org.activiti.engine.impl.util.ReflectUtil Maven / Gradle / Ivy
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/* 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.Locale;
import java.util.regex.Pattern;
import org.activiti.engine.ActivitiClassLoadingException;
import org.activiti.engine.ActivitiException;
import org.activiti.engine.impl.cfg.ProcessEngineConfigurationImpl;
import org.activiti.engine.impl.context.Context;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* @author Tom Baeyens
*/
public abstract class ReflectUtil {
private static final Logger LOG = LoggerFactory.getLogger(ReflectUtil.class);
private static final Pattern GETTER_PATTERN = Pattern.compile("(get|is)[A-Z].*");
private static final Pattern SETTER_PATTERN = Pattern.compile("set[A-Z].*");
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.trace("Trying to load class with custom classloader: {}", className);
clazz = loadClass(classLoader, className);
} catch(Throwable t) {
throwable = t;
}
}
if(clazz == null) {
try {
LOG.trace("Trying to load class with current thread context classloader: {}", className);
clazz = loadClass(Thread.currentThread().getContextClassLoader(), className);
} catch(Throwable t) {
if(throwable == null) {
throwable = t;
}
}
if(clazz == null) {
try {
LOG.trace("Trying to load class with local classloader: {}", className);
clazz = loadClass(ReflectUtil.class.getClassLoader(), className);
} 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 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 Constructor findMatchingConstructor(Class clazz, Object[] args) {
for (Constructor constructor: clazz.getDeclaredConstructors()) { // cannot use or 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 type = method.getReturnType();
Class< ? > params[] = method.getParameterTypes();
if (!GETTER_PATTERN.matcher(name).matches()) {
return false;
}
// special for isXXX boolean
if (name.startsWith("is")) {
return params.length == 0 && type.getSimpleName().equalsIgnoreCase("boolean");
}
return params.length == 0 && !type.equals(Void.TYPE);
}
public static boolean isSetter(Method method, boolean allowBuilderPattern) {
String name = method.getName();
Class< ? > type = method.getReturnType();
Class< ? > params[] = method.getParameterTypes();
if (!SETTER_PATTERN.matcher(name).matches()) {
return false;
}
return params.length == 1 && (type.equals(Void.TYPE) || (allowBuilderPattern && method.getDeclaringClass().isAssignableFrom(type)));
}
public static boolean isSetter(Method method) {
return isSetter(method, false);
}
public static String getGetterShorthandName(Method method) {
if (!isGetter(method)) {
return method.getName();
}
String name = method.getName();
if (name.startsWith("get")) {
name = name.substring(3);
name = name.substring(0, 1).toLowerCase(Locale.ENGLISH) + name.substring(1);
} else if (name.startsWith("is")) {
name = name.substring(2);
name = name.substring(0, 1).toLowerCase(Locale.ENGLISH) + name.substring(1);
}
return name;
}
public static String getSetterShorthandName(Method method) {
if (!isSetter(method)) {
return method.getName();
}
String name = method.getName();
if (name.startsWith("set")) {
name = name.substring(3);
name = name.substring(0, 1).toLowerCase(Locale.ENGLISH) + name.substring(1);
}
return name;
}
}