Add a default registration if missing Class structure when re…

src/com/esotericsoftware/kryo/serializers/CompatibleFieldSerializer.java

@@ -135,9 +135,14 @@ public T read (Kryo kryo, Input input, Class<? extends T> type) {
 				} catch (KryoException ex) {
 					String message = "Unable to read unknown data (unknown type). (" + getType().getName() + "#" + cachedField + ")";
 					if (!chunked) throw new KryoException(message, ex);
-					if (DEBUG) debug("kryo", message, ex);
-					inputChunked.nextChunk();
-					continue;
+					try {
+						//try to give a default registration
+						registration = kryo.getRegistration(Object.class);
+					} catch (Exception e) {
+						if(DEBUG) trace("Unable to get default registration: " + e.getMessage());
+						inputChunked.nextChunk();
+						continue;
+					}
 				}
 				if (registration == null) {
 					if (chunked) inputChunked.nextChunk();

test/com/esotericsoftware/kryo/serializers/ClassStructureTest.java

@@ -0,0 +1,103 @@
+package com.esotericsoftware.kryo.serializers;
+
+import com.esotericsoftware.kryo.Kryo;
+import com.esotericsoftware.kryo.KryoTestCase;
+import com.esotericsoftware.kryo.SerializerFactory;
+import com.esotericsoftware.kryo.io.Input;
+import com.esotericsoftware.kryo.io.Output;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+
+/**
+ * You need run encode() first. And then run decode() follow instruction.
+ *
+ * Create by maxisvest
+ * 2019/7/25 14:20
+ */
+public class ClassStructureTest extends KryoTestCase {
+
+    public static final Kryo kryo = new Kryo();
+
+    @Before
+    public void setUp () throws Exception {
+        super.setUp();
+        SerializerFactory.CompatibleFieldSerializerFactory compatibleFieldSerializerFactory = new SerializerFactory.CompatibleFieldSerializerFactory();
+        CompatibleFieldSerializer.CompatibleFieldSerializerConfig config = compatibleFieldSerializerFactory.getConfig();
+        kryo.setDefaultSerializer(compatibleFieldSerializerFactory);
+        kryo.setRegistrationRequired(false);
+
+        //this case use for enable references and chunked encoding
+        kryo.setReferences(true);
+        config.setChunkedEncoding(true);
+    }
+
+    /**
+     * Run this method first, to write a full version instance of class DataBean.
+     *
+     * DataBean include SubData and SubData include the String message.
+     * If enable kryo.references function, String message in SubData will write first and this String in
+     * DataBean will write as a reference.
+     *
+     * Imagine this procedure is the server want to transfer data to client.
+     * @throws IOException
+     */
+    @Test
+    public void encode() throws IOException {
+        String message = "Hello Kryo!";
+
+        SubData subData = new SubData(); //delete on decode test
+        subData.message = message; //delete on decode test
+
+        DataBean dataBean = new DataBean();
+        dataBean.aSubData = subData; //delete on decode test
+        dataBean.message = message;
+
+        Output output = new Output(new FileOutputStream("file_y.bin"));
+        kryo.writeObject(output, dataBean);
+        output.close();
+    }
+
+    /**
+     * Before run this method, you need delete the line and Class SubData marked as "delete on decode test". The Class DataBean only
+     * have the field String message.
+     *
+     * Imagine this is the client want to deserialize the data come from server. But client use the old version of Class DataBean.
+     *
+     * Normally, decode() will throw an Exception because it can not find the referenced value of String message. The String message
+     * referenced value is in the chunked input but it has been skipped.
+     * Use PR #686 will solve this problem and recover the String message in DataBean. Therefore run decode() will pass now.
+     *
+     * @throws IOException
+     */
+    @Test
+    public void decode() throws IOException {
+        File file = new File("file_y.bin");
+        if (file.exists()) {
+            Input input = new Input(new FileInputStream(file));
+            DataBean dataBean = kryo.readObject(input, DataBean.class);
+            file.delete();
+            input.close();
+        }
+    }
+
+
+
+    static public class DataBean {
+       SubData aSubData; //delete on decode test
+       String message;
+    }
+
+    //delete on decode test
+    static public class SubData {
+        String message;
+    }
+
+
+
+
+}