needed for graph tests

src/main/java/org/springframework/persistence/support/AbstractConstructorEntityInstantiator.java

@@ -0,0 +1,61 @@
+package org.springframework.persistence.support;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.InvocationTargetException;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.springframework.util.ClassUtils;
+
+/**
+ * Try for a constructor taking state: failing that, try a no-arg
+ * constructor and then setUnderlyingNode().
+ * 
+ * @author Rod Johnson
+ */
+public abstract class AbstractConstructorEntityInstantiator<BACKING_INTERFACE, STATE> implements EntityInstantiator<BACKING_INTERFACE, STATE> {
+	
+	private final Log log = LogFactory.getLog(getClass());
+	
+	final public <T extends BACKING_INTERFACE> T createEntityFromState(STATE n, Class<T> c) {
+		try {
+			return fromStateInternal(n, c);
+		}  catch (InstantiationException e) {
+			throw new IllegalArgumentException(e);
+		} catch (IllegalAccessException e) {
+			throw new IllegalArgumentException(e);
+		} catch (InvocationTargetException e) {
+			throw new IllegalArgumentException(e);
+		}
+	}
+
+	final private <T extends BACKING_INTERFACE> T fromStateInternal(STATE n, Class<T> c) throws IllegalArgumentException, InstantiationException, IllegalAccessException, InvocationTargetException {
+		// TODO this is fragile
+		Class<? extends STATE> stateInterface = (Class<? extends STATE>) n.getClass().getInterfaces()[0];
+		Constructor<T> nodeConstructor = ClassUtils.getConstructorIfAvailable(c, stateInterface);
+		if (nodeConstructor != null) {
+			// TODO is this the correct way to instantiate or does Spring have a preferred way?
+			log.info("Using " + c + " constructor taking " + stateInterface);
+ 			return nodeConstructor.newInstance(n);
+		}
+		
+		Constructor<T> noArgConstructor = ClassUtils.getConstructorIfAvailable(c);
+		if (noArgConstructor != null) {
+			log.info("Using " + c + " no-arg constructor");
+			T t = noArgConstructor.newInstance();
+			setState(t, n);
+			return t;
+		}
+		
+		throw new IllegalArgumentException(getClass().getSimpleName() + ": entity " + c + " must have either a constructor taking [" + stateInterface + 
+				"] or a no-arg constructor and state set method");
+	}
+	
+	/**
+	 * Subclasses must implement to set state
+	 * @param entity
+	 * @param s
+	 */
+	protected abstract void setState(BACKING_INTERFACE entity, STATE s);
+
+}