JacksonJsonNodeSink.java
/*
* #%L
* wcm.io
* %%
* Copyright (C) 2014 wcm.io
* %%
* 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.
* #L%
*/
package io.wcm.caravan.io.jsontransform.sink;
import java.io.IOException;
import java.math.BigDecimal;
import java.util.Stack;
import org.osgi.annotation.versioning.ProviderType;
import com.fasterxml.jackson.core.JsonFactory;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.node.ArrayNode;
import com.fasterxml.jackson.databind.node.ObjectNode;
import io.wcm.caravan.io.jsontransform.element.JsonElement;
/**
* Converts the JSON stream elements into {@link JsonNode}s.
*/
@ProviderType
public final class JacksonJsonNodeSink implements Sink {
private final Stack<JsonNode> breadCrumb = new Stack<JsonNode>();
private final ObjectMapper mapper;
private JsonNode root;
/**
* @param factory JSON factory to initiate the Object Mapper.
*/
public JacksonJsonNodeSink(final JsonFactory factory) {
mapper = new ObjectMapper(factory);
}
/**
* @return The root node
*/
public JsonNode getJsonNode() {
return root;
}
@Override
public void close() throws IOException {
// nothing to do
}
@Override
public void write(JsonElement element) throws IOException {
switch (element.getType()) {
case START_OBJECT:
handleStartObject(element);
break;
case END_OBJECT:
breadCrumb.pop();
break;
case START_ARRAY:
handleStartArray(element);
break;
case END_ARRAY:
breadCrumb.pop();
break;
case VALUE:
handleValue(element);
break;
default:
// nothing to do
}
}
private void handleStartObject(final JsonElement element) {
if (isRootElement(element)) {
root = mapper.createObjectNode();
breadCrumb.add(root);
}
else if (isObjectProperty(element)) {
breadCrumb.add(getCurrentObjectNode().putObject(element.getKey()));
}
else if (isArrayChild(element)) {
breadCrumb.add(getCurrentArrayNode().addObject());
}
}
private boolean isRootElement(final JsonElement element) {
return breadCrumb.isEmpty() && element.getKey() == null;
}
private boolean isObjectProperty(final JsonElement element) {
return breadCrumb.peek() instanceof ObjectNode && element.getKey() != null;
}
private boolean isArrayChild(final JsonElement element) {
return breadCrumb.peek() instanceof ArrayNode;
}
private ObjectNode getCurrentObjectNode() {
return (ObjectNode)breadCrumb.peek();
}
private ArrayNode getCurrentArrayNode() {
return (ArrayNode)breadCrumb.peek();
}
private void handleStartArray(final JsonElement element) {
if (isRootElement(element)) {
root = mapper.createArrayNode();
breadCrumb.add(root);
}
else if (isObjectProperty(element)) {
breadCrumb.add(getCurrentObjectNode().putArray(element.getKey()));
}
else if (isArrayChild(element)) {
breadCrumb.add(getCurrentArrayNode().addArray());
}
}
private void handleValue(final JsonElement element) {
if (isObjectProperty(element)) {
if (element.getValue() instanceof BigDecimal) {
getCurrentObjectNode().put(element.getKey(), (BigDecimal)element.getValue());
}
else if (element.getValue() instanceof Boolean) {
getCurrentObjectNode().put(element.getKey(), (Boolean)element.getValue());
}
else {
getCurrentObjectNode().put(element.getKey(), (String)element.getValue());
}
}
else if (isArrayChild(element)) {
if (element.getValue() instanceof BigDecimal) {
getCurrentArrayNode().add((BigDecimal)element.getValue());
}
else if (element.getValue() instanceof Boolean) {
getCurrentArrayNode().add((Boolean)element.getValue());
}
else {
getCurrentArrayNode().add((String)element.getValue());
}
}
}
@Override
public boolean hasOutput() {
return root != null;
}
}