com.sun.jersey.json.impl.reader.XmlEventProvider Maven / Gradle / Ivy
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package com.sun.jersey.json.impl.reader;
import java.io.IOException;
import java.util.Deque;
import java.util.LinkedList;
import java.util.Queue;
import java.util.Stack;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.xml.namespace.QName;
import javax.xml.stream.Location;
import javax.xml.stream.XMLStreamException;
import com.sun.jersey.api.json.JSONConfiguration;
import org.codehaus.jackson.JsonLocation;
import org.codehaus.jackson.JsonParser;
import org.codehaus.jackson.JsonToken;
/**
* Abstract provider for creating {@code JsonXmlEvent} instances from {@code JsonParser}. Extensions of this class should
* adjust their behaviour according to the JSON notation they are supporting.
*
* @author Michal Gajdos (michal.gajdos at oracle.com)
*/
public abstract class XmlEventProvider {
private static class ProcessingInfo {
QName name;
boolean isArray;
boolean isFirstElement;
ProcessingInfo(QName name, boolean isArray, boolean isFirstElement) {
this.name = name;
this.isArray = isArray;
this.isFirstElement = isFirstElement;
}
}
/**
* This wrapper of the {@code JsonParser} allows to peek at the following tokens without actually processing them.
*/
private static class CachedJsonParser {
/**
* JSON parser.
*/
private final JsonParser parser;
private final Queue tokens = new LinkedList();
public CachedJsonParser(final JsonParser parser) {
this.parser = parser;
}
public JsonToken nextToken() throws IOException {
return tokens.isEmpty() ? parser.nextToken() : tokens.poll();
}
public JsonToken peekNext() throws IOException {
final JsonToken jsonToken = parser.nextToken();
tokens.add(jsonToken);
return jsonToken;
}
public JsonToken peek() throws IOException {
if (tokens.isEmpty()) {
tokens.add(parser.nextToken());
}
return tokens.peek();
}
public JsonToken poll() throws IOException {
return tokens.poll();
}
public void close() throws IOException {
parser.close();
}
public JsonLocation getCurrentLocation() {
return parser.getCurrentLocation();
}
public String getText() throws IOException {
return parser.getText();
}
public String getCurrentName() throws IOException {
return parser.getCurrentName();
}
public boolean hasMoreTokens() throws IOException {
try {
return peek() != null;
} catch (IOException e) {
return false;
}
}
}
private static final Logger LOGGER = Logger.getLogger(XmlEventProvider.class.getName());
private final JSONConfiguration configuration;
/**
* JSON parser.
*/
private final CachedJsonParser parser;
private final String rootName;
/**
* Queue of unprocessed events.
*/
private final Deque eventQueue = new LinkedList();
private final Stack processingStack = new Stack();
protected XmlEventProvider(final JsonParser parser, final JSONConfiguration configuration, final String rootName)
throws XMLStreamException {
this.parser = new CachedJsonParser(parser);
this.configuration = configuration;
this.rootName = rootName;
try {
readNext();
} catch (XMLStreamException ex) {
LOGGER.log(Level.SEVERE, ex.getMessage(), ex);
throw new XMLStreamException(ex);
}
}
/**
* @see com.sun.jersey.json.impl.reader.JsonXmlStreamReader#close()
*/
void close() throws XMLStreamException {
eventQueue.clear();
processingStack.empty();
try {
parser.close();
} catch (IOException ioe) {
throw new XMLStreamException(ioe);
}
}
/**
* Creates an {@code EndElementEvent}.
*
* @param elementName name of element for which the end element should be created.
* @param location location of this end element in the JSON stream.
* @return end element event.
*/
protected JsonXmlEvent createEndElementEvent(final QName elementName, final Location location) {
return new EndElementEvent(elementName, location);
}
/**
* Creates an {@code StartElementEvent}.
*
* @param elementName name of element for which the start element should be created.
* @param location location of this start element in the JSON stream.
* @return start element event.
*/
protected JsonXmlEvent createStartElementEvent(final QName elementName, final Location location) {
return new StartElementEvent(elementName, location);
}
/**
* Returns the name of an attribute from the given field name without the leading '@' character if present.
*
* @param jsonFieldName field name representing the attribute name.
* @return the name of an attribute.
*/
protected String getAttributeName(final String jsonFieldName) {
return '@' == jsonFieldName.charAt(0) ? jsonFieldName.substring(1) : jsonFieldName;
}
/**
* Returns the attribute qualified name which is determined from the given {@code jsonFieldName} and configuration of the
* underlying implementation.
*
* @param jsonFieldName name of the json field to obtain the qualified name for.
* @return qualified name of the attribute.
*/
protected abstract QName getAttributeQName(final String jsonFieldName);
JsonXmlEvent getCurrentNode() {
return eventQueue.peek();
}
/**
* Returns the element qualified name which is determined from the given {@code jsonFieldName} and configuration of the
* underlying implementation.
*
* @param jsonFieldName name of the json field to obtain the qualified name for.
* @return qualified name of the element.
*/
protected abstract QName getElementQName(final String jsonFieldName);
protected JSONConfiguration getJsonConfiguration() {
return configuration;
}
/**
* Checks whether the {@code jsonToken} belongs to the group of primitive json values (not an object or an array) and returns
* the given {@code jsonFieldValue} if the conditions are met. If the {@code jsonFieldValue} does not represents primitive
* json value an {@code IOException} is thrown.
*
* @param jsonToken token to determine whether the given value is of simple json type.
* @param jsonFieldValue value to be returned if it's one of the simple json types.
* @return simple json type value.
* @throws IOException if the given value doesn't belong to the group of primitive json values.
*/
private String getPrimitiveFieldValue(final JsonToken jsonToken, final String jsonFieldValue) throws IOException {
if (jsonToken == JsonToken.VALUE_FALSE
|| jsonToken == JsonToken.VALUE_TRUE
|| jsonToken == JsonToken.VALUE_STRING
|| jsonToken == JsonToken.VALUE_NUMBER_FLOAT
|| jsonToken == JsonToken.VALUE_NUMBER_INT
|| jsonToken == JsonToken.VALUE_NULL) {
return jsonFieldValue;
}
throw new IOException("Not an XML value, expected primitive value!");
}
/**
* Determines whether the given json field name represents an attribute name.
*
* @param jsonFieldName json field name to be examined.
* @return {@code true} if the given name represents an attribute, {@code false} otherwise.
*/
protected abstract boolean isAttribute(final String jsonFieldName);
/**
* Retrieves and sets attributes for the current element from JSON stream.
*
* @throws XMLStreamException if an error occurred during the processing of the JSON stream.
* @see #processTokens(boolean)
*/
void processAttributesOfCurrentElement() throws XMLStreamException {
eventQueue.peek().setAttributes(new LinkedList());
processTokens(true);
}
private JsonXmlEvent processTokens(boolean processAttributes) throws XMLStreamException {
if (!processAttributes) {
// get rid of the current event
eventQueue.poll();
}
try {
while (eventQueue.isEmpty() || processAttributes) {
while (true) {
final JsonToken jsonToken = parser.nextToken();
final ProcessingInfo pi = processingStack.isEmpty() ? null : processingStack.peek();
if (jsonToken == null) {
return getCurrentNode();
}
switch (jsonToken) {
case FIELD_NAME:
final String fieldName = parser.getCurrentName();
if (isAttribute(fieldName)) {
// attribute
final QName attributeName = getAttributeQName(fieldName);
final String attributeValue = getPrimitiveFieldValue(parser.nextToken(), parser.getText());
eventQueue.peek().getAttributes().add(new JsonXmlEvent.Attribute(attributeName, attributeValue));
} else {
processAttributes = false;
// child event
if ("$".equals(fieldName)) {
// character event
final String value = getPrimitiveFieldValue(parser.nextToken(), parser.getText());
eventQueue.add(new CharactersEvent(value, new StaxLocation(parser.getCurrentLocation())));
} else {
// element event
final QName elementName = getElementQName(fieldName);
final JsonLocation currentLocation = parser.getCurrentLocation();
final boolean isRootEmpty = isEmptyElement(fieldName, true);
if (isRootEmpty) {
eventQueue.add(createStartElementEvent(elementName, new StaxLocation(currentLocation)));
eventQueue.add(createEndElementEvent(elementName, new StaxLocation(currentLocation)));
eventQueue.add(new EndDocumentEvent(new StaxLocation(parser.getCurrentLocation())));
} else {
if (!isEmptyArray() && !isEmptyElement(fieldName, false)) {
eventQueue.add(createStartElementEvent(elementName, new StaxLocation(currentLocation)));
processingStack.add(new ProcessingInfo(elementName, false, true));
}
if (!parser.hasMoreTokens()) {
eventQueue.add(new EndDocumentEvent(new StaxLocation(parser.getCurrentLocation())));
}
}
if (eventQueue.isEmpty()) {
continue;
}
return getCurrentNode();
}
}
break;
case START_OBJECT:
if (pi == null) {
eventQueue.add(new StartDocumentEvent(new StaxLocation(0, 0, 0)));
return getCurrentNode();
}
if (pi.isArray && !pi.isFirstElement) {
eventQueue.add(createStartElementEvent(pi.name, new StaxLocation(parser.getCurrentLocation())));
return getCurrentNode();
} else {
pi.isFirstElement = false;
}
break;
case END_OBJECT:
processAttributes = false;
// end tag
eventQueue.add(createEndElementEvent(pi.name, new StaxLocation(parser.getCurrentLocation())));
if (!pi.isArray) {
processingStack.pop();
}
if (processingStack.isEmpty()) {
eventQueue.add(new EndDocumentEvent(new StaxLocation(parser.getCurrentLocation())));
// Eat the last '}' and check whether there is another (unexpected) token.
final JsonToken nextToken = parser.nextToken();
if ((nextToken != null && nextToken != JsonToken.END_OBJECT)
|| parser.peek() != null) {
throw new RuntimeException("Unexpected token: " + parser.getText());
}
}
return getCurrentNode();
case VALUE_FALSE:
case VALUE_NULL:
case VALUE_NUMBER_FLOAT:
case VALUE_NUMBER_INT:
case VALUE_TRUE:
case VALUE_STRING:
if (!pi.isFirstElement) {
eventQueue.add(createStartElementEvent(pi.name, new StaxLocation(parser.getCurrentLocation())));
} else {
pi.isFirstElement = false;
}
if (jsonToken != JsonToken.VALUE_NULL) {
eventQueue.add(new CharactersEvent(parser.getText(), new StaxLocation(parser.getCurrentLocation())));
}
eventQueue.add(new EndElementEvent(pi.name, new StaxLocation(parser.getCurrentLocation())));
if (!pi.isArray) {
processingStack.pop();
}
if (processingStack.isEmpty()) {
eventQueue.add(new EndDocumentEvent(new StaxLocation(parser.getCurrentLocation())));
}
processAttributes = false;
return getCurrentNode();
case START_ARRAY:
processingStack.peek().isArray = true;
break;
case END_ARRAY:
processingStack.pop();
processAttributes = false;
break;
default:
throw new IllegalStateException("Unknown JSON token: " + jsonToken);
}
}
}
return eventQueue.peek();
} catch (Exception e) {
throw new XMLStreamException(e);
}
}
/**
* Checks if the currently processed JSON field is represented as an empty array. If so array tokens are thrown away and no
* {@code StartElementEvent} should be created.
*
* @return {@code true} if next tokens signalize an empty array, {@code false} otherwise.
* @throws IOException if there is a problem reading next {@code JsonToken}.
*/
private boolean isEmptyArray() throws IOException {
final JsonToken jsonToken = parser.peek();
if (jsonToken == JsonToken.START_ARRAY && parser.peekNext() == JsonToken.END_ARRAY) {
// throw away parser tokens
parser.poll();
parser.poll();
return true;
}
return false;
}
private boolean isEmptyElement(final String fieldName, boolean checkRoot) throws IOException {
if (!checkRoot || (fieldName != null && fieldName.equals(rootName))) {
final JsonToken jsonToken = parser.peek();
if (jsonToken == JsonToken.VALUE_NULL) {
parser.poll();
if (parser.peek() == JsonToken.END_OBJECT) {
// in case jsonToken == JsonToken.VALUE_NULL - check if the next token is '}'
parser.poll();
}
return true;
}
}
return false;
}
/**
* Reads and returns next {@code JsonXmlEvent}.
*
* @return an instance of {@code JsonXmlEvent}.
* @throws XMLStreamException if something went wrong.
*/
JsonXmlEvent readNext() throws XMLStreamException {
return processTokens(false);
}
}
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