Use references in RepositoryTransition

- Refactor so that we can create RepositoryState in one place
  and then reference to it from JpaRepositoryTransition impls.
- New common top class BaseRepositoryEntity for entities
- Change RepositoryState and RepositoryTransition to be abstract
  classes instead of interfaces.
- New custom StateMachineJackson2RepositoryPopulatorFactoryBean and
  StateMachineJackson2ResourceReader handling json refs.
- Relates to #262

spring-statemachine-data/src/main/java/org/springframework/statemachine/data/BaseRepositoryEntity.java

@@ -0,0 +1,28 @@
+/*
+ * Copyright 2016 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.statemachine.data;
+
+import com.fasterxml.jackson.annotation.JsonTypeInfo;
+
+/**
+ * Generic base class for all entity classes.
+ *
+ * @author Janne Valkealahti
+ *
+ */
+@JsonTypeInfo(use=JsonTypeInfo.Id.CLASS, include=JsonTypeInfo.As.PROPERTY, property="_class")
+public abstract class BaseRepositoryEntity {
+}

spring-statemachine-data/src/main/java/org/springframework/statemachine/data/RepositoryState.java

@@ -18,59 +18,59 @@ package org.springframework.statemachine.data;
 import java.util.Set;
 
 /**
- * Generic interface representing state entity.
+ * Generic base class representing state entity.
  *
  * @author Janne Valkealahti
  *
  */
-public interface RepositoryState {
+public abstract class RepositoryState extends BaseRepositoryEntity {
 
 	/**
 	 * Gets the parent state.
 	 *
 	 * @return the parent state
 	 */
-	String getParentState();
+	public abstract String getParentState();
 
 	/**
 	 * Gets the machine id.
 	 *
 	 * @return the machine id
 	 */
-	String getMachineId();
+	public abstract String getMachineId();
 
 	/**
 	 * Gets the state.
 	 *
 	 * @return the state
 	 */
-	String getState();
+	public abstract String getState();
 
 	/**
 	 * Checks if is initial.
 	 *
 	 * @return true, if is initial
 	 */
-	boolean isInitial();
+	public abstract boolean isInitial();
 
 	/**
 	 * Gets the state actions.
 	 *
 	 * @return the state actions
 	 */
-	Set<? extends RepositoryAction> getStateActions();
+	public abstract Set<? extends RepositoryAction> getStateActions();
 
 	/**
 	 * Gets the entry actions.
 	 *
 	 * @return the entry actions
 	 */
-	Set<? extends RepositoryAction> getEntryActions();
+	public abstract Set<? extends RepositoryAction> getEntryActions();
 
 	/**
 	 * Gets the exit actions.
 	 *
 	 * @return the exit actions
 	 */
-	Set<? extends RepositoryAction> getExitActions();
+	public abstract Set<? extends RepositoryAction> getExitActions();
 }

spring-statemachine-data/src/main/java/org/springframework/statemachine/data/RepositoryStateMachineModelFactory.java

@@ -175,8 +175,7 @@ public class RepositoryStateMachineModelFactory extends AbstractStateMachineMode
 					guard = new SpelExpressionGuard<>(parser.parseExpression(repositoryGuard.getSpel()));
 				}
 			}
-
-			transitionData.add(new TransitionData<>(t.getSource(), t.getTarget(), t.getEvent(), actions, guard, kind != null ? kind : TransitionKind.EXTERNAL));
+			transitionData.add(new TransitionData<>(t.getSource().getState(), t.getTarget().getState(), t.getEvent(), actions, guard, kind != null ? kind : TransitionKind.EXTERNAL));
 		}
 		TransitionsData<String, String> transitionsData = new TransitionsData<>(transitionData);
 

spring-statemachine-data/src/main/java/org/springframework/statemachine/data/RepositoryTransition.java

@@ -20,59 +20,59 @@ import java.util.Set;
 import org.springframework.statemachine.transition.TransitionKind;
 
 /**
- * Generic interface representing transition entity.
+ * Generic base class representing transition entity.
  *
  * @author Janne Valkealahti
  *
  */
-public interface RepositoryTransition {
+public abstract class RepositoryTransition extends BaseRepositoryEntity {
 
 	/**
 	 * Gets the machine id.
 	 *
 	 * @return the machine id
 	 */
-	String getMachineId();
+	public abstract String getMachineId();
 
 	/**
 	 * Gets the source.
 	 *
 	 * @return the source
 	 */
-	String getSource();
+	public abstract RepositoryState getSource();
 
 	/**
 	 * Gets the target.
 	 *
 	 * @return the target
 	 */
-	String getTarget();
+	public abstract RepositoryState getTarget();
 
 	/**
 	 * Gets the event.
 	 *
 	 * @return the event
 	 */
-	String getEvent();
+	public abstract String getEvent();
 
 	/**
 	 * Gets the actions.
 	 *
 	 * @return the actions
 	 */
-	Set<? extends RepositoryAction> getActions();
+	public abstract Set<? extends RepositoryAction> getActions();
 
 	/**
 	 * Gets the guard.
 	 *
 	 * @return the guard
 	 */
-	RepositoryGuard getGuard();
+	public abstract RepositoryGuard getGuard();
 
 	/**
 	 * Gets the transition kind.
 	 *
 	 * @return the transition kind
 	 */
-	TransitionKind getKind();
+	public abstract TransitionKind getKind();
 }

spring-statemachine-data/src/main/java/org/springframework/statemachine/data/support/StateMachineJackson2RepositoryPopulatorFactoryBean.java

@@ -0,0 +1,48 @@
+/*
+ * Copyright 2016 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.statemachine.data.support;
+
+import org.springframework.beans.factory.FactoryBean;
+import org.springframework.data.repository.init.AbstractRepositoryPopulatorFactoryBean;
+import org.springframework.data.repository.init.ResourceReader;
+import org.springframework.data.repository.init.ResourceReaderRepositoryPopulator;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+/**
+ * {@link FactoryBean} to set up a {@link ResourceReaderRepositoryPopulator} with a {@link StateMachineJackson2ResourceReader}.
+ *
+ * @author Oliver Gierke
+ * @author Janne Valkealahti
+ */
+public class StateMachineJackson2RepositoryPopulatorFactoryBean extends AbstractRepositoryPopulatorFactoryBean {
+
+	private ObjectMapper mapper;
+
+	/**
+	 * Configures the {@link ObjectMapper} to be used.
+	 *
+	 * @param mapper the new mapper
+	 */
+	public void setMapper(ObjectMapper mapper) {
+		this.mapper = mapper;
+	}
+
+	@Override
+	protected ResourceReader getResourceReader() {
+		return new StateMachineJackson2ResourceReader(mapper);
+	}
+}

spring-statemachine-data/src/main/java/org/springframework/statemachine/data/support/StateMachineJackson2ResourceReader.java

@@ -0,0 +1,119 @@
+/*
+ * Copyright 2016 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.statemachine.data.support;
+
+import static com.fasterxml.jackson.databind.DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+import org.springframework.core.io.Resource;
+import org.springframework.data.repository.init.Jackson2ResourceReader;
+import org.springframework.data.repository.init.ResourceReader;
+import org.springframework.statemachine.data.BaseRepositoryEntity;
+import org.springframework.util.ClassUtils;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.ObjectReader;
+
+/**
+ * A {@link ResourceReader} using Jackson to read JSON into objects.
+ *
+ * @author Oliver Gierke
+ * @author Janne Valkealahti
+ */
+public class StateMachineJackson2ResourceReader implements ResourceReader {
+
+	/** The Constant DEFAULT_TYPE_KEY. */
+	private static final String DEFAULT_TYPE_KEY = "_class";
+
+	/** The Constant DEFAULT_MAPPER. */
+	private static final ObjectMapper DEFAULT_MAPPER = new ObjectMapper();
+
+	static {
+		DEFAULT_MAPPER.configure(FAIL_ON_UNKNOWN_PROPERTIES, false);
+	}
+
+	/** The mapper. */
+	private final ObjectMapper mapper;
+
+	/** The type key. */
+	private String typeKey = DEFAULT_TYPE_KEY;
+
+	/**
+	 * Creates a new {@link Jackson2ResourceReader}.
+	 */
+	public StateMachineJackson2ResourceReader() {
+		this(DEFAULT_MAPPER);
+	}
+
+	/**
+	 * Creates a new {@link Jackson2ResourceReader} using the given {@link ObjectMapper}.
+	 *
+	 * @param mapper the mapper
+	 */
+	public StateMachineJackson2ResourceReader(ObjectMapper mapper) {
+		this.mapper = mapper == null ? DEFAULT_MAPPER : mapper;
+	}
+
+	/**
+	 * Configures the JSON document's key to lookup the type to instantiate the object. Defaults to
+	 * {@link Jackson2ResourceReader#DEFAULT_TYPE_KEY}.
+	 *
+	 * @param typeKey the new type key
+	 */
+	public void setTypeKey(String typeKey) {
+		this.typeKey = typeKey;
+	}
+
+	@Override
+	public Object readFrom(Resource resource, ClassLoader classLoader) throws Exception {
+		InputStream stream = resource.getInputStream();
+		ObjectReader objectReader = mapper.readerFor(JsonNode.class);
+		JsonNode node = objectReader.readTree(stream);
+		objectReader = mapper.readerFor(BaseRepositoryEntity[].class);
+
+		if (node.isArray()) {
+			List<Object> result = new ArrayList<Object>();
+			BaseRepositoryEntity[] entitys = objectReader.readValue(node);
+			result.addAll(Arrays.asList(entitys));
+			return result;
+		}
+
+		return readSingle(node, classLoader);
+	}
+
+	/**
+	 * Reads the given {@link JsonNode} into an instance of the type encoded in it using the configured type key.
+	 *
+	 * @param node must not be {@literal null}.
+	 * @param classLoader the class loader
+	 * @return the object
+	 * @throws IOException Signals that an I/O exception has occurred.
+	 */
+	private Object readSingle(JsonNode node, ClassLoader classLoader) throws IOException {
+
+		JsonNode typeNode = node.findValue(typeKey);
+		String typeName = typeNode == null ? null : typeNode.asText();
+
+		Class<?> type = ClassUtils.resolveClassName(typeName, classLoader);
+		return mapper.readerFor(type).readValue(node);
+	}
+}