com.cedarsoftware.io.Unsafe Maven / Gradle / Ivy
package com.cedarsoftware.io;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import static com.cedarsoftware.io.MetaUtils.trySetAccessible;
import static com.cedarsoftware.util.ClassUtilities.forName;
/**
* Wrapper for unsafe, decouples direct usage of sun.misc.* package.
* @author Kai Hufenback
*/
final class Unsafe
{
private final Object sunUnsafe;
private final Method allocateInstance;
/**
* Constructs unsafe object, acting as a wrapper.
* @throws InvocationTargetException
*/
public Unsafe() throws InvocationTargetException {
try {
Constructor unsafeConstructor = forName("sun.misc.Unsafe", MetaUtils.class.getClassLoader()).getDeclaredConstructor();
trySetAccessible(unsafeConstructor);
sunUnsafe = unsafeConstructor.newInstance();
allocateInstance = sunUnsafe.getClass().getMethod("allocateInstance", Class.class);
trySetAccessible(allocateInstance);
}
catch (Exception e) {
throw new JsonIoException("Unable to use sun.misc.Unsafe to construct objects.", e);
}
}
/**
* Creates an object without invoking constructor or initializing variables.
* Be careful using this with JDK objects, like URL or ConcurrentHashMap this may bring your VM into troubles.
* @param clazz to instantiate
* @return allocated Object
*/
public Object allocateInstance(Class clazz)
{
try {
return allocateInstance.invoke(sunUnsafe, clazz);
}
catch (IllegalAccessException | IllegalArgumentException e ) {
String name = clazz == null ? "null" : clazz.getName();
throw new JsonIoException("Unable to create instance of class: " + name, e);
}
catch (InvocationTargetException e) {
String name = clazz == null ? "null" : clazz.getName();
throw new JsonIoException("Unable to create instance of class: " + name, e.getCause() != null ? e.getCause() : e);
}
}
}