/*
* Copyright (c) 2013, OpenCloudDB/MyCAT and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software;Designed and Developed mainly by many Chinese
* opensource volunteers. you can redistribute it and/or modify it under the
* terms of the GNU General Public License version 2 only, as published by the
* Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Any questions about this component can be directed to it's project Web address
* https://code.google.com/p/opencloudb/.
*
*/
package org.opencloudb.config.util;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectStreamClass;
import java.io.ObjectStreamConstants;
import java.io.Serializable;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
/**
* @author mycat
*/
public class ReflectionProvider {
private transient Map<Class<?>, byte[]> serializedDataCache = Collections
.synchronizedMap(new HashMap<Class<?>, byte[]>());
private transient FieldDictionary fieldDictionary = new FieldDictionary();
public Object newInstance(Class<?> type) {
try {
Constructor<?>[] c = type.getDeclaredConstructors();
for (int i = 0; i < c.length; i++) {
if (c[i].getParameterTypes().length == 0) {
if (!Modifier.isPublic(c[i].getModifiers())) {
c[i].setAccessible(true);
}
return c[i].newInstance(new Object[0]);
}
}
if (Serializable.class.isAssignableFrom(type)) {
return instantiateUsingSerialization(type);
} else {
throw new ObjectAccessException("Cannot construct " + type.getName()
+ " as it does not have a no-args constructor");
}
} catch (InstantiationException e) {
throw new ObjectAccessException("Cannot construct " + type.getName(), e);
} catch (IllegalAccessException e) {
throw new ObjectAccessException("Cannot construct " + type.getName(), e);
} catch (InvocationTargetException e) {
if (e.getTargetException() instanceof RuntimeException) {
throw (RuntimeException) e.getTargetException();
} else if (e.getTargetException() instanceof Error) {
throw (Error) e.getTargetException();
} else {
throw new ObjectAccessException("Constructor for " + type.getName() + " threw an exception",
e.getTargetException());
}
}
}
public void visitSerializableFields(Object object, Visitor visitor) {
for (Iterator<Field> iterator = fieldDictionary.serializableFieldsFor(object.getClass()); iterator.hasNext();) {
Field field = iterator.next();
if (!fieldModifiersSupported(field)) {
continue;
}
validateFieldAccess(field);
try {
Object value = field.get(object);
visitor.visit(field.getName(), field.getType(), field.getDeclaringClass(), value);
} catch (IllegalArgumentException e) {
throw new ObjectAccessException("Could not get field " + field.getClass() + "." + field.getName(), e);
} catch (IllegalAccessException e) {
throw new ObjectAccessException("Could not get field " + field.getClass() + "." + field.getName(), e);
}
}
}
public void writeField(Object object, String fieldName, Object value, Class<?> definedIn) {
Field field = fieldDictionary.field(object.getClass(), fieldName, definedIn);
validateFieldAccess(field);
try {
field.set(object, value);
} catch (IllegalArgumentException e) {
throw new ObjectAccessException("Could not set field " + field.getName() + "@" + object.getClass(), e);
} catch (IllegalAccessException e) {
throw new ObjectAccessException("Could not set field " + field.getName() + "@" + object.getClass(), e);
}
}
public void invokeMethod(Object object, String methodName, Object value, Class<?> definedIn) {
try {
Method method = object.getClass().getMethod(methodName, new Class[] { value.getClass() });
method.invoke(object, new Object[] { value });
} catch (Exception e) {
throw new ObjectAccessException("Could not invoke " + object.getClass() + "." + methodName, e);
}
}
public Class<?> getFieldType(Object object, String fieldName, Class<?> definedIn) {
return fieldDictionary.field(object.getClass(), fieldName, definedIn).getType();
}
public boolean fieldDefinedInClass(String fieldName, Class<?> type) {
try {
Field field = fieldDictionary.field(type, fieldName, null);
return fieldModifiersSupported(field);
} catch (ObjectAccessException e) {
return false;
}
}
public Field getField(Class<?> definedIn, String fieldName) {
return fieldDictionary.field(definedIn, fieldName, null);
}
private Object instantiateUsingSerialization(Class<?> type) {
try {
byte[] data;
if (serializedDataCache.containsKey(type)) {
data = serializedDataCache.get(type);
} else {
ByteArrayOutputStream bytes = new ByteArrayOutputStream();
DataOutputStream stream = new DataOutputStream(bytes);
stream.writeShort(ObjectStreamConstants.STREAM_MAGIC);
stream.writeShort(ObjectStreamConstants.STREAM_VERSION);
stream.writeByte(ObjectStreamConstants.TC_OBJECT);
stream.writeByte(ObjectStreamConstants.TC_CLASSDESC);
stream.writeUTF(type.getName());
stream.writeLong(ObjectStreamClass.lookup(type).getSerialVersionUID());
stream.writeByte(2); // classDescFlags (2 = Serializable)
stream.writeShort(0); // field count
stream.writeByte(ObjectStreamConstants.TC_ENDBLOCKDATA);
stream.writeByte(ObjectStreamConstants.TC_NULL);
data = bytes.toByteArray();
serializedDataCache.put(type, data);
}
ObjectInputStream in = new ObjectInputStream(new ByteArrayInputStream(data));
return in.readObject();
} catch (IOException e) {
throw new ObjectAccessException("Cannot create " + type.getName() + " by JDK serialization", e);
} catch (ClassNotFoundException e) {
throw new ObjectAccessException("Cannot find class " + e.getMessage());
}
}
private boolean fieldModifiersSupported(Field field) {
return !(Modifier.isStatic(field.getModifiers()) || Modifier.isTransient(field.getModifiers()));
}
private void validateFieldAccess(Field field) {
if (Modifier.isFinal(field.getModifiers())) {
if (JVMInfo.is15()) {
field.setAccessible(true);
} else {
throw new ObjectAccessException("Invalid final field " + field.getDeclaringClass().getName() + "."
+ field.getName());
}
}
}
private Object readResolve() {
serializedDataCache = Collections.synchronizedMap(new HashMap<Class<?>, byte[]>());
fieldDictionary = new FieldDictionary();
return this;
}
}