package com.google.gson.internal;
import java.io.ObjectInputStream;
import java.io.ObjectStreamClass;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
public abstract class UnsafeAllocator {
public abstract <T> T newInstance(Class<T> c) throws Exception;
public static UnsafeAllocator create() {
try {
Class<?> unsafeClass = Class.forName("sun.misc.Unsafe");
Field f = unsafeClass.getDeclaredField("theUnsafe");
f.setAccessible(true);
final Object unsafe = f.get(null);
final Method allocateInstance = unsafeClass.getMethod("allocateInstance", Class.class);
return new UnsafeAllocator() {
@Override
@SuppressWarnings("unchecked")
public <T> T newInstance(Class<T> c) throws Exception {
assertInstantiable(c);
return (T) allocateInstance.invoke(unsafe, c);
}
};
} catch (Exception ignored) {
}
try {
Method getConstructorId = ObjectStreamClass.class
.getDeclaredMethod("getConstructorId", Class.class);
getConstructorId.setAccessible(true);
final int constructorId = (Integer) getConstructorId.invoke(null, Object.class);
final Method newInstance = ObjectStreamClass.class
.getDeclaredMethod("newInstance", Class.class, int.class);
newInstance.setAccessible(true);
return new UnsafeAllocator() {
@Override
@SuppressWarnings("unchecked")
public <T> T newInstance(Class<T> c) throws Exception {
assertInstantiable(c);
return (T) newInstance.invoke(null, c, constructorId);
}
};
} catch (Exception ignored) {
}
try {
final Method newInstance = ObjectInputStream.class
.getDeclaredMethod("newInstance", Class.class, Class.class);
newInstance.setAccessible(true);
return new UnsafeAllocator() {
@Override
@SuppressWarnings("unchecked")
public <T> T newInstance(Class<T> c) throws Exception {
assertInstantiable(c);
return (T) newInstance.invoke(null, c, Object.class);
}
};
} catch (Exception ignored) {
}
return new UnsafeAllocator() {
@Override
public <T> T newInstance(Class<T> c) {
throw new UnsupportedOperationException("Cannot allocate " + c);
}
};
}
static void assertInstantiable(Class<?> c) {
int modifiers = c.getModifiers();
if (Modifier.isInterface(modifiers)) {
throw new UnsupportedOperationException("Interface can't be instantiated! Interface name: " + c.getName());
}
if (Modifier.isAbstract(modifiers)) {
throw new UnsupportedOperationException("Abstract class can't be instantiated! Class name: " + c.getName());
}
}
}