org.apache.camel.component.xj.JsonXmlStreamReader Maven / Gradle / Ivy
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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.apache.camel.component.xj;
import java.io.IOException;
import java.io.UncheckedIOException;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Deque;
import java.util.List;
import java.util.stream.Collectors;
import javax.xml.namespace.NamespaceContext;
import javax.xml.namespace.QName;
import javax.xml.stream.Location;
import javax.xml.stream.XMLStreamConstants;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.core.JsonToken;
import org.apache.camel.util.ObjectHelper;
/**
* XML Json bridge. Explicitly using XMLStreamReader and not XMLEventReader because saxon wants that.
*/
public class JsonXmlStreamReader implements XMLStreamReader {
private static final String ERROR_MSG_NOT_IN_START_ELEMENT = "Current event is not start element";
private static final String ERROR_MSG_NOT_IN_START_END_ELEMENT = "Current event is not start element";
private static final String ERROR_MSG_NOT_IN_CHARACTERS = "Current event is not character";
private static final Location LOCATION = new Location() {
@Override
public int getLineNumber() {
return -1;
}
@Override
public int getColumnNumber() {
return -1;
}
@Override
public int getCharacterOffset() {
return -1;
}
@Override
public String getPublicId() {
return null;
}
@Override
public String getSystemId() {
return null;
}
};
private final JsonParser jsonParser;
private final Deque tokenStack = new ArrayDeque<>();
private boolean eof;
/**
* Creates a new JsonXmlStreamReader instance
*
* @param jsonParser the {@link JsonParser} to use to read the json document.
*/
public JsonXmlStreamReader(JsonParser jsonParser) {
this.jsonParser = jsonParser;
}
@Override
public Object getProperty(String name) throws IllegalArgumentException {
return null;
}
@Override
public int next() throws XMLStreamException {
try {
final StackElement previousElement = tokenStack.peek();
if (previousElement != null) {
switch (previousElement.jsonToken) {
case VALUE_STRING:
case VALUE_NUMBER_INT:
case VALUE_NUMBER_FLOAT:
case VALUE_NULL:
case VALUE_TRUE:
case VALUE_FALSE: {
switch (previousElement.xmlEvent) {
case XMLStreamConstants.START_ELEMENT:
previousElement.xmlEvent = XMLStreamConstants.CHARACTERS;
return XMLStreamConstants.CHARACTERS;
case XMLStreamConstants.CHARACTERS:
removeStackElement(previousElement.jsonToken);
removeStackElement(JsonToken.FIELD_NAME);
ObjectHelper.notNull(tokenStack.peek(), "tokenStack.peek()");
tokenStack.peek().xmlEvent = XMLStreamConstants.END_ELEMENT;
return XMLStreamConstants.END_ELEMENT;
default:
throw new IllegalStateException("illegal state");
}
}
default:
break;
}
}
if (eof) {
return END_DOCUMENT;
}
JsonToken currentToken = jsonParser.nextToken();
if (currentToken == null) {
throw new IllegalStateException("End of document");
}
StackElement stackElement = new StackElement(currentToken, toXmlString(jsonParser.getCurrentName()));
tokenStack.push(stackElement);
if (currentToken == JsonToken.FIELD_NAME) {
currentToken = jsonParser.nextToken();
stackElement = new StackElement(currentToken, toXmlString(jsonParser.getCurrentName()));
tokenStack.push(stackElement);
}
switch (currentToken) {
case START_OBJECT:
case START_ARRAY:
case VALUE_STRING:
case VALUE_NUMBER_INT:
case VALUE_NUMBER_FLOAT:
case VALUE_NULL:
case VALUE_TRUE:
case VALUE_FALSE:
stackElement.xmlEvent = XMLStreamConstants.START_ELEMENT;
return XMLStreamConstants.START_ELEMENT;
case END_OBJECT:
removeStackElement(JsonToken.END_OBJECT);
removeStackElement(JsonToken.START_OBJECT);
removeStackElement(JsonToken.FIELD_NAME);
eof = tokenStack.isEmpty();
return XMLStreamConstants.END_ELEMENT;
case END_ARRAY:
removeStackElement(JsonToken.END_ARRAY);
removeStackElement(JsonToken.START_ARRAY);
removeStackElement(JsonToken.FIELD_NAME);
eof = tokenStack.isEmpty();
return XMLStreamConstants.END_ELEMENT;
default:
throw new IllegalStateException("JsonToken: " + currentToken);
}
} catch (IOException e) {
throw new XMLStreamException(e);
}
}
private void removeStackElement(JsonToken jsonToken) {
final StackElement stackElement = tokenStack.peek();
if (stackElement == null || stackElement.jsonToken != jsonToken) {
if (stackElement != null && jsonToken == JsonToken.FIELD_NAME
&& stackElement.jsonToken == JsonToken.START_ARRAY) {
// anonymous array
return;
}
if (stackElement == null && jsonToken == JsonToken.FIELD_NAME) {
// root object / array
return;
}
final String stackElements = tokenStack.stream().map(StackElement::toString).collect(Collectors.joining("\n"));
throw new IllegalStateException(
"Stack element did not match expected (" + jsonToken + ") one. Stack:\n" + stackElements);
}
tokenStack.pop();
}
@Override
public void require(int type, String namespaceURI, String localName) {
throw new UnsupportedOperationException(XJConstants.UNSUPPORTED_OPERATION_EXCEPTION_MESSAGE);
}
@Override
public String getElementText() {
throw new UnsupportedOperationException(XJConstants.UNSUPPORTED_OPERATION_EXCEPTION_MESSAGE);
}
@Override
public int nextTag() throws XMLStreamException {
int evt;
do {
evt = next();
} while (evt != XMLStreamConstants.START_ELEMENT && evt != XMLStreamConstants.END_ELEMENT);
return evt;
}
@Override
public boolean hasNext() {
return !eof;
}
@Override
public void close() throws XMLStreamException {
try {
jsonParser.close();
} catch (IOException e) {
throw new XMLStreamException(e);
}
}
@Override
public String getNamespaceURI(String prefix) {
return null;
}
@Override
public boolean isStartElement() {
final StackElement stackElement = tokenStack.peek();
if (stackElement == null) {
return false;
}
return stackElement.xmlEvent == XMLStreamConstants.START_ELEMENT;
}
@Override
public boolean isEndElement() {
final StackElement stackElement = tokenStack.peek();
if (stackElement == null) {
return false;
}
return stackElement.xmlEvent == XMLStreamConstants.END_ELEMENT;
}
@Override
public boolean isCharacters() {
final StackElement stackElement = tokenStack.peek();
if (stackElement == null) {
return false;
}
return stackElement.xmlEvent == XMLStreamConstants.CHARACTERS;
}
@Override
public boolean isWhiteSpace() {
return false;
}
@Override
public String getAttributeValue(String namespaceURI, String localName) {
throw new UnsupportedOperationException(XJConstants.UNSUPPORTED_OPERATION_EXCEPTION_MESSAGE);
}
@Override
public int getAttributeCount() {
final StackElement stackElement = tokenStack.peek();
if (stackElement == null || stackElement.xmlEvent != XMLStreamConstants.START_ELEMENT) {
throw new IllegalStateException(ERROR_MSG_NOT_IN_START_ELEMENT);
}
return stackElement.getAttributeCount();
}
@Override
public QName getAttributeName(int index) {
final StackElement stackElement = tokenStack.peek();
if (stackElement == null || stackElement.xmlEvent != XMLStreamConstants.START_ELEMENT) {
throw new IllegalStateException(ERROR_MSG_NOT_IN_START_ELEMENT);
}
return stackElement.getAttribute(index);
}
@Override
public String getAttributeNamespace(int index) {
final StackElement stackElement = tokenStack.peek();
if (stackElement == null || stackElement.xmlEvent != XMLStreamConstants.START_ELEMENT) {
throw new IllegalStateException(ERROR_MSG_NOT_IN_START_ELEMENT);
}
return stackElement.getAttribute(index).getNamespaceURI();
}
@Override
public String getAttributeLocalName(int index) {
final StackElement stackElement = tokenStack.peek();
if (stackElement == null || stackElement.xmlEvent != XMLStreamConstants.START_ELEMENT) {
throw new IllegalStateException(ERROR_MSG_NOT_IN_START_ELEMENT);
}
return stackElement.getAttribute(index).getLocalPart();
}
@Override
public String getAttributePrefix(int index) {
final StackElement stackElement = tokenStack.peek();
if (stackElement == null || stackElement.xmlEvent != XMLStreamConstants.START_ELEMENT) {
throw new IllegalStateException(ERROR_MSG_NOT_IN_START_ELEMENT);
}
return stackElement.getAttribute(index).getPrefix();
}
@Override
public String getAttributeType(int index) {
final StackElement stackElement = tokenStack.peek();
if (stackElement == null || stackElement.xmlEvent != XMLStreamConstants.START_ELEMENT) {
throw new IllegalStateException(ERROR_MSG_NOT_IN_START_ELEMENT);
}
return "CDATA";
}
@Override
public String getAttributeValue(int index) {
final StackElement stackElement = tokenStack.peek();
if (stackElement == null || stackElement.xmlEvent != XMLStreamConstants.START_ELEMENT) {
throw new IllegalStateException(ERROR_MSG_NOT_IN_START_ELEMENT);
}
return tokenStack.peek().getAttributeValue(index);
}
@Override
public boolean isAttributeSpecified(int index) {
return false;
}
@Override
public int getNamespaceCount() {
// declare ns on root element
if (tokenStack.size() == 1) {
return 1;
}
return 0;
}
@Override
public String getNamespacePrefix(int index) {
final StackElement stackElement = tokenStack.peek();
if (stackElement == null || stackElement.xmlEvent != XMLStreamConstants.START_ELEMENT
&& stackElement.xmlEvent != XMLStreamConstants.END_ELEMENT) {
throw new IllegalStateException(ERROR_MSG_NOT_IN_START_END_ELEMENT);
}
return XJConstants.NS_PREFIX_XJ;
}
@Override
public String getNamespaceURI(int index) {
final StackElement stackElement = tokenStack.peek();
if (stackElement == null || stackElement.xmlEvent != XMLStreamConstants.START_ELEMENT
&& stackElement.xmlEvent != XMLStreamConstants.END_ELEMENT) {
throw new IllegalStateException(ERROR_MSG_NOT_IN_START_END_ELEMENT);
}
return XJConstants.NS_XJ;
}
@Override
public NamespaceContext getNamespaceContext() {
throw new UnsupportedOperationException(XJConstants.UNSUPPORTED_OPERATION_EXCEPTION_MESSAGE);
}
@Override
public int getEventType() {
if (eof) {
return XMLStreamConstants.END_DOCUMENT;
}
if (tokenStack.isEmpty()) {
return XMLStreamConstants.START_DOCUMENT;
}
return tokenStack.peek().xmlEvent;
}
@Override
public String getText() {
return new String(getTextCharacters());
}
@Override
public char[] getTextCharacters() {
final StackElement stackElement = tokenStack.peek();
if (stackElement == null || stackElement.xmlEvent != XMLStreamConstants.CHARACTERS) {
throw new IllegalStateException(ERROR_MSG_NOT_IN_CHARACTERS);
}
try {
setXmlText(stackElement, jsonParser);
return stackElement.value;
} catch (IOException e) {
throw new UncheckedIOException(e);
}
}
@Override
public int getTextCharacters(int sourceStart, char[] target, int targetStart, int length) {
final char[] text = getTextCharacters();
System.arraycopy(text, sourceStart, target, targetStart, length);
return sourceStart + length;
}
@Override
public int getTextStart() {
// always starts at 0 because we normalized the text in setXmlText();
return 0;
}
@Override
public int getTextLength() {
final StackElement stackElement = tokenStack.peek();
try {
ObjectHelper.notNull(stackElement, "stackElement");
setXmlText(stackElement, jsonParser);
return stackElement.value.length;
} catch (IOException e) {
throw new UncheckedIOException(e);
}
}
private void setXmlText(StackElement stackElement, JsonParser jsonParser) throws IOException {
if (stackElement.value == null) {
stackElement.value
= toXmlString(jsonParser.getTextCharacters(), jsonParser.getTextOffset(), jsonParser.getTextLength());
}
}
@Override
public String getEncoding() {
return null;
}
@Override
public boolean hasText() {
final StackElement stackElement = tokenStack.peek();
if (stackElement == null) {
return false;
}
return stackElement.xmlEvent == XMLStreamConstants.CHARACTERS;
}
@Override
public Location getLocation() {
return LOCATION;
}
@Override
public QName getName() {
return new QName("object");
}
@Override
public String getLocalName() {
return "object";
}
@Override
public boolean hasName() {
final StackElement stackElement = tokenStack.peek();
if (stackElement == null) {
return false;
}
return stackElement.xmlEvent == XMLStreamConstants.START_ELEMENT
|| stackElement.xmlEvent == XMLStreamConstants.END_ELEMENT;
}
@Override
public String getNamespaceURI() {
return null;
}
@Override
public String getPrefix() {
return null;
}
@Override
public String getVersion() {
return null;
}
@Override
public boolean isStandalone() {
return false;
}
@Override
public boolean standaloneSet() {
return false;
}
@Override
public String getCharacterEncodingScheme() {
return null;
}
@Override
public String getPITarget() {
return null;
}
@Override
public String getPIData() {
return null;
}
private String toXmlString(String input) {
if (input == null || input.isEmpty()) {
return null;
}
final char[] chars = input.toCharArray();
return new String(toXmlString(chars, 0, chars.length));
}
private char[] toXmlString(char[] input, int offset, int length) {
if (length == 0) {
return new char[0];
}
char[] res = new char[length];
int copied = 0;
for (int i = offset; i < (offset + length); i++) {
final char cur = input[i];
if (cur < 9 || cur > 10 && cur < 13 || cur > 13 && cur < 32) { // non valid xml characters
continue;
}
res[copied++] = cur;
}
return Arrays.copyOfRange(res, 0, copied);
}
/**
* Class that represents an element on the stack.
*/
private static class StackElement {
private final JsonToken jsonToken;
private final String name;
private final List attributes;
private int xmlEvent;
private char[] value;
StackElement(JsonToken jsonToken, String name) {
this.jsonToken = jsonToken;
this.name = name;
this.attributes = new ArrayList<>(2);
if (name != null) {
final QName nameAttribute = new QName(XJConstants.NS_XJ, XJConstants.TYPE_HINT_NAME, XJConstants.NS_PREFIX_XJ);
attributes.add(nameAttribute);
}
final QName typeAttribute = new QName(XJConstants.NS_XJ, XJConstants.TYPE_HINT_TYPE, XJConstants.NS_PREFIX_XJ);
attributes.add(typeAttribute);
}
int getAttributeCount() {
return attributes.size();
}
QName getAttribute(int idx) {
return attributes.get(idx);
}
String getAttributeValue(int idx) {
final QName attribute = getAttribute(idx);
switch (attribute.getLocalPart()) {
case XJConstants.TYPE_HINT_NAME:
return this.name;
case XJConstants.TYPE_HINT_TYPE:
return XJConstants.JSONTYPE_TYPE_MAP.get(this.jsonToken);
default:
throw new IllegalArgumentException("Unknown attribute " + attribute.getLocalPart());
}
}
@Override
public String toString() {
return "StackElement{"
+ "jsonToken=" + jsonToken
+ ", name='" + name + '\''
+ ", xmlEvent=" + xmlEvent
+ ", value=" + Arrays.toString(value)
+ ", attributes=" + attributes
+ '}';
}
}
}
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