让kryo支持反序列化没有无参构造方法的类
动态得到类的实例，我们通常通过反射来得到。但有时候，类缺少默认构造方法，我们又不想传参来实例化，这时候怎么办呢？
我们还可以通过sun.reflect.ReflectionFactory来完成，例子如下：
import java.lang.reflect.Constructor;import java.util.concurrent.ConcurrentHashMap;import sun.reflect.ReflectionFactory;import com.esotericsoftware.kryo.Kryo;public class Kryox extends Kryo {private final ReflectionFactory REFLECTION_FACTORY = ReflectionFactory.getReflectionFactory();private final ConcurrentHashMap<Class<?>, Constructor<?>> _constructors = new ConcurrentHashMap<Class<?>, Constructor<?>>();@Overridepublic <T> T newInstance(Class<T> type) {try {return super.newInstance(type);} catch (Exception e) {return (T) newInstanceFromReflectionFactory(type);}}private Object newInstanceFrom(Constructor<?> constructor) {try {return constructor.newInstance();} catch (final Exception e) {throw new RuntimeException(e);}}@SuppressWarnings("unchecked")public <T> T newInstanceFromReflectionFactory(Class<T> type) {Constructor<?> constructor = _constructors.get(type);if (constructor == null) {constructor = newConstructorForSerialization(type);Constructor<?> saved = _constructors.putIfAbsent(type, constructor);if(saved!=null)constructor=saved;}return (T) newInstanceFrom(constructor);}private <T> Constructor<?> newConstructorForSerialization(Class<T> type) {try {Constructor<?> constructor = REFLECTION_FACTORY.newConstructorForSerialization(type,Object.class.getDeclaredConstructor());constructor.setAccessible(true);return constructor;} catch (Exception e) {throw new RuntimeException(e);}}}