yang/yang-binding/src/main/java/org/opendaylight/yangtools/yang/binding/util/ClassLoaderUtils.java

   1 /*
   2  * Copyright (c) 2014 Cisco Systems, Inc. and others.  All rights reserved.
   3  *
   4  * This program and the accompanying materials are made available under the
   5  * terms of the Eclipse Public License v1.0 which accompanies this distribution,
   6  * and is available at http://www.eclipse.org/legal/epl-v10.html
   7  */
   8 package org.opendaylight.yangtools.yang.binding.util;
   9
  10 import static com.google.common.base.Preconditions.checkNotNull;
  11
  12 import java.lang.reflect.Constructor;
  13 import java.lang.reflect.InvocationTargetException;
  14 import java.lang.reflect.ParameterizedType;
  15 import java.lang.reflect.Type;
  16 import java.util.Arrays;
  17 import java.util.List;
  18 import java.util.concurrent.Callable;
  19 import java.util.concurrent.locks.Lock;
  20
  21 import org.slf4j.Logger;
  22 import org.slf4j.LoggerFactory;
  23
  24 import com.google.common.base.Joiner;
  25 import com.google.common.base.Preconditions;
  26 import com.google.common.base.Supplier;
  27
  28 public final class ClassLoaderUtils {
  29     private static final Logger LOG = LoggerFactory.getLogger(ClassLoaderUtils.class);
  30
  31     private ClassLoaderUtils() {
  32         throw new UnsupportedOperationException("Utility class");
  33     }
  34
  35     public static <V> V withClassLoader(final ClassLoader cls, final Supplier<V> function) {
  36         checkNotNull(cls, "Classloader should not be null");
  37         checkNotNull(function, "Function should not be null");
  38
  39         final ClassLoader oldCls = Thread.currentThread().getContextClassLoader();
  40         try {
  41             Thread.currentThread().setContextClassLoader(cls);
  42             return function.get();
  43         } finally {
  44             Thread.currentThread().setContextClassLoader(oldCls);
  45         }
  46     }
  47
  48     public static <V> V withClassLoader(final ClassLoader cls, final Callable<V> function) throws Exception {
  49         checkNotNull(cls, "Classloader should not be null");
  50         checkNotNull(function, "Function should not be null");
  51
  52         final ClassLoader oldCls = Thread.currentThread().getContextClassLoader();
  53         try {
  54             Thread.currentThread().setContextClassLoader(cls);
  55             return function.call();
  56         } finally {
  57             Thread.currentThread().setContextClassLoader(oldCls);
  58         }
  59     }
  60
  61     public static <V> V withClassLoaderAndLock(final ClassLoader cls, final Lock lock, final Supplier<V> function) {
  62         checkNotNull(lock, "Lock should not be null");
  63
  64         lock.lock();
  65         try {
  66             return withClassLoader(cls, function);
  67         } finally {
  68             lock.unlock();
  69         }
  70     }
  71
  72     public static Object construct(final Constructor<? extends Object> constructor, final List<Object> objects)
  73             throws InstantiationException, IllegalAccessException, IllegalArgumentException, InvocationTargetException {
  74         final Object[] initargs = objects.toArray();
  75         return constructor.newInstance(initargs);
  76     }
  77
  78     public static Class<?> loadClass(final ClassLoader cls, final String name) throws ClassNotFoundException {
  79         if ("byte[]".equals(name)) {
  80             return byte[].class;
  81         }
  82         if ("char[]".equals(name)) {
  83             return char[].class;
  84         }
  85
  86         try {
  87             return cls.loadClass(name);
  88         } catch (ClassNotFoundException e) {
  89             String[] components = name.split("\\.");
  90             String potentialOuter;
  91             int length = components.length;
  92             if (length > 2 && (potentialOuter = components[length - 2]) != null && Character.isUpperCase(potentialOuter.charAt(0))) {
  93                     String outerName = Joiner.on(".").join(Arrays.asList(components).subList(0, length - 1));
  94                     String innerName = outerName + "$" + components[length-1];
  95                     return cls.loadClass(innerName);
  96             } else {
  97                 throw e;
  98             }
  99         }
 100     }
 101
 102     public static Class<?> loadClassWithTCCL(final String name) throws ClassNotFoundException {
 103         return loadClass(Thread.currentThread().getContextClassLoader(), name);
 104     }
 105
 106     public static Class<?> tryToLoadClassWithTCCL(final String fullyQualifiedName) {
 107         try {
 108             return loadClassWithTCCL(fullyQualifiedName);
 109         } catch (ClassNotFoundException e) {
 110             LOG.debug("Failed to load class {}", fullyQualifiedName, e);
 111             return null;
 112         }
 113     }
 114
 115     public static <S,G,P> Class<P> findFirstGenericArgument(final Class<S> scannedClass, final Class<G> genericType) {
 116         return withClassLoader(scannedClass.getClassLoader(), ClassLoaderUtils.<S,G,P>findFirstGenericArgumentTask(scannedClass, genericType));
 117     }
 118
 119     private static <S,G,P> Supplier<Class<P>> findFirstGenericArgumentTask(final Class<S> scannedClass, final Class<G> genericType) {
 120         return new Supplier<Class<P>>() {
 121             @Override
 122             @SuppressWarnings("unchecked")
 123             public Class<P> get() {
 124                 final ParameterizedType augmentationGeneric = findParameterizedType(scannedClass, genericType);
 125                 if (augmentationGeneric != null) {
 126                     return (Class<P>) augmentationGeneric.getActualTypeArguments()[0];
 127                 }
 128                 return null;
 129             }
 130         };
 131     }
 132
 133     public static ParameterizedType findParameterizedType(final Class<?> subclass, final Class<?> genericType) {
 134         Preconditions.checkNotNull(subclass);
 135         Preconditions.checkNotNull(genericType);
 136
 137         for (Type type : subclass.getGenericInterfaces()) {
 138             if (type instanceof ParameterizedType && genericType.equals(((ParameterizedType) type).getRawType())) {
 139                 return (ParameterizedType) type;
 140             }
 141         }
 142
 143         LOG.debug("Class {} does not declare interface {}", subclass, genericType);
 144         return null;
 145     }
 146
 147     public static Type getFirstGenericParameter(final Type type) {
 148         if (type instanceof ParameterizedType) {
 149             return ((ParameterizedType) type).getActualTypeArguments()[0];
 150         }
 151         return null;
 152     }
 153 }