| XMLAttributePersistenceManager.java |
/***************************************
* *
* JBoss: The OpenSource J2EE WebOS *
* *
* Distributable under LGPL license. *
* See terms of license at gnu.org. *
* *
***************************************/
package org.jboss.system.pm;
import java.beans.PropertyEditor;
import java.beans.PropertyEditorManager;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FilenameFilter;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.net.URL;
import java.text.SimpleDateFormat;
import java.util.Collections;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import javax.management.Attribute;
import javax.management.AttributeList;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Result;
import javax.xml.transform.Source;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import org.jboss.logging.Logger;
import org.jboss.mx.persistence.AttributePersistenceManager;
import org.jboss.system.server.ServerConfigLocator;
import org.jboss.util.file.Files;
import org.w3c.dom.Comment;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.w3c.dom.Text;
/**
* FileAttributePersistenceManager
*
* @author <a href="mailto:dimitris@jboss.org">Dimitris Andreadis</a>
* @version $Revision: 1.3.2.1 $
**/
public class XMLAttributePersistenceManager
implements AttributePersistenceManager
{
// Constants -----------------------------------------------------
/** The XML configuration element */
public static final String DATA_DIR_ELEMENT = "data-directory";
/** Default base directory if one not specified */
public static final String DEFAULT_BASE_DIR = "data/xmbean-attrs";
/** The XML attribute-list elements and attributes */
public static final String AL_ROOT_ELEMENT = "attribute-list";
public static final String AL_ID_ATTRIBUTE = "id";
public static final String AL_DATE_ATTRIBUTE = "date";
public static final String AL_ATTRIBUTE_ELEMENT = "attribute";
public static final String AL_NAME_ATTRIBUTE = "name";
public static final String AL_TYPE_ATTRIBUTE = "type";
public static final String AL_NULL_ATTRIBUTE = "null";
public static final String AL_SERIALIZED_ATTRIBUTE = "serialized";
public static final String AL_TRUE_VALUE = "true";
public static final String AL_FALSE_VALUE = "false";
// Private Data --------------------------------------------------
/** Logger object */
private static final Logger log = Logger.getLogger(XMLAttributePersistenceManager.class);
/** used for formating timestamps (date attribute) */
private static final SimpleDateFormat dateFormat = new SimpleDateFormat("yyyyMMddHHmmss");
/** for byte-to-hex conversions */
private static final char[] hexDigits = new char[]
{ '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };
/** directory as used internally */
private File dataDir;
/** enable status */
private boolean state;
/** id to filename cache */
private Map idMap;
// Constructors -------------------------------------------------
/**
* Constructs a <tt>FileAttributePersistenceManager</tt>.
**/
public XMLAttributePersistenceManager()
{
if (log.isDebugEnabled())
log.debug("Constructed");
}
// AttributePersistenceManager Lifecycle -------------------------
/**
* Initializes the AttributePersistenceManager using
* the supplied configuration element CONFIG_ELEMENT
* whose content will be probably different for each
* particular implementation.
*
* The version string is a tag that must be used by the
* AttributePersistenceManager implementation to make
* sure that data saved/loaded under different version
* tags are partitioned.
*
* Once created, the configuration of the implementation
* object cannot change.
*
* Calling any other method before create() is executed
* will result in a IllegalStateException
*
* Finally, the implementation should be prepared to
* receive multiple concurrent calls.
*
* @param version a tag to identify the version
* @param config XML Element to load arbitrary config
* @throws Exception when any error occurs during create
*/
public void create(String version, Element config)
throws Exception
{
// ignore if already active
if (getState()) {
return;
}
// Decide on the base data directory to use
String baseDir = null;
if (config == null) {
baseDir = DEFAULT_BASE_DIR;
}
else {
if (!config.getTagName().equals(DATA_DIR_ELEMENT)) {
throw new Exception("expected '" + DATA_DIR_ELEMENT +
"' XML configuration element, got '" +
config.getTagName() + "'");
}
else {
baseDir = getElementContent(config);
}
}
// Initialize the data dir
this.dataDir = initDataDir(baseDir, version);
if (log.isDebugEnabled()) {
log.debug("Using data directory: " + this.dataDir.getCanonicalPath());
}
// initialize id cache
this.idMap = Collections.synchronizedMap(new HashMap());
// mark active status
setState(true);
}
/**
* Returns true if the AttributePersistenceManager
* is "in-service" state, i.e. after create() and
* before destroy() has been called, false otherwise.
*
* @return true if in operational state
*/
public boolean getState()
{
return this.state;
}
/**
* Releases resources and destroys the AttributePersistenceManager.
* The object is unusable after destroy() has been called.
*
* Any call to any method will result to an
* IllegalStateException.
*
*/
public void destroy()
{
setState(false);
// instance can't be use anymore
this.dataDir = null;
this.idMap = null;
}
// AttributePersistenceManager Persistence -----------------------
/**
* Uses the specified id to retrieve a previously persisted
* AttributeList. If no data can be found under the specified
* id, a null will be returned.
*
* @param id the key for retrieving the data
* @return the data, or null
* @throws Exception when an error occurs
*/
public void store(String id, AttributeList attrs)
throws Exception
{
if (log.isDebugEnabled())
log.debug("store(" + id + ") attrs=" + attrs);
// make sure we are active
checkActiveState();
// map to filename - keep the original for storing
String origId = id;
id = mapId(id);
if (attrs == null)
throw new Exception("store() called with null AttributeList");
// will throw an exception if file not r/w or it is a directory
File file = checkFileForWrite(id);
// build the XML in memory using DOM
DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
Document doc = builder.newDocument();
// Add a comment
Comment comment = doc.createComment(" automatically produced by XMLAttributePersistenceManager ");
doc.appendChild(comment);
// Insert root element
Element root = doc.createElement(AL_ROOT_ELEMENT);
root.setAttribute(AL_ID_ATTRIBUTE, origId);
root.setAttribute(AL_DATE_ATTRIBUTE, dateFormat.format(new Date()));
doc.appendChild(root);
// iterate over the AttributeList
for (int i = 0; i < attrs.size(); i++) {
Attribute attr = (Attribute)attrs.get(i);
String name = attr.getName();
Object value = attr.getValue();
// create the Element and decide how to fill it in
Element element = doc.createElement(AL_ATTRIBUTE_ELEMENT);
element.setAttribute(AL_NAME_ATTRIBUTE, name);
if (value == null) {
// (a) null value - mark it as null
element.setAttribute(AL_NULL_ATTRIBUTE, AL_TRUE_VALUE);
// append the attribute to the attribute-list
root.appendChild(element);
}
else if (value instanceof org.w3c.dom.Element) {
// (b) XML Element - mark the type and append a copy of it
element.setAttribute(AL_TYPE_ATTRIBUTE, "org.w3c.dom.Element");
Node copy = doc.importNode((org.w3c.dom.Element)value, true);
element.appendChild(copy);
// append the attribute to the attribute-list
root.appendChild(element);
}
else {
Class clazz = value.getClass();
String type = clazz.getName();
PropertyEditor peditor = PropertyEditorManager.findEditor(clazz);
if (peditor != null) {
// (c) use a PropertyEditor - mark the type and append the value as string
peditor.setValue(value);
element.setAttribute(AL_TYPE_ATTRIBUTE, type);
element.appendChild(doc.createTextNode(peditor.getAsText()));
// append the attribute to the attribute-list
root.appendChild(element);
}
else if (value instanceof Serializable) {
// (d) serialize the object - mark type and serialized attribute
// - encode the value as stringfied sequence of hex
String encoded = encodeAsHexString((Serializable)value);
if (encoded != null) {
element.setAttribute(AL_TYPE_ATTRIBUTE, type);
element.setAttribute(AL_SERIALIZED_ATTRIBUTE, AL_TRUE_VALUE);
element.appendChild(doc.createTextNode(encoded));
// append the attribute to the attribute-list
root.appendChild(element);
}
else {
// could not serialize the object - write and log a warning
root.appendChild(doc.createComment(
" WARN <attribute name=\"" + name + "\" type=\"" + type +
"\"/> could not be serialized "));
log.warn("Could not serialize attribute '" + name +
"' of type '" + type + "' and value: " + value);
}
}
else {
// (e) could not find a way to persist - record and log a warning
root.appendChild(doc.createComment(
" WARN <attribute name=\"" + name + "\" type=\"" + type +
"\"/> could not be persisted "));
log.warn("Could not find a way to persist attribute '" + name +
"' of type '" + type + "' and value: " + value);
}
}
}
// DOM document ready - save it
try {
outputXmlFile(doc, file);
}
catch (Exception e) {
log.warn("Cannot persist AttributeList to: \"" + id + "\"", e);
throw e;
}
}
/**
* Persists an AttributeList (name/value pair list),
* under a specified id. The id can be used to retrieve the
* AttributeList later on. The actual mechanism will differ
* among implementations.
*
* @param id the key for retrieving the data later on, not null
* @param attrs the data to be persisted, not null
* @throws Exception when data cannot be persisted
*/
public AttributeList load(String id)
throws Exception
{
if (log.isDebugEnabled())
log.debug("load(" + id + ")");
// make sure we are active
checkActiveState();
// map to filename
id = mapId(id);
if (!getState())
return null;
// Real stuff starts here
AttributeList attrs = null;
// returns null to indicate file does not exist
File file = checkFileForRead(id);
if (file != null) {
// parse the saved XML doc
Document doc = parseXmlFile(file);
// top level - look for AL_ROOT_ELEMENT
NodeList docList = doc.getChildNodes();
Element root = null;
for (int i = 0; i < docList.getLength(); i++) {
Node node = docList.item(i);
if (node.getNodeType() == Node.ELEMENT_NODE &&
node.getNodeName().equals(AL_ROOT_ELEMENT)) {
root = (Element)node;
break; // found
}
}
// root element must be there
if (root == null) {
throw new Exception("Expected XML element: " + AL_ROOT_ELEMENT);
}
else {
// proceed iterating over AL_ATTRIBUTE_ELEMENT elements
// and fill the AttributeList
attrs = new AttributeList();
NodeList rootList = root.getChildNodes();
for (int i = 0; i < rootList.getLength(); i++) {
Node node = rootList.item(i);
// only interested in ELEMENT nodes
if (node.getNodeType() == Node.ELEMENT_NODE &&
node.getNodeName().equals(AL_ATTRIBUTE_ELEMENT)) {
Element element = (Element)node;
// name attribute must always be there
String name = element.getAttribute(AL_NAME_ATTRIBUTE);
if (!(name.length() > 0)) {
throw new Exception("Attribute '" + AL_NAME_ATTRIBUTE +
"' must be specified for element '" + AL_ATTRIBUTE_ELEMENT + "'");
}
// Process the attribute depending on how the attributes are set
if (element.getAttribute(AL_NULL_ATTRIBUTE).toLowerCase().equals(AL_TRUE_VALUE)) {
// (a) null value - just add it to the AttributeList
attrs.add(new Attribute(name, null));
}
else if (element.getAttribute(AL_SERIALIZED_ATTRIBUTE).toLowerCase().equals(AL_TRUE_VALUE)) {
// (b) serialized value - decode the HexString
String hexStr = getElementContent(element);
Serializable obj = decodeFromHexString(hexStr);
if (obj == null) {
throw new Exception("Failed to deserialize attribute '" + name + "'");
}
else {
attrs.add(new Attribute(name, obj));
}
}
else {
String type = element.getAttribute(AL_TYPE_ATTRIBUTE);
// type must be specified
if (!(type.length() > 0)) {
throw new Exception("Attribute '" + AL_TYPE_ATTRIBUTE +
"' must be specified for name='" + name + "'");
}
if (type.equals("org.w3c.dom.Element")) {
// (c) org.w3c.dom.Element - deep copy first Element child node found
NodeList nlist = element.getChildNodes();
Element el = null;
for (int j = 0; j < nlist.getLength(); j++) {
Node n = nlist.item(j);
if (n.getNodeType() == Node.ELEMENT_NODE)
{
el = (Element)n;
break;
}
}
if (el != null) {
attrs.add(new Attribute(name, el.cloneNode(true)));
}
else {
attrs.add(new Attribute(name, null));
}
}
else {
// Get the classloader for loading attribute classes.
ClassLoader cl = Thread.currentThread().getContextClassLoader();
Class clazz = null;
try {
clazz = cl.loadClass(type);
}
catch (ClassNotFoundException e) {
throw new Exception("Class not found for attribute '" + name +
"' of type '" + type + "'");
}
PropertyEditor peditor = PropertyEditorManager.findEditor(clazz);
if (peditor != null) {
// (d) use a PropertyEditor - extract the value
String value = getElementContent(element);
peditor.setAsText(value);
attrs.add(new Attribute(name, peditor.getValue()));
}
else {
throw new Exception("Cannot find a way to load attribute '" + name +
"' of type '" + type + "'");
}
}
}
}
} // end for()
}
}
if (log.isDebugEnabled())
log.debug("load() returns with: " + attrs);
// will be null if a persistent file was not found
return attrs;
}
// Administrative Functions --------------------------------------
/**
* Checks if a persistened AttributeList for this particular
* id exists
*
* @param id the key of the image
* @return true if an image exists; false otherwise
* @throws Exception on any error
*/
public boolean exists(String id)
throws Exception
{
// make sure we are active
checkActiveState();
return (new File(this.dataDir, mapId(id))).isFile();
}
/**
* Removes the persisted AttributeList, if exists
*
* @param id the key of the image
* @throws Exception when any error occurs
*/
public void remove(String id)
throws Exception
{
// make sure we are active
checkActiveState();
(new File(this.dataDir, mapId(id))).delete();
}
/**
* Removes all the persisted data stored under
* the configured version tag.
*
* @throws Exception when any error occurs
*/
public void removeAll()
throws Exception
{
// make sure we are active
checkActiveState();
String[] files = this.dataDir.list(new XMLFilter());
if (files != null) {
for (int i = 0; i < files.length; i++) {
(new File(this.dataDir, files[i])).delete();
}
}
}
/**
* Returns a String array with all the saved ids
* under the configured version tag.
*
* @return array with all persisted ids
* @throws Exception when any error occurs
*/
public String[] listAll()
throws Exception
{
// make sure we are active
checkActiveState();
String[] files = this.dataDir.list(new XMLFilter());
String[] result = null;
if (files != null) {
result = new String[files.length];
for (int i = 0; i < files.length; i++) {
result[i] = mapFile(files[i]);
}
}
return result;
}
// Private -------------------------------------------------------
/**
* Private status setter
*
* lifecycle is controlled by create() and destroy()
*/
private void setState(boolean state)
{
this.state = state;
}
/**
* Create/check/point to the data directory.
*
* Process the base dir first and append the versionTag dir
* if specified.
*
* Only a base dir relative to ServerHomeDir is created.
* External base dirs are only used (i.e. they must exist
* and we must read/write permission)
*/
private File initDataDir(String baseDir, String versionTag)
throws Exception
{
File dir = null;
// Process the base directory first
// baseDir must be valid URL pointing to r/w dir
try {
URL fileURL = new URL(baseDir);
File file = new File(fileURL.getFile());
if(file.isDirectory() && file.canRead() && file.canWrite()) {
dir = file;
}
}
catch(Exception e) {
// Otherwise, try to make it inside the jboss directory hierarchy
File homeDir = ServerConfigLocator.locate().getServerHomeDir();
dir = new File(homeDir, baseDir);
dir.mkdirs();
if (!dir.isDirectory())
throw new Exception("The base directory is not valid: "
+ dir.getCanonicalPath());
}
// Now add the versionTag dir, if specified
if (versionTag != null && !versionTag.equals("")) {
dir = new File(dir, versionTag);
dir.mkdirs();
if (!dir.isDirectory())
throw new Exception("The data directory is not valid: "
+ dir.getCanonicalPath());
}
return dir;
}
/**
* Serialize an object as a Hex string so it can be saved as text
*
* The length of the encoded object is twice it's byte image
*
* Returns null if serialization fails
*/
private String encodeAsHexString(Serializable obj)
{
String retn = null;
if (obj != null) {
try {
ByteArrayOutputStream baos = new ByteArrayOutputStream(1024);
ObjectOutputStream oos = new ObjectOutputStream(baos);
oos.writeObject(obj);
byte[] bytes = baos.toByteArray();
StringBuffer sbuf = new StringBuffer(1024);
for (int i = 0; i < bytes.length; i++) {
sbuf.append(hexDigits[ (bytes[i] >> 4) & 0xF ]); // high order digit
sbuf.append(hexDigits[ (bytes[i] ) & 0xF ]); // low order digit
}
retn = sbuf.toString();
}
catch (IOException e) {
// will return null
}
}
return retn;
}
/**
* Deserialize an object from its hex encoded string representation
*
* Returns null if deserialization fails
*/
private Serializable decodeFromHexString(String hexStr)
{
// hexStr must not contain white space!
int len = hexStr.length() / 2;
byte[] bytes = new byte[len];
for (int i = 0; i < len; i++) {
char h1 = hexStr.charAt(i * 2); // high order hex digit
char h2 = hexStr.charAt(i * 2 + 1); // low order hex digit
// convert hex digits to integers
int d1 = (h1 >= 'a') ? (10 + h1 - 'a')
: ((h1 >= 'A') ? (10 + h1 - 'A')
: (h1 - '0'));
int d2 = (h2 >= 'a') ? (10 + h2 - 'a')
: ((h2 >= 'A') ? (10 + h2 - 'A')
: (h2 - '0'));
bytes[i] = (byte)(d1 * 16 + d2); // 255 max
}
Serializable retn = null;
try {
ByteArrayInputStream bais = new ByteArrayInputStream(bytes);
ObjectInputStream ois = new ObjectInputStream(bais);
retn = (Serializable)ois.readObject();
}
catch (IOException e) {
log.warn("Cannot deserialize object", e); }
catch (ClassNotFoundException e) {
log.warn("Cannot deserialize object", e);
}
return retn;
}
/**
* Just output a DOM Document to a file with
* indentation true
*/
private void outputXmlFile(Document doc, File file)
throws Exception
{
// Prepare the DOM document for writing
Source source = new DOMSource(doc);
// Prepare the output file
Result result = new StreamResult(file);
// Write the DOM document to the file
Transformer xformer = TransformerFactory.newInstance().newTransformer();
// Enable indentation
xformer.setOutputProperty(OutputKeys.INDENT, "yes");
xformer.transform(source, result);
}
/**
* Parse an XML file into a DOM Document
* with validation set to false
*/
private Document parseXmlFile(File file)
throws Exception
{
// Create a builder factory
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
// do not request validation against DTD
// no DTD specified in the saved document
factory.setValidating(false);
// Create the builder and parse the file
Document doc = factory.newDocumentBuilder().parse(file);
return doc;
}
/**
* Makes sure we can write to this file
*/
private File checkFileForWrite(String filename)
throws Exception
{
File file = new File(this.dataDir, filename);
if (file.isFile()) {
if (file.canRead() && file.canWrite()) {
return file; // everything fine
}
else {
throw new Exception("file '" + filename + "' is not r/w"); // oops
}
}
else if (file.isDirectory()) {
throw new Exception(filename + " is a directory!"); // oops
}
else {
return file; // not found - ok
}
}
/**
* Makes sure we can read from this file.
*
* Returns null if not found
*/
private File checkFileForRead(String filename)
throws Exception
{
File file = new File(this.dataDir, filename);
if (file.isFile()) {
if (file.canRead() && file.canWrite()) {
return file; // everything fine
}
else {
throw new Exception("file '" + filename + "' is not r/w"); // oops
}
}
else if (file.isDirectory()) {
throw new Exception(filename + " is a directory!"); // oops
}
else {
return null; // not found
}
}
/**
* Returns the concatenated content of all
* children TEXT nodes of this element
*/
private String getElementContent(Element element)
{
NodeList nlist = element.getChildNodes();
StringBuffer sbuf = new StringBuffer(1024);
// concatenate Text nodes
for (int i = 0; i < nlist.getLength(); i++) {
Node node = nlist.item(i);
if (node.getNodeType() == Node.TEXT_NODE) {
sbuf.append(((Text)node).getData());
}
}
return sbuf.toString();
}
/**
* Make sure we are active before processing a call
*/
private void checkActiveState()
{
if (!getState()) {
throw new IllegalStateException("AttributePersistenceManager not active");
}
}
/**
* Simple filter for .xml files in a directory listing
*/
private class XMLFilter
implements FilenameFilter
{
public boolean accept(File dir, String name)
{
return name.endsWith(".xml");
}
}
/**
* Map the id to a filename and cache it
*
* A null id results in an exception thrown
*/
private String mapId(String id)
throws Exception
{
if (id == null) {
throw new Exception("called with null id");
}
else {
// check the cache
String file = (String)this.idMap.get(id);
// if not in cache encode, and cache it
if (file == null) {
file = Files.encodeFileName(id) + ".xml";
this.idMap.put(id, file);
}
return file;
}
}
/**
* Do the reverse mapping file to id
*/
private String mapFile(String file)
{
if (file == null) {
return null;
}
else {
// remove .xml suffix
file = file.substring(0, file.length() - 4);
return Files.decodeFileName(file);
}
}
}
| XMLAttributePersistenceManager.java |