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java.util.prefs.XMLParser Maven / Gradle / Ivy
/* 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 java.util.prefs;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.Reader;
import java.io.StringReader;
import java.util.ArrayList;
import java.util.Properties;
import java.util.StringTokenizer;
import java.util.UUID;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.FactoryConfigurationError;
import javax.xml.parsers.ParserConfigurationException;
import libcore.io.IoUtils;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.EntityResolver;
import org.xml.sax.ErrorHandler;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
/**
* Utility class for the Preferences import/export from XML file.
*/
class XMLParser {
/*
* Constant - the specified DTD URL
*/
static final String PREFS_DTD_NAME = "http://java.sun.com/dtd/preferences.dtd";
/*
* Constant - the DTD string
*/
static final String PREFS_DTD = ""
+ " "
+ " "
+ " "
+ " "
+ " "
+ " "
+ " "
+ " "
+ " ";
/*
* Constant - the specified header
*/
static final String HEADER = "";
/*
* Constant - the specified DOCTYPE
*/
static final String DOCTYPE = "";
/*
* Constant - specify the DTD version
*/
private static final float XML_VERSION = 1.0f;
/*
* DOM builder
*/
private static final DocumentBuilder builder;
/*
* specify the indent level
*/
private static int indent = -1;
/*
* init DOM builder
*/
static {
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
factory.setValidating(false);
try {
builder = factory.newDocumentBuilder();
} catch (ParserConfigurationException e) {
throw new Error(e);
}
builder.setEntityResolver(new EntityResolver() {
public InputSource resolveEntity(String publicId, String systemId)
throws SAXException, IOException {
if (systemId.equals(PREFS_DTD_NAME)) {
InputSource result = new InputSource(new StringReader(
PREFS_DTD));
result.setSystemId(PREFS_DTD_NAME);
return result;
}
throw new SAXException("Invalid DOCTYPE declaration " + systemId);
}
});
builder.setErrorHandler(new ErrorHandler() {
public void warning(SAXParseException e) throws SAXException {
throw e;
}
public void error(SAXParseException e) throws SAXException {
throw e;
}
public void fatalError(SAXParseException e) throws SAXException {
throw e;
}
});
}
private XMLParser() {// empty constructor
}
/***************************************************************************
* utilities for Preferences export
**************************************************************************/
static void exportPrefs(Preferences prefs, OutputStream stream,
boolean withSubTree) throws IOException, BackingStoreException {
indent = -1;
BufferedWriter out = new BufferedWriter(new OutputStreamWriter(stream, "UTF-8"));
out.write(HEADER);
out.newLine();
out.newLine();
out.write(DOCTYPE);
out.write(" '");
out.write(PREFS_DTD_NAME);
out.write("'>");
out.newLine();
out.newLine();
flushStartTag("preferences", new String[] { "EXTERNAL_XML_VERSION" },
new String[] { String.valueOf(XML_VERSION) }, out);
flushStartTag("root", new String[] { "type" },
new String[] { prefs.isUserNode() ? "user" : "system" }, out);
flushEmptyElement("map", out);
StringTokenizer ancestors = new StringTokenizer(prefs.absolutePath(), "/");
exportNode(ancestors, prefs, withSubTree, out);
flushEndTag("root", out);
flushEndTag("preferences", out);
out.flush();
out = null;
}
private static void exportNode(StringTokenizer ancestors,
Preferences prefs, boolean withSubTree, BufferedWriter out)
throws IOException, BackingStoreException {
if (ancestors.hasMoreTokens()) {
String name = ancestors.nextToken();
flushStartTag("node", new String[] { "name" }, new String[] { name }, out);
if (ancestors.hasMoreTokens()) {
flushEmptyElement("map", out);
exportNode(ancestors, prefs, withSubTree, out);
} else {
exportEntries(prefs, out);
if (withSubTree) {
exportSubTree(prefs, out);
}
}
flushEndTag("node", out);
}
}
private static void exportSubTree(Preferences prefs, BufferedWriter out)
throws BackingStoreException, IOException {
String[] names = prefs.childrenNames();
if (names.length > 0) {
for (int i = 0; i < names.length; i++) {
Preferences child = prefs.node(names[i]);
flushStartTag("node", new String[] { "name" }, new String[] { names[i] }, out);
exportEntries(child, out);
exportSubTree(child, out);
flushEndTag("node", out);
}
}
}
private static void exportEntries(Preferences prefs, BufferedWriter out)
throws BackingStoreException, IOException {
String[] keys = prefs.keys();
String[] values = new String[keys.length];
for (int i = 0; i < keys.length; i++) {
values[i] = prefs.get(keys[i], null);
}
exportEntries(keys, values, out);
}
private static void exportEntries(String[] keys, String[] values,
BufferedWriter out) throws IOException {
if (keys.length == 0) {
flushEmptyElement("map", out);
return;
}
flushStartTag("map", out);
for (int i = 0; i < keys.length; i++) {
if (values[i] != null) {
flushEmptyElement("entry", new String[] { "key", "value" },
new String[] { keys[i], values[i] }, out);
}
}
flushEndTag("map", out);
}
private static void flushEndTag(String tagName, BufferedWriter out)
throws IOException {
flushIndent(indent--, out);
out.write("");
out.newLine();
}
private static void flushEmptyElement(String tagName, BufferedWriter out)
throws IOException {
flushIndent(++indent, out);
out.write("<");
out.write(tagName);
out.write(" />");
out.newLine();
indent--;
}
private static void flushEmptyElement(String tagName, String[] attrKeys,
String[] attrValues, BufferedWriter out) throws IOException {
flushIndent(++indent, out);
out.write("<");
out.write(tagName);
flushPairs(attrKeys, attrValues, out);
out.write(" />");
out.newLine();
indent--;
}
private static void flushPairs(String[] attrKeys, String[] attrValues,
BufferedWriter out) throws IOException {
for (int i = 0; i < attrKeys.length; i++) {
out.write(" ");
out.write(attrKeys[i]);
out.write("=\"");
out.write(htmlEncode(attrValues[i]));
out.write("\"");
}
}
private static void flushIndent(int ind, BufferedWriter out)
throws IOException {
for (int i = 0; i < ind; i++) {
out.write(" ");
}
}
private static void flushStartTag(String tagName, String[] attrKeys,
String[] attrValues, BufferedWriter out) throws IOException {
flushIndent(++indent, out);
out.write("<");
out.write(tagName);
flushPairs(attrKeys, attrValues, out);
out.write(">");
out.newLine();
}
private static void flushStartTag(String tagName, BufferedWriter out)
throws IOException {
flushIndent(++indent, out);
out.write("<");
out.write(tagName);
out.write(">");
out.newLine();
}
private static String htmlEncode(String s) {
StringBuilder sb = new StringBuilder();
for (int i = 0; i < s.length(); i++) {
char c = s.charAt(i);
switch (c) {
case '<':
sb.append("<");
break;
case '>':
sb.append(">");
break;
case '&':
sb.append("&");
break;
case '"':
sb.append(""");
break;
default:
sb.append(c);
}
}
return sb.toString();
}
/***************************************************************************
* utilities for Preferences import
**************************************************************************/
static void importPrefs(InputStream in) throws IOException, InvalidPreferencesFormatException {
try {
// load XML document
Document doc = builder.parse(new InputSource(in));
// check preferences' export version
Element preferences;
preferences = doc.getDocumentElement();
String version = preferences.getAttribute("EXTERNAL_XML_VERSION");
if (version != null && Float.parseFloat(version) > XML_VERSION) {
throw new InvalidPreferencesFormatException("Preferences version " + version +
" is not supported");
}
// check preferences root's type
Element root = (Element) preferences
.getElementsByTagName("root").item(0);
Preferences prefsRoot = null;
String type = root.getAttribute("type");
if (type.equals("user")) {
prefsRoot = Preferences.userRoot();
} else {
prefsRoot = Preferences.systemRoot();
}
// load node
loadNode(prefsRoot, root);
} catch (FactoryConfigurationError e) {
throw new InvalidPreferencesFormatException(e);
} catch (SAXException e) {
throw new InvalidPreferencesFormatException(e);
}
}
private static void loadNode(Preferences prefs, Element node) {
// load preferences
NodeList children = selectNodeList(node, "node");
NodeList entries = selectNodeList(node, "map/entry");
int childNumber = children.getLength();
Preferences[] prefChildren = new Preferences[childNumber];
int entryNumber = entries.getLength();
synchronized (((AbstractPreferences) prefs).lock) {
if (((AbstractPreferences) prefs).isRemoved()) {
return;
}
for (int i = 0; i < entryNumber; i++) {
Element entry = (Element) entries.item(i);
String key = entry.getAttribute("key");
String value = entry.getAttribute("value");
prefs.put(key, value);
}
// get children preferences node
for (int i = 0; i < childNumber; i++) {
Element child = (Element) children.item(i);
String name = child.getAttribute("name");
prefChildren[i] = prefs.node(name);
}
}
// load children nodes after unlock
for (int i = 0; i < childNumber; i++) {
loadNode(prefChildren[i], (Element) children.item(i));
}
}
// TODO dirty implementation of a method from javax.xml.xpath
// should be replaced with a call to a good impl of this method
private static NodeList selectNodeList(Element documentElement, String string) {
NodeList result = null;
ArrayList input = new ArrayList();
String[] path = string.split("/");
NodeList childNodes = documentElement.getChildNodes();
if(path[0].equals("entry") || path[0].equals("node")) {
for (int i = 0; i < childNodes.getLength(); i++) {
Object next = childNodes.item(i);
if(next instanceof Element) {
if(((Element) next).getNodeName().equals(path[0])) {
input.add((Node)next);
}
}
}
} else if(path[0].equals("map") && path[1].equals("entry")) {
for (int i = 0; i < childNodes.getLength(); i++) {
Object next = childNodes.item(i);
if(next instanceof Element) {
if(((Element) next).getNodeName().equals(path[0])) {
NodeList nextChildNodes = ((Node)next).getChildNodes();
for (int j = 0; j < nextChildNodes.getLength(); j++) {
Object subnext = nextChildNodes.item(j);
if(subnext instanceof Element) {
if(((Element)subnext).getNodeName().equals(path[1])) {
input.add((Node)subnext);
}
}
}
}
}
}
}
result = new NodeSet(input.iterator());
return result;
}
/**
* Returns the preferences from {@code xmlFile}. Returns empty properties if
* any errors occur.
*/
static Properties readXmlPreferences(File xmlFile) {
Properties result = new Properties();
if (!xmlFile.exists()) {
xmlFile.getParentFile().mkdirs();
} else if (xmlFile.canRead()) {
Reader reader = null;
try {
reader = new InputStreamReader(new FileInputStream(xmlFile), "UTF-8");
Document document = builder.parse(new InputSource(reader));
NodeList entries = selectNodeList(document.getDocumentElement(), "entry");
int length = entries.getLength();
for (int i = 0; i < length; i++) {
Element node = (Element) entries.item(i);
String key = node.getAttribute("key");
String value = node.getAttribute("value");
result.setProperty(key, value);
}
} catch (IOException ignored) {
} catch (SAXException ignored) {
} finally {
IoUtils.closeQuietly(reader);
}
} else {
// the prefs API requires this to be hostile towards pre-existing files
xmlFile.delete();
}
return result;
}
/**
* Writes the preferences to {@code xmlFile}.
*/
static void writeXmlPreferences(File xmlFile, Properties properties) throws IOException {
File parent = xmlFile.getParentFile();
File temporaryForWriting = new File(parent, "prefs-" + UUID.randomUUID() + ".xml.tmp");
BufferedWriter out = null;
try {
out = new BufferedWriter(new OutputStreamWriter(
new FileOutputStream(temporaryForWriting), "UTF-8"));
out.write(HEADER);
out.newLine();
out.write(FILE_PREFS);
out.newLine();
String[] keys = properties.keySet().toArray(new String[properties.size()]);
int length = keys.length;
String[] values = new String[length];
for (int i = 0; i < length; i++) {
values[i] = properties.getProperty(keys[i]);
}
exportEntries(keys, values, out);
out.close();
if (!temporaryForWriting.renameTo(xmlFile)) {
throw new IOException("Failed to write preferences to " + xmlFile);
}
} finally {
IoUtils.closeQuietly(out);
temporaryForWriting.delete(); // no-op unless something failed
}
}
}
