OO-1226: bypass serialVersionUID from qti.ser, only write a warn if not ok

src/main/java/org/olat/ims/qti/process/DecompressibleInputStream.java

+/**
+ * <a href="http://www.openolat.org">
+ * OpenOLAT - Online Learning and Training</a><br>
+ * <p>
+ * Licensed under the Apache License, Version 2.0 (the "License"); <br>
+ * you may not use this file except in compliance with the License.<br>
+ * You may obtain a copy of the License at the
+ * <a href="http://www.apache.org/licenses/LICENSE-2.0">Apache homepage</a>
+ * <p>
+ * Unless required by applicable law or agreed to in writing,<br>
+ * software distributed under the License is distributed on an "AS IS" BASIS, <br>
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. <br>
+ * See the License for the specific language governing permissions and <br>
+ * limitations under the License.
+ * <p>
+ * Initial code contributed and copyrighted by<br>
+ * frentix GmbH, http://www.frentix.com
+ * <p>
+ */
+package org.olat.ims.qti.process;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InvalidClassException;
+import java.io.ObjectInputStream;
+import java.io.ObjectStreamClass;
+
+import org.olat.core.logging.OLog;
+import org.olat.core.logging.Tracing;
+
+/**
+ * 
+ * http://stackoverflow.com/questions/795470/how-to-deserialize-an-object-persisted-in-a-db-now-when-the-object-has-different
+ * 
+ * @author jorge, java forums
+ *
+ */
+public class DecompressibleInputStream extends ObjectInputStream {
+	
+	private static final OLog log = Tracing.createLoggerFor(DecompressibleInputStream.class);
+
+    public DecompressibleInputStream(InputStream in) throws IOException {
+        super(in);
+    }
+
+    @Override
+    protected ObjectStreamClass readClassDescriptor() throws IOException, ClassNotFoundException {
+        ObjectStreamClass resultClassDescriptor = super.readClassDescriptor(); // initially streams descriptor
+        Class<?> localClass = Class.forName(resultClassDescriptor.getName()); // the class in the local JVM that this descriptor represents.
+        if (localClass == null) {
+            log.error("No local class for " + resultClassDescriptor.getName());
+            return resultClassDescriptor;
+        }
+        ObjectStreamClass localClassDescriptor = ObjectStreamClass.lookup(localClass);
+        if (localClassDescriptor != null) { // only if class implements serializable
+            final long localSUID = localClassDescriptor.getSerialVersionUID();
+            final long streamSUID = resultClassDescriptor.getSerialVersionUID();
+            if (streamSUID != localSUID) { // check for serialVersionUID mismatch.
+                final StringBuilder s = new StringBuilder("Overriding serialized class version mismatch: ");
+                s.append("local serialVersionUID = ").append(localSUID).append(" stream serialVersionUID = ").append(streamSUID);
+                Exception e = new InvalidClassException(s.toString());
+                log.warn(s.toString(), e);
+                resultClassDescriptor = localClassDescriptor;
+            }
+        }
+        return resultClassDescriptor;
+    }
+}

src/main/java/org/olat/ims/qti/process/FilePersister.java

@@ -156,7 +156,7 @@ public class FilePersister implements Persister {
 			}
 			is = new FileInputStream(new File(fSerialDir, QTI_FILE));
 			BufferedInputStream bis = new BufferedInputStream(is, 262144);
-			ObjectInputStream oistream = new ObjectInputStream(bis);
+			ObjectInputStream oistream = new DecompressibleInputStream(bis);
 			o = oistream.readObject();
 			oistream.close();
 			is.close();
@@ -166,6 +166,7 @@ public class FilePersister implements Persister {
 			}
 
 		} catch (Exception e) {
+			log.error("", e);
 			try {
 				if (is != null) is.close();
 			} catch (IOException e1) {