Move the changes for hibernate 5.2 compatibility to class

ProxySessionReader

Author: mshima

hibernate5/src/main/java/com/fasterxml/jackson/datatype/hibernate5/HibernateProxySerializer.java

@@ -18,6 +18,7 @@
 import com.fasterxml.jackson.databind.ser.impl.PropertySerializerMap;
 
 import org.hibernate.engine.spi.Mapping;
+import org.hibernate.engine.spi.SessionFactoryImplementor;
 import org.hibernate.engine.spi.SessionImplementor;
 import org.hibernate.proxy.HibernateProxy;
 import org.hibernate.proxy.LazyInitializer;
@@ -45,15 +46,6 @@ public class HibernateProxySerializer
     protected final boolean _serializeIdentifier;
     protected final Mapping _mapping;
 
-    /**
-     * Flag to keep track if hibernate abi running is not
-     * compatible with hibernate jackson-datatype-hibernate5
-     * used at build-time.
-     * Maybe using org.hibernate.Version is a better solution
-     * but the build time version is needed too.
-     */
-    protected Boolean hibernateAbiIncompatible;
-
     /**
      * For efficient serializer lookup, let's use this; most
      * of the time, there's just one type and one serializer.
@@ -191,30 +183,8 @@ protected Object findProxied(HibernateProxy proxy)
                 if (_mapping != null) {
                     idName = _mapping.getIdentifierPropertyName(init.getEntityName());
                 } else {
-                    // Detect abi compatibility if not set yet
-                    if(hibernateAbiIncompatible == null){
-                        try {
-                            init.getSession();
-                            hibernateAbiIncompatible = false;
-                        } catch (NoSuchMethodError e) {
-                            hibernateAbiIncompatible = true;
-                        }
-                    }
-                    final Object sessionObj;
-                    if(!hibernateAbiIncompatible){
-                        sessionObj = init.getSession();
-                    }else{
-                        try {
-                            Method method = init.getClass().getMethod("getSession");
-                            sessionObj = method.invoke(init);
-                        } catch (Exception e1) {
-                            throw new RuntimeException(e1);
-                        }
-                    }
-                    if (sessionObj != null) {
-                        final SessionImplementor session = (org.hibernate.engine.spi.SessionImplementor) sessionObj;
-                        idName = session.getFactory().getIdentifierPropertyName(init.getEntityName());
-                    } else {
+                    idName = ProxySessionReader.getIdentifierPropertyName(init);
+                    if (idName == null) {
                         idName = ProxyReader.getIdentifierPropertyName(init);
                         if (idName == null) {
                         	idName = init.getEntityName();
@@ -271,4 +241,50 @@ static String getIdentifierPropertyName(LazyInitializer init) {
             }
         }
     }
+    
+    /**
+     * Hibernate 5.2 broke abi compatibility of org.hibernate.proxy.LazyInitializer.getSession()
+     * The api contract changed
+     * from org.hibernate.proxy.LazyInitializer.getSession()Lorg.hibernate.engine.spi.SessionImplementor;
+     * to org.hibernate.proxy.LazyInitializer.getSession()Lorg.hibernate.engine.spi.SharedSessionContractImplementor
+     * 
+     * On hibernate 5.2 the interface SessionImplementor extends SharedSessionContractImplementor.
+     * And an instance of org.hibernate.internal.SessionImpl is returned from getSession().
+     */
+    protected static class ProxySessionReader {
+    	
+    	/**
+    	 * The getSession method must be executed using reflection for compatibility purpose.
+    	 * For efficiency keep the method cached.
+    	 */
+        protected static final Method lazyInitializerGetSessionMethod;
+        
+        static {
+            try {
+                lazyInitializerGetSessionMethod = LazyInitializer.class.getMethod("getSession");
+            } catch (Exception e) {
+                // should never happen: the class and method exists in all versions of hibernate 5
+                throw new RuntimeException(e); 
+            }
+        }
+        
+        static String getIdentifierPropertyName(LazyInitializer init) {
+            final Object session;
+            try{
+                session = lazyInitializerGetSessionMethod.invoke(init);
+            } catch (Exception e) {
+                // Should never happen
+                throw new RuntimeException(e);
+            }
+            if(session instanceof SessionImplementor){
+            	SessionFactoryImplementor factory = ((SessionImplementor)session).getFactory();
+            	return factory.getIdentifierPropertyName(init.getEntityName());
+            }else if (session != null) {
+                // Should never happen: session should be an instance of org.hibernate.internal.SessionImpl
+                // factory = session.getClass().getMethod("getFactory").invoke(session);
+                throw new RuntimeException("Session is not instance of SessionImplementor");
+            }
+            return null;
+        }
+    }
 }