android-35/javax/xml/xpath/XPathFactoryFinder.java - platform/prebuilts/fullsdk/sources - Git at Google

 /*
  * 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.
  */
 // $Id: XPathFactoryFinder.java 670432 2008-06-23 02:02:08Z mrglavas $

 package javax.xml.xpath;

 import java.io.BufferedReader;
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.net.URL;
 import java.util.Collections;
 import java.util.Enumeration;
 import java.util.Iterator;
 import java.util.Properties;
 import javax.xml.validation.SchemaFactory;
 import libcore.io.IoUtils;

 /**
  * Implementation of {@link XPathFactory#newInstance(String)}.
  *
  * @author <a href="[email protected]">Kohsuke Kawaguchi</a>
  * @version $Revision: 670432 $, $Date: 2008-06-22 19:02:08 -0700 (Sun, 22 Jun 2008) $
  * @since 1.5
  */
 final class XPathFactoryFinder {

     /** debug support code. */
     private static boolean debug = false;

     /**
      * Default columns per line.
      */
     private static final int DEFAULT_LINE_LENGTH = 80;

     static {
         String val = System.getProperty("jaxp.debug");
         // Allow simply setting the prop to turn on debug
         debug = val != null && (! "false".equals(val));
     }

     /**
      * <p>Cache properties for performance. Use a static class to avoid double-checked
      * locking.</p>
      */
     private static class CacheHolder {

         private static Properties cacheProps = new Properties();

         static {
             String javah = System.getProperty("java.home");
             String configFile = javah + File.separator + "lib" + File.separator + "jaxp.properties";
             File f = new File(configFile);
             if (f.exists()) {
                 if (debug) debugPrintln("Read properties file " + f);
                 try (FileInputStream inputStream = new FileInputStream(f)) {
                     cacheProps.load(inputStream);
                 } catch (Exception ex) {
                     if (debug) {
                         ex.printStackTrace();
                     }
                 }
             }
         }
     }

     /**
      * <p>Conditional debug printing.</p>
      *
      * @param msg to print
      */
     private static void debugPrintln(String msg) {
         if (debug) {
             System.err.println("JAXP: " + msg);
         }
     }

     /**
      * <p><code>ClassLoader</code> to use to find <code>SchemaFactory</code>.</p>
      */
     private final ClassLoader classLoader;

     /**
      * <p>Constructor that specifies <code>ClassLoader</code> to use
      * to find <code>SchemaFactory</code>.</p>
      *
      * @param loader
      *      to be used to load resource, {@link SchemaFactory}, and
      *      {@code SchemaFactoryLoader} implementations during
      *      the resolution process.
      *      If this parameter is null, the default system class loader
      *      will be used.
      */
     public XPathFactoryFinder(ClassLoader loader) {
         this.classLoader = loader;
         if (debug) {
             debugDisplayClassLoader();
         }
     }

     private void debugDisplayClassLoader() {
         if (classLoader == Thread.currentThread().getContextClassLoader()) {
             debugPrintln("using thread context class loader (" + classLoader + ") for search");
             return;
         }

         if (classLoader==ClassLoader.getSystemClassLoader()) {
             debugPrintln("using system class loader (" + classLoader + ") for search");
             return;
         }

         debugPrintln("using class loader (" + classLoader + ") for search");
     }

     /**
      * <p>Creates a new {@link XPathFactory} object for the specified
      * schema language.</p>
      *
      * @param uri
      *       Identifies the underlying object model.
      *
      * @return <code>null</code> if the callee fails to create one.
      *
      * @throws NullPointerException
      *      If the parameter is null.
      */
     public XPathFactory newFactory(String uri) {
         if (uri == null) {
             throw new NullPointerException("uri == null");
         }
         XPathFactory f = _newFactory(uri);
         if (debug) {
             if (f != null) {
                 debugPrintln("factory '" + f.getClass().getName() + "' was found for " + uri);
             } else {
                 debugPrintln("unable to find a factory for " + uri);
             }
         }
         return f;
     }

     /**
      * <p>Lookup a {@link XPathFactory} for the given object model.</p>
      *
      * @param uri identifies the object model.
      */
     private XPathFactory _newFactory(String uri) {
         XPathFactory xpf;
         String propertyName = SERVICE_CLASS.getName() + ":" + uri;

         // system property look up
         try {
             if (debug) debugPrintln("Looking up system property '"+propertyName+"'" );
             String r = System.getProperty(propertyName);
             if (r != null && r.length() > 0) {
                 if (debug) debugPrintln("The value is '"+r+"'");
                 xpf = createInstance(r);
                 if(xpf!=null)    return xpf;
             } else if (debug) {
                 debugPrintln("The property is undefined.");
             }
         } catch (Exception e) {
             e.printStackTrace();
         }

         // try to read from $java.home/lib/jaxp.properties
         try {
             String factoryClassName = CacheHolder.cacheProps.getProperty(propertyName);
             if (debug) debugPrintln("found " + factoryClassName + " in $java.home/jaxp.properties");

             if (factoryClassName != null) {
                 xpf = createInstance(factoryClassName);
                 if(xpf != null){
                     return xpf;
                 }
             }
         } catch (Exception ex) {
             if (debug) {
                 ex.printStackTrace();
             }
         }

         // try META-INF/services files
         for (URL resource : createServiceFileIterator()) {
             if (debug) debugPrintln("looking into " + resource);
             try {
                 xpf = loadFromServicesFile(uri, resource.toExternalForm(), resource.openStream());
                 if(xpf!=null)    return xpf;
             } catch(IOException e) {
                 if( debug ) {
                     debugPrintln("failed to read "+resource);
                     e.printStackTrace();
                 }
             }
         }

         // platform default
         if(uri.equals(XPathFactory.DEFAULT_OBJECT_MODEL_URI)) {
             if (debug) debugPrintln("attempting to use the platform default W3C DOM XPath lib");
             return createInstance("org.apache.xpath.jaxp.XPathFactoryImpl");
         }

         if (debug) debugPrintln("all things were tried, but none was found. bailing out.");
         return null;
     }

     /**
      * <p>Creates an instance of the specified and returns it.</p>
      *
      * @param className
      *      fully qualified class name to be instantiated.
      *
      * @return null
      *      if it fails. Error messages will be printed by this method.
      */
     XPathFactory createInstance( String className ) {
         try {
             if (debug) debugPrintln("instantiating "+className);
             Class clazz;
             if( classLoader!=null )
                 clazz = classLoader.loadClass(className);
             else
                 clazz = Class.forName(className);
             if(debug)       debugPrintln("loaded it from "+which(clazz));
             Object o = clazz.newInstance();

             if( o instanceof XPathFactory )
                 return (XPathFactory)o;

             if (debug) debugPrintln(className+" is not assignable to "+SERVICE_CLASS.getName());
         }
         // The VM ran out of memory or there was some other serious problem. Re-throw.
         catch (VirtualMachineError vme) {
             throw vme;
         }
         // ThreadDeath should always be re-thrown
         catch (ThreadDeath td) {
             throw td;
         }
         catch (Throwable t) {
             if (debug) {
                 debugPrintln("failed to instantiate "+className);
                 t.printStackTrace();
             }
         }
         return null;
     }

     /** Searches for a XPathFactory for a given uri in a META-INF/services file. */
     private XPathFactory loadFromServicesFile(String uri, String resourceName, InputStream in) {

         if (debug) debugPrintln("Reading " + resourceName );

         BufferedReader rd;
         try {
             rd = new BufferedReader(new InputStreamReader(in, "UTF-8"), DEFAULT_LINE_LENGTH);
         } catch (java.io.UnsupportedEncodingException e) {
             rd = new BufferedReader(new InputStreamReader(in), DEFAULT_LINE_LENGTH);
         }

         String factoryClassName;
         XPathFactory resultFactory = null;
         // See spec for provider-configuration files: http://java.sun.com/j2se/1.5.0/docs/guide/jar/jar.html#Provider%20Configuration%20File
         while (true) {
             try {
                 factoryClassName = rd.readLine();
             } catch (IOException x) {
                 // No provider found
                 break;
             }
             if (factoryClassName != null) {
                 // Ignore comments in the provider-configuration file
                 int hashIndex = factoryClassName.indexOf('#');
                 if (hashIndex != -1) {
                     factoryClassName = factoryClassName.substring(0, hashIndex);
                 }

                 // Ignore leading and trailing whitespace
                 factoryClassName = factoryClassName.trim();

                 // If there's no text left or if this was a blank line, go to the next one.
                 if (factoryClassName.length() == 0) {
                     continue;
                 }

                 try {
                     // Found the right XPathFactory if its isObjectModelSupported(String uri) method returns true.
                     XPathFactory foundFactory = createInstance(factoryClassName);
                     if (foundFactory.isObjectModelSupported(uri)) {
                         resultFactory = foundFactory;
                         break;
                     }
                 } catch (Exception ignored) {
                 }
             }
             else {
                 break;
             }
         }

         IoUtils.closeQuietly(rd);

         return resultFactory;
     }

     /**
      * Returns an {@link Iterator} that enumerates all
      * the META-INF/services files that we care.
      */
     private Iterable<URL> createServiceFileIterator() {
         if (classLoader == null) {
             URL resource = XPathFactoryFinder.class.getClassLoader().getResource(SERVICE_ID);
             return Collections.singleton(resource);
         } else {
             try {
                 Enumeration<URL> e = classLoader.getResources(SERVICE_ID);
                 if (debug && !e.hasMoreElements()) {
                     debugPrintln("no "+SERVICE_ID+" file was found");
                 }

                 return Collections.list(e);
             } catch (IOException e) {
                 if (debug) {
                     debugPrintln("failed to enumerate resources "+SERVICE_ID);
                     e.printStackTrace();
                 }
                 return Collections.emptySet();
             }
         }
     }

     private static final Class SERVICE_CLASS = XPathFactory.class;
     private static final String SERVICE_ID = "META-INF/services/" + SERVICE_CLASS.getName();

     private static String which( Class clazz ) {
         return which( clazz.getName(), clazz.getClassLoader() );
     }

     /**
      * <p>Search the specified classloader for the given classname.</p>
      *
      * @param classname the fully qualified name of the class to search for
      * @param loader the classloader to search
      *
      * @return the source location of the resource, or null if it wasn't found
      */
     private static String which(String classname, ClassLoader loader) {
         String classnameAsResource = classname.replace('.', '/') + ".class";
         if (loader==null) loader = ClassLoader.getSystemClassLoader();

         URL it = loader.getResource(classnameAsResource);
         return it != null ? it.toString() : null;
     }
 }
	/*
	* 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.
	*/
	// $Id: XPathFactoryFinder.java 670432 2008-06-23 02:02:08Z mrglavas $

	package javax.xml.xpath;

	import java.io.BufferedReader;
	import java.io.File;
	import java.io.FileInputStream;
	import java.io.IOException;
	import java.io.InputStream;
	import java.io.InputStreamReader;
	import java.net.URL;
	import java.util.Collections;
	import java.util.Enumeration;
	import java.util.Iterator;
	import java.util.Properties;
	import javax.xml.validation.SchemaFactory;
	import libcore.io.IoUtils;

	/**
	* Implementation of {@link XPathFactory#newInstance(String)}.
	*
	* @author <a href="[email protected]">Kohsuke Kawaguchi</a>
	* @version $Revision: 670432 $, $Date: 2008-06-22 19:02:08 -0700 (Sun, 22 Jun 2008) $
	* @since 1.5
	*/
	final class XPathFactoryFinder {

	/** debug support code. */
	private static boolean debug = false;

	/**
	* Default columns per line.
	*/
	private static final int DEFAULT_LINE_LENGTH = 80;

	static {
	String val = System.getProperty("jaxp.debug");
	// Allow simply setting the prop to turn on debug
	debug = val != null && (! "false".equals(val));
	}

	/**
	* <p>Cache properties for performance. Use a static class to avoid double-checked
	* locking.</p>
	*/
	private static class CacheHolder {

	private static Properties cacheProps = new Properties();

	static {
	String javah = System.getProperty("java.home");
	String configFile = javah + File.separator + "lib" + File.separator + "jaxp.properties";
	File f = new File(configFile);
	if (f.exists()) {
	if (debug) debugPrintln("Read properties file " + f);
	try (FileInputStream inputStream = new FileInputStream(f)) {
	cacheProps.load(inputStream);
	} catch (Exception ex) {
	if (debug) {
	ex.printStackTrace();
	}
	}
	}
	}
	}

	/**
	* <p>Conditional debug printing.</p>
	*
	* @param msg to print
	*/
	private static void debugPrintln(String msg) {
	if (debug) {
	System.err.println("JAXP: " + msg);
	}
	}

	/**
	* <p><code>ClassLoader</code> to use to find <code>SchemaFactory</code>.</p>
	*/
	private final ClassLoader classLoader;

	/**
	* <p>Constructor that specifies <code>ClassLoader</code> to use
	* to find <code>SchemaFactory</code>.</p>
	*
	* @param loader
	* to be used to load resource, {@link SchemaFactory}, and
	* {@code SchemaFactoryLoader} implementations during
	* the resolution process.
	* If this parameter is null, the default system class loader
	* will be used.
	*/
	public XPathFactoryFinder(ClassLoader loader) {
	this.classLoader = loader;
	if (debug) {
	debugDisplayClassLoader();
	}
	}

	private void debugDisplayClassLoader() {
	if (classLoader == Thread.currentThread().getContextClassLoader()) {
	debugPrintln("using thread context class loader (" + classLoader + ") for search");
	return;
	}

	if (classLoader==ClassLoader.getSystemClassLoader()) {
	debugPrintln("using system class loader (" + classLoader + ") for search");
	return;
	}

	debugPrintln("using class loader (" + classLoader + ") for search");
	}

	/**
	* <p>Creates a new {@link XPathFactory} object for the specified
	* schema language.</p>
	*
	* @param uri
	* Identifies the underlying object model.
	*
	* @return <code>null</code> if the callee fails to create one.
	*
	* @throws NullPointerException
	* If the parameter is null.
	*/
	public XPathFactory newFactory(String uri) {
	if (uri == null) {
	throw new NullPointerException("uri == null");
	}
	XPathFactory f = _newFactory(uri);
	if (debug) {
	if (f != null) {
	debugPrintln("factory '" + f.getClass().getName() + "' was found for " + uri);
	} else {
	debugPrintln("unable to find a factory for " + uri);
	}
	}
	return f;
	}

	/**
	* <p>Lookup a {@link XPathFactory} for the given object model.</p>
	*
	* @param uri identifies the object model.
	*/
	private XPathFactory _newFactory(String uri) {
	XPathFactory xpf;
	String propertyName = SERVICE_CLASS.getName() + ":" + uri;

	// system property look up
	try {
	if (debug) debugPrintln("Looking up system property '"+propertyName+"'" );
	String r = System.getProperty(propertyName);
	if (r != null && r.length() > 0) {
	if (debug) debugPrintln("The value is '"+r+"'");
	xpf = createInstance(r);
	if(xpf!=null) return xpf;
	} else if (debug) {
	debugPrintln("The property is undefined.");
	}
	} catch (Exception e) {
	e.printStackTrace();
	}

	// try to read from $java.home/lib/jaxp.properties
	try {
	String factoryClassName = CacheHolder.cacheProps.getProperty(propertyName);
	if (debug) debugPrintln("found " + factoryClassName + " in $java.home/jaxp.properties");

	if (factoryClassName != null) {
	xpf = createInstance(factoryClassName);
	if(xpf != null){
	return xpf;
	}
	}
	} catch (Exception ex) {
	if (debug) {
	ex.printStackTrace();
	}
	}

	// try META-INF/services files
	for (URL resource : createServiceFileIterator()) {
	if (debug) debugPrintln("looking into " + resource);
	try {
	xpf = loadFromServicesFile(uri, resource.toExternalForm(), resource.openStream());
	if(xpf!=null) return xpf;
	} catch(IOException e) {
	if( debug ) {
	debugPrintln("failed to read "+resource);
	e.printStackTrace();
	}
	}
	}

	// platform default
	if(uri.equals(XPathFactory.DEFAULT_OBJECT_MODEL_URI)) {
	if (debug) debugPrintln("attempting to use the platform default W3C DOM XPath lib");
	return createInstance("org.apache.xpath.jaxp.XPathFactoryImpl");
	}

	if (debug) debugPrintln("all things were tried, but none was found. bailing out.");
	return null;
	}

	/**
	* <p>Creates an instance of the specified and returns it.</p>
	*
	* @param className
	* fully qualified class name to be instantiated.
	*
	* @return null
	* if it fails. Error messages will be printed by this method.
	*/
	XPathFactory createInstance( String className ) {
	try {
	if (debug) debugPrintln("instantiating "+className);
	Class clazz;
	if( classLoader!=null )
	clazz = classLoader.loadClass(className);
	else
	clazz = Class.forName(className);
	if(debug) debugPrintln("loaded it from "+which(clazz));
	Object o = clazz.newInstance();

	if( o instanceof XPathFactory )
	return (XPathFactory)o;

	if (debug) debugPrintln(className+" is not assignable to "+SERVICE_CLASS.getName());
	}
	// The VM ran out of memory or there was some other serious problem. Re-throw.
	catch (VirtualMachineError vme) {
	throw vme;
	}
	// ThreadDeath should always be re-thrown
	catch (ThreadDeath td) {
	throw td;
	}
	catch (Throwable t) {
	if (debug) {
	debugPrintln("failed to instantiate "+className);
	t.printStackTrace();
	}
	}
	return null;
	}

	/** Searches for a XPathFactory for a given uri in a META-INF/services file. */
	private XPathFactory loadFromServicesFile(String uri, String resourceName, InputStream in) {

	if (debug) debugPrintln("Reading " + resourceName );

	BufferedReader rd;
	try {
	rd = new BufferedReader(new InputStreamReader(in, "UTF-8"), DEFAULT_LINE_LENGTH);
	} catch (java.io.UnsupportedEncodingException e) {
	rd = new BufferedReader(new InputStreamReader(in), DEFAULT_LINE_LENGTH);
	}

	String factoryClassName;
	XPathFactory resultFactory = null;
	// See spec for provider-configuration files: http://java.sun.com/j2se/1.5.0/docs/guide/jar/jar.html#Provider%20Configuration%20File
	while (true) {
	try {
	factoryClassName = rd.readLine();
	} catch (IOException x) {
	// No provider found
	break;
	}
	if (factoryClassName != null) {
	// Ignore comments in the provider-configuration file
	int hashIndex = factoryClassName.indexOf('#');
	if (hashIndex != -1) {
	factoryClassName = factoryClassName.substring(0, hashIndex);
	}

	// Ignore leading and trailing whitespace
	factoryClassName = factoryClassName.trim();

	// If there's no text left or if this was a blank line, go to the next one.
	if (factoryClassName.length() == 0) {
	continue;
	}

	try {
	// Found the right XPathFactory if its isObjectModelSupported(String uri) method returns true.
	XPathFactory foundFactory = createInstance(factoryClassName);
	if (foundFactory.isObjectModelSupported(uri)) {
	resultFactory = foundFactory;
	break;
	}
	} catch (Exception ignored) {
	}
	}
	else {
	break;
	}
	}

	IoUtils.closeQuietly(rd);

	return resultFactory;
	}

	/**
	* Returns an {@link Iterator} that enumerates all
	* the META-INF/services files that we care.
	*/
	private Iterable<URL> createServiceFileIterator() {
	if (classLoader == null) {
	URL resource = XPathFactoryFinder.class.getClassLoader().getResource(SERVICE_ID);
	return Collections.singleton(resource);
	} else {
	try {
	Enumeration<URL> e = classLoader.getResources(SERVICE_ID);
	if (debug && !e.hasMoreElements()) {
	debugPrintln("no "+SERVICE_ID+" file was found");
	}

	return Collections.list(e);
	} catch (IOException e) {
	if (debug) {
	debugPrintln("failed to enumerate resources "+SERVICE_ID);
	e.printStackTrace();
	}
	return Collections.emptySet();
	}
	}
	}

	private static final Class SERVICE_CLASS = XPathFactory.class;
	private static final String SERVICE_ID = "META-INF/services/" + SERVICE_CLASS.getName();

	private static String which( Class clazz ) {
	return which( clazz.getName(), clazz.getClassLoader() );
	}

	/**
	* <p>Search the specified classloader for the given classname.</p>
	*
	* @param classname the fully qualified name of the class to search for
	* @param loader the classloader to search
	*
	* @return the source location of the resource, or null if it wasn't found
	*/
	private static String which(String classname, ClassLoader loader) {
	String classnameAsResource = classname.replace('.', '/') + ".class";
	if (loader==null) loader = ClassLoader.getSystemClassLoader();

	URL it = loader.getResource(classnameAsResource);
	return it != null ? it.toString() : null;
	}
	}