/* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.activiti.engine.impl.util;
import java.io.InputStream;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.net.URL;
import java.util.Arrays;
import java.util.logging.Logger;
import org.activiti.engine.ActivitiClassLoadingException;
import org.activiti.engine.ActivitiException;
import org.activiti.engine.impl.cfg.ProcessEngineConfigurationImpl;
import org.activiti.engine.impl.context.Context;
/**
* @author Tom Baeyens
*/
public abstract class ReflectUtil {
private static final Logger LOG = Logger.getLogger(ReflectUtil.class.getName());
public static ClassLoader getClassLoader() {
ClassLoader loader = getCustomClassLoader();
if(loader == null) {
loader = Thread.currentThread().getContextClassLoader();
}
return loader;
}
public static Class<?> loadClass(String className) {
Class<?> clazz = null;
ClassLoader classLoader = getCustomClassLoader();
// First exception in chain of classloaders will be used as cause when no class is found in any of them
Throwable throwable = null;
if(classLoader != null) {
try {
LOG.finest("Trying to load class with custom classloader: " + className);
clazz = Class.forName(className, true, classLoader);
} catch(Throwable t) {
throwable = t;
}
}
if(clazz == null) {
try {
LOG.finest("Trying to load class with current thread context classloader: " + className);
clazz = Class.forName(className, true, Thread.currentThread().getContextClassLoader());
} catch(Throwable t) {
if(throwable == null) {
throwable = t;
}
}
if(clazz == null) {
try {
LOG.finest("Trying to load class with local classloader: " + className);
clazz = Class.forName(className, true, ReflectUtil.class.getClassLoader());
} catch(Throwable t) {
if(throwable == null) {
throwable = t;
}
}
}
}
if(clazz == null) {
throw new ActivitiClassLoadingException(className, throwable);
}
return clazz;
}
public static InputStream getResourceAsStream(String name) {
InputStream resourceStream = null;
ClassLoader classLoader = getCustomClassLoader();
if(classLoader != null) {
resourceStream = classLoader.getResourceAsStream(name);
}
if(resourceStream == null) {
// Try the current Thread context classloader
classLoader = Thread.currentThread().getContextClassLoader();
resourceStream = classLoader.getResourceAsStream(name);
if(resourceStream == null) {
// Finally, try the classloader for this class
classLoader = ReflectUtil.class.getClassLoader();
resourceStream = classLoader.getResourceAsStream(name);
}
}
return resourceStream;
}
public static URL getResource(String name) {
URL url = null;
ClassLoader classLoader = getCustomClassLoader();
if(classLoader != null) {
url = classLoader.getResource(name);
}
if(url == null) {
// Try the current Thread context classloader
classLoader = Thread.currentThread().getContextClassLoader();
url = classLoader.getResource(name);
if(url == null) {
// Finally, try the classloader for this class
classLoader = ReflectUtil.class.getClassLoader();
url = classLoader.getResource(name);
}
}
return url;
}
public static Object instantiate(String className) {
try {
Class< ? > clazz = loadClass(className);
return clazz.newInstance();
} catch (Exception e) {
throw new ActivitiException("couldn't instantiate class "+className, e);
}
}
public static Object invoke(Object target, String methodName, Object[] args) {
try {
Class<? extends Object> clazz = target.getClass();
Method method = findMethod(clazz, methodName, args);
method.setAccessible(true);
return method.invoke(target, args);
} catch (Exception e) {
throw new ActivitiException("couldn't invoke "+methodName+" on "+target, e);
}
}
/**
* Returns the field of the given object or null if it doesnt exist.
*/
public static Field getField(String fieldName, Object object) {
return getField(fieldName, object.getClass());
}
/**
* Returns the field of the given class or null if it doesnt exist.
*/
public static Field getField(String fieldName, Class<?> clazz) {
Field field = null;
try {
field = clazz.getDeclaredField(fieldName);
} catch (SecurityException e) {
throw new ActivitiException("not allowed to access field " + field + " on class " + clazz.getCanonicalName());
} catch (NoSuchFieldException e) {
// for some reason getDeclaredFields doesnt search superclasses
// (which getFields() does ... but that gives only public fields)
Class<?> superClass = clazz.getSuperclass();
if (superClass != null) {
return getField(fieldName, superClass);
}
}
return field;
}
public static void setField(Field field, Object object, Object value) {
try {
field.setAccessible(true);
field.set(object, value);
} catch (IllegalArgumentException e) {
throw new ActivitiException("Could not set field " + field.toString(), e);
} catch (IllegalAccessException e) {
throw new ActivitiException("Could not set field " + field.toString(), e);
}
}
/**
* Returns the setter-method for the given field name or null if no setter exists.
*/
public static Method getSetter(String fieldName, Class<?> clazz, Class<?> fieldType) {
String setterName = "set" + Character.toTitleCase(fieldName.charAt(0)) +
fieldName.substring(1, fieldName.length());
try {
// Using getMathods(), getMathod(...) expects exact parameter type
// matching and ignores inheritance-tree.
Method[] methods = clazz.getMethods();
for(Method method : methods) {
if(method.getName().equals(setterName)) {
Class<?>[] paramTypes = method.getParameterTypes();
if(paramTypes != null && paramTypes.length == 1 && paramTypes[0].isAssignableFrom(fieldType)) {
return method;
}
}
}
return null;
} catch (SecurityException e) {
throw new ActivitiException("Not allowed to access method " + setterName + " on class " + clazz.getCanonicalName());
}
}
private static Method findMethod(Class< ? extends Object> clazz, String methodName, Object[] args) {
for (Method method : clazz.getDeclaredMethods()) {
// TODO add parameter matching
if ( method.getName().equals(methodName)
&& matches(method.getParameterTypes(), args)
) {
return method;
}
}
Class< ? > superClass = clazz.getSuperclass();
if (superClass!=null) {
return findMethod(superClass, methodName, args);
}
return null;
}
public static Object instantiate(String className, Object[] args) {
Class< ? > clazz = loadClass(className);
Constructor< ? > constructor = findMatchingConstructor(clazz, args);
if (constructor==null) {
throw new ActivitiException("couldn't find constructor for "+className+" with args "+Arrays.asList(args));
}
try {
return constructor.newInstance(args);
} catch (Exception e) {
throw new ActivitiException("couldn't find constructor for "+className+" with args "+Arrays.asList(args), e);
}
}
@SuppressWarnings({ "unchecked", "rawtypes" })
private static <T> Constructor<T> findMatchingConstructor(Class<T> clazz, Object[] args) {
for (Constructor constructor: clazz.getDeclaredConstructors()) { // cannot use <?> or <T> due to JDK 5/6 incompatibility
if (matches(constructor.getParameterTypes(), args)) {
return constructor;
}
}
return null;
}
private static boolean matches(Class< ? >[] parameterTypes, Object[] args) {
if ( (parameterTypes==null)
|| (parameterTypes.length==0)
) {
return ( (args==null)
|| (args.length==0)
);
}
if ( (args==null)
|| (parameterTypes.length!=args.length)
) {
return false;
}
for (int i=0; i<parameterTypes.length; i++) {
if ( (args[i]!=null)
&& (! parameterTypes[i].isAssignableFrom(args[i].getClass()))
) {
return false;
}
}
return true;
}
private static ClassLoader getCustomClassLoader() {
ProcessEngineConfigurationImpl processEngineConfiguration = Context.getProcessEngineConfiguration();
if(processEngineConfiguration != null) {
final ClassLoader classLoader = processEngineConfiguration.getClassLoader();
if(classLoader != null) {
return classLoader;
}
}
return null;
}
}