull(cls, "Classloader should not be null");
- checkNotNull(function, "Function should not be null");
-
- final ClassLoader oldCls = Thread.currentThread().getContextClassLoader();
+ @Beta
+ public static <T, R> R applyWithClassLoader(final @NonNull ClassLoader cls, final @NonNull Function<T, R> function,
+ final T input) {
+ final Thread currentThread = Thread.currentThread();
+ final ClassLoader oldCls = currentThread.getContextClassLoader();
+ currentThread.setContextClassLoader(requireNonNull(cls));
try {
- Thread.currentThread().setContextClassLoader(cls);
- return function.get();
+ return requireNonNull(function).apply(input);
} finally {
- Thread.currentThread().setContextClassLoader(oldCls);
+ currentThread.setContextClassLoader(oldCls);
}
}
/**
- *
- * Runs {@link Callable} with provided {@link ClassLoader}.
- *
- * Invokes supplies function and makes sure that original {@link ClassLoader}
- * is context {@link ClassLoader} after execution.
+ * Immediately call {@link Callable#call()} with provided {@link ClassLoader}. This method safely switches
+ * the thread's Thread Context Class Loader to the specified class loader for the duration of execution of that
+ * method.
*
* @param cls {@link ClassLoader} to be used.
- * @param function Function to be executed.
+ * @param callable Function to be executed.
* @return Result of callable invocation.
- *
+ * @throws NullPointerException if class loader or callable is null
*/
- public static <V> V withClassLoader(final ClassLoader cls, final Callable<V> function) throws Exception {
- checkNotNull(cls, "Classloader should not be null");
- checkNotNull(function, "Function should not be null");
-
- final ClassLoader oldCls = Thread.currentThread().getContextClassLoader();
+ @Beta
+ public static <V> V callWithClassLoader(final @NonNull ClassLoader cls, final @NonNull Callable<V> callable)
+ throws Exception {
+ final Thread currentThread = Thread.currentThread();
+ final ClassLoader oldCls = currentThread.getContextClassLoader();
+ currentThread.setContextClassLoader(requireNonNull(cls));
try {
- Thread.currentThread().setContextClassLoader(cls);
- return function.call();
+ return requireNonNull(callable).call();
} finally {
- Thread.currentThread().setContextClassLoader(oldCls);
+ currentThread.setContextClassLoader(oldCls);
}
}
- public static Object construct(final Constructor<?> constructor, final List<Object> objects)
- throws InstantiationException, IllegalAccessException, IllegalArgumentException, InvocationTargetException {
- final Object[] initargs = objects.toArray();
- return constructor.newInstance(initargs);
+ /**
+ * Immediately call {@link Supplier#get()} with provided {@link ClassLoader}. This method safely switches
+ * the thread's Thread Context Class Loader to the specified class loader for the duration of execution of that
+ * method.
+ *
+ * @param cls {@link ClassLoader} to be used.
+ * @param supplier Function to be executed.
+ * @return Result of supplier invocation.
+ * @throws NullPointerException if class loader or supplier is null
+ */
+ @Beta
+ public static <V> V getWithClassLoader(final @NonNull ClassLoader cls, final @NonNull Supplier<V> supplier) {
+ final Thread currentThread = Thread.currentThread();
+ final ClassLoader oldCls = currentThread.getContextClassLoader();
+ currentThread.setContextClassLoader(requireNonNull(cls));
+ try {
+ return requireNonNull(supplier).get();
+ } finally {
+ currentThread.setContextClassLoader(oldCls);
+ }
}
/**
+ * Immediately call {@link Runnable#run()} with provided {@link ClassLoader}. This method safely switches
+ * the thread's Thread Context Class Loader to the specified class loader for the duration of execution of that
+ * method.
*
+ * @param cls {@link ClassLoader} to be used.
+ * @param runnable Function to be executed.
+ * @throws NullPointerException if class loader or runnable is null
+ */
+ @Beta
+ public static void runWithClassLoader(final @NonNull ClassLoader cls, final @NonNull Runnable runnable) {
+ final Thread currentThread = Thread.currentThread();
+ final ClassLoader oldCls = currentThread.getContextClassLoader();
+ currentThread.setContextClassLoader(requireNonNull(cls));
+ try {
+ requireNonNull(runnable).run();
+ } finally {
+ currentThread.setContextClassLoader(oldCls);
+ }
+ }
+
+ /**
* Loads class using this supplied classloader.
*
- *
- * @param cls
* @param name String name of class.
- * @return
- * @throws ClassNotFoundException
*/
public static Class<?> loadClass(final ClassLoader cls, final String name) throws ClassNotFoundException {
if ("byte[]".equals(name)) {
if (isInnerClass(components)) {
final int length = components.size() - 1;
- final String outerName = Joiner.on(".").join(components.subList(0, length));
+ final String outerName = DOT_JOINER.join(Iterables.limit(components, length));
final String innerName = outerName + "$" + components.get(length);
return cls.loadClass(innerName);
- } else {
- throw e;
}
+
+ throw e;
}
}
}
public static Class<?> loadClassWithTCCL(final String name) throws ClassNotFoundException {
- return loadClass(Thread.currentThread().getContextClassLoader(), name);
+ final Thread thread = Thread.currentThread();
+ final ClassLoader tccl = thread.getContextClassLoader();
+ if (tccl == null) {
+ throw new ClassNotFoundException("Thread " + thread + " does not have a Context Class Loader, cannot load "
+ + name);
+ }
+ return loadClass(tccl, name);
}
- public static Class<?> tryToLoadClassWithTCCL(final String fullyQualifiedName) {
+ public static Optional<Class<?>> tryToLoadClassWithTCCL(final String fullyQualifiedClassName) {
+ final Thread thread = Thread.currentThread();
+ final ClassLoader tccl = thread.getContextClassLoader();
+ if (tccl == null) {
+ LOG.debug("Thread {} does not have a Context Class Loader, not loading class {}", thread,
+ fullyQualifiedClassName);
+ return Optional.empty();
+ }
+
try {
- return loadClassWithTCCL(fullyQualifiedName);
+ return Optional.of(loadClass(tccl, fullyQualifiedClassName));
} catch (final ClassNotFoundException e) {
- LOG.debug("Failed to load class {}", fullyQualifiedName, e);
- return null;
+ LOG.debug("Failed to load class {}", fullyQualifiedClassName, e);
+ return Optional.empty();
}
}
- public static <S,G,P> Class<P> findFirstGenericArgument(final Class<S> scannedClass, final Class<G> genericType) {
- return withClassLoader(scannedClass.getClassLoader(), ClassLoaderUtils.<S,G,P>findFirstGenericArgumentTask(scannedClass, genericType));
- }
-
- private static <S,G,P> Supplier<Class<P>> findFirstGenericArgumentTask(final Class<S> scannedClass, final Class<G> genericType) {
- return new Supplier<Class<P>>() {
- @Override
- @SuppressWarnings("unchecked")
- public Class<P> get() {
- final ParameterizedType augmentationGeneric = findParameterizedType(scannedClass, genericType);
- if (augmentationGeneric != null) {
- return (Class<P>) augmentationGeneric.getActualTypeArguments()[0];
- }
- return null;
- }
- };
+ @SuppressWarnings("unchecked")
+ public static <S, G, P> Optional<Class<P>> findFirstGenericArgument(final Class<S> scannedClass,
+ final Class<G> genericType) {
+ return getWithClassLoader(scannedClass.getClassLoader(), () -> {
+ return findParameterizedType(scannedClass, genericType)
+ .map(ptype -> (Class<P>) ptype.getActualTypeArguments()[0]);
+ });
}
- public static ParameterizedType findParameterizedType(final Class<?> subclass, final Class<?> genericType) {
- Preconditions.checkNotNull(subclass);
- Preconditions.checkNotNull(genericType);
+ /**
+ * Find the parameterized instantiation of a particular interface implemented by a class.
+ *
+ * @param subclass Implementing class
+ * @param genericType Interface to search for
+ * @return Parameterized interface as implemented by the class, if present
+ */
+ public static Optional<ParameterizedType> findParameterizedType(final Class<?> subclass,
+ final Class<?> genericType) {
+ requireNonNull(genericType);
for (final Type type : subclass.getGenericInterfaces()) {
- if (type instanceof ParameterizedType && genericType.equals(((ParameterizedType) type).getRawType())) {
- return (ParameterizedType) type;
+ if (type instanceof ParameterizedType) {
+ final ParameterizedType ptype = (ParameterizedType) type;
+ if (genericType.equals(ptype.getRawType())) {
+ return Optional.of(ptype);
+ }
}
}
LOG.debug("Class {} does not declare interface {}", subclass, genericType);
- return null;
+ return Optional.empty();
}
- public static Type getFirstGenericParameter(final Type type) {
- if (type instanceof ParameterizedType) {
- return ((ParameterizedType) type).getActualTypeArguments()[0];
- }
- return null;
+ /**
+ * Extract the first generic type argument for a Type. If the type is not parameterized, this method returns empty.
+ *
+ * @param type Type to examine
+ * @return First generic type argument, if present
+ * @throws NullPointerException if {@code type} is null
+ */
+ public static Optional<Type> getFirstGenericParameter(final Type type) {
+ requireNonNull(type);
+ return type instanceof ParameterizedType ? Optional.of(((ParameterizedType) type).getActualTypeArguments()[0])
+ : Optional.empty();
}
}
Code Review / yangtools.git / blobdiff