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WebDAV server implementations for JCR
/*
* 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.jackrabbit.server.remoting.davex;
import javax.jcr.Node;
import javax.jcr.NodeIterator;
import javax.jcr.Property;
import javax.jcr.PropertyIterator;
import javax.jcr.PropertyType;
import javax.jcr.RepositoryException;
import javax.jcr.Value;
import java.io.Writer;
import java.io.IOException;
import org.apache.jackrabbit.JcrConstants;
import org.apache.jackrabbit.commons.json.JsonUtil;
/**
* JsonWriter traverses a tree of JCR items and writes a JSON object
* exposing nodes as JSON object members and properties as JSON pairs.
*
* Note: Using JSON.org library is deliberately avoided for the
* following reasons.
*
* - JSONObject does not preserve the order of members added, which is required
* for JCR remoting.
* - JSONObject#numberToString:
* Double numbers get their trailing '.0' stripped away, which removes
* the ability to distinguish between JCR values of type {@link PropertyType#DOUBLE}
* and {@link PropertyType#LONG}.
*
*/
class JsonWriter {
private final Writer writer;
/**
* Create a new JsonItemWriter
*
* @param writer Writer to which the generated JSON string is written.
*/
JsonWriter(Writer writer) {
this.writer = writer;
}
/**
*
* @param node
* @param maxLevels
* @throws RepositoryException
* @throws IOException
*/
void write(Node node, int maxLevels) throws RepositoryException, IOException {
write(node, 0, maxLevels);
}
private void write(Node node, int currentLevel, int maxLevels)
throws RepositoryException, IOException {
// start of node info
writer.write('{');
// append the jcr properties as JSON pairs.
PropertyIterator props = node.getProperties();
while (props.hasNext()) {
Property prop = props.nextProperty();
writeProperty(writer, prop);
// add separator: next json pair/member is either a property or
// a childnode or the special no-children-present pair.
writer.write(',');
}
// for jcr child nodes include member unless the max-depths is reached.
// in case there are no children at all, append a special pair.
final NodeIterator children = node.getNodes();
if (!children.hasNext()) {
// no child present at all -> add special property.
writeKeyValue(writer, "::NodeIteratorSize", 0);
} else {
// the child nodes
while (children.hasNext()) {
final Node n = children.nextNode();
String name = n.getName();
int index = n.getIndex();
if (index > 1) {
writeKey(writer, name + "[" + index + "]");
} else {
writeKey(writer, name);
}
if (maxLevels < 0 || currentLevel < maxLevels) {
write(n, currentLevel + 1, maxLevels);
} else {
/**
* In order to be able to compute the set of child-node entries
* upon Node creation -> add incomplete "node info" JSON
* object for the child node omitting properties and child
* information except for the jcr:uuid property (if present
* at all).
* the latter is required in order to build the correct SPI
* ChildInfo for Node n.
*/
writeChildInfo(writer, n);
}
if (children.hasNext()) {
writer.write(',');
}
}
}
// end of node info
writer.write('}');
}
/**
* Write child info without including the complete node info.
*
* @param w
* @param n
* @throws RepositoryException
* @throws IOException
*/
private static void writeChildInfo(Writer w, Node n) throws RepositoryException, IOException {
// start child info
w.write('{');
// make sure the SPI childInfo can be built correctly on the
// client side -> pass uuid if present.
if (n.isNodeType(JcrConstants.MIX_REFERENCEABLE) &&
n.hasProperty(JcrConstants.JCR_UUID)) {
writeProperty(w, n.getProperty(JcrConstants.JCR_UUID));
}
// end child info
w.write('}');
}
/**
* Write a single property
*
* @param w
* @param p
* @throws javax.jcr.RepositoryException
* @throws java.io.IOException
*/
private static void writeProperty(Writer w, Property p) throws RepositoryException, IOException {
// special handling for binaries: we dump the length and not the length
int type = p.getType();
if (type == PropertyType.BINARY) {
// mark binary properties with a leading ':'
// the value(s) reflect the jcr-values length instead of the binary data.
String key = ":" + p.getName();
if (p.isMultiple()) {
long[] binLengths = p.getLengths();
writeKeyArray(w, key, binLengths);
} else {
writeKeyValue(w, key, p.getLength());
}
} else {
boolean isMultiple = p.isMultiple();
if (requiresTypeInfo(type) || (isMultiple && p.getValues().length == 0)) {
/* special property types that have no correspondence in JSON
are transported as String. the type is transported with an
extra key-value pair, the key having a leading ':' the value
reflects the type.
the same applies for multivalued properties consisting of an
empty array -> property type guessing would not be possible.
*/
writeKeyValue(w, ":" + p.getName(), PropertyType.nameFromValue(type), true);
}
/* append key-value pair containing the jcr value(s).
for String, Boolean, Double, Long -> types in json available */
if (isMultiple) {
writeKeyArray(w, p.getName(), p.getValues());
} else {
writeKeyValue(w, p.getName(), p.getValue());
}
}
}
private static boolean requiresTypeInfo(int type) {
switch (type) {
case PropertyType.NAME:
case PropertyType.PATH:
case PropertyType.REFERENCE:
case PropertyType.DATE:
case PropertyType.WEAKREFERENCE:
case PropertyType.URI:
case PropertyType.DECIMAL:
return true;
default:
// any other property type
return false;
}
}
private static void writeKeyValue(Writer w, String key, String value, boolean hasNext) throws IOException {
writeKey(w, key);
w.write(JsonUtil.getJsonString(value));
if (hasNext) {
w.write(',');
}
}
private static void writeKeyValue(Writer w, String key, Value value) throws RepositoryException, IOException {
writeKey(w, key);
w.write(getJsonValue(value));
}
private static void writeKeyArray(Writer w, String key, Value[] values) throws RepositoryException, IOException {
writeKey(w, key);
w.write('[');
for (int i = 0; i < values.length; i++) {
if (i > 0) {
w.write(',');
}
w.write(getJsonValue(values[i]));
}
w.write(']');
}
private static void writeKeyValue(Writer w, String key, long binLength) throws IOException {
writeKey(w, key);
w.write(binLength + "");
}
private static void writeKeyArray(Writer w, String key, long[] binLengths) throws RepositoryException, IOException {
writeKey(w, key);
w.write('[');
for (int i = 0; i < binLengths.length; i++) {
String delim = (i == 0) ? "" : ",";
w.write(delim + binLengths[i]);
}
w.write(']');
}
/**
*
* @param w
* @param key
* @throws IOException
*/
private static void writeKey(Writer w, String key) throws IOException {
w.write(JsonUtil.getJsonString(key));
w.write(':');
}
/**
* @param v
* @throws RepositoryException
* @throws IOException
*/
private static String getJsonValue(Value v) throws RepositoryException, IOException {
switch (v.getType()) {
case PropertyType.BINARY:
// should never get here
throw new IllegalArgumentException();
case PropertyType.BOOLEAN:
case PropertyType.LONG:
case PropertyType.DOUBLE:
return v.getString();
default:
return JsonUtil.getJsonString(v.getString());
}
}
}