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/** * Copyright (c) 2001, Thai Open Source Software Center Ltd * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are * met: * * Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * * Neither the name of the Thai Open Source Software Center Ltd nor * the names of its contributors may be used to endorse or promote * products derived from this software without specific prior written * permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ package org.relaxng.datatype.helpers; import org.relaxng.datatype.DatatypeLibraryFactory; import org.relaxng.datatype.DatatypeLibrary; import java.util.Enumeration; import java.util.NoSuchElementException; import java.util.Vector; import java.io.Reader; import java.io.InputStream; import java.io.InputStreamReader; import java.io.BufferedReader; import java.io.IOException; import java.io.UnsupportedEncodingException; import java.net.URL; /** * Discovers the datatype library implementation from the classpath. * * <p> * The call of the createDatatypeLibrary method finds an implementation * from a given datatype library URI at run-time. */ public class DatatypeLibraryLoader implements DatatypeLibraryFactory { private final Service service = new Service(DatatypeLibraryFactory.class); public DatatypeLibrary createDatatypeLibrary(String uri) { for (Enumeration e = service.getProviders(); e.hasMoreElements();) { DatatypeLibraryFactory factory = (DatatypeLibraryFactory)e.nextElement(); DatatypeLibrary library = factory.createDatatypeLibrary(uri); if (library != null) return library; } return null; } private static class Service { private final Class serviceClass; private final Enumeration configFiles; private Enumeration classNames = null; private final Vector providers = new Vector(); private Loader loader; private class ProviderEnumeration implements Enumeration { private int nextIndex = 0; public boolean hasMoreElements() { return nextIndex < providers.size() || moreProviders(); } public Object nextElement() { try { return providers.elementAt(nextIndex++); } catch (ArrayIndexOutOfBoundsException e) { throw new NoSuchElementException(); } } } private static class Singleton implements Enumeration { private Object obj; private Singleton(Object obj) { this.obj = obj; } public boolean hasMoreElements() { return obj != null; } public Object nextElement() { if (obj == null) throw new NoSuchElementException(); Object tem = obj; obj = null; return tem; } } // JDK 1.1 private static class Loader { Enumeration getResources(String resName) { ClassLoader cl = Loader.class.getClassLoader(); URL url; if (cl == null) url = ClassLoader.getSystemResource(resName); else url = cl.getResource(resName); return new Singleton(url); } Class loadClass(String name) throws ClassNotFoundException { return Class.forName(name); } } // JDK 1.2+ private static class Loader2 extends Loader { private ClassLoader cl; Loader2() { cl = Loader2.class.getClassLoader(); // If the thread context class loader has the class loader // of this class as an ancestor, use the thread context class // loader. Otherwise, the thread context class loader // probably hasn't been set up properly, so don't use it. ClassLoader clt = Thread.currentThread().getContextClassLoader(); for (ClassLoader tem = clt; tem != null; tem = tem.getParent()) if (tem == cl) { cl = clt; break; } } Enumeration getResources(String resName) { try { return cl.getResources(resName); } catch (IOException e) { return new Singleton(null); } } Class loadClass(String name) throws ClassNotFoundException { return Class.forName(name, true, cl); } } public Service(Class cls) { try { loader = new Loader2(); } catch (NoSuchMethodError e) { loader = new Loader(); } serviceClass = cls; String resName = "META-INF/services/" + serviceClass.getName(); configFiles = loader.getResources(resName); } public Enumeration getProviders() { return new ProviderEnumeration(); } synchronized private boolean moreProviders() { for (;;) { while (classNames == null) { if (!configFiles.hasMoreElements()) return false; classNames = parseConfigFile((URL)configFiles.nextElement()); } while (classNames.hasMoreElements()) { String className = (String)classNames.nextElement(); try { Class cls = loader.loadClass(className); Object obj = cls.newInstance(); if (serviceClass.isInstance(obj)) { providers.addElement(obj); return true; } } catch (ClassNotFoundException e) { } catch (InstantiationException e) { } catch (IllegalAccessException e) { } catch (LinkageError e) { } } classNames = null; } } private static final int START = 0; private static final int IN_NAME = 1; private static final int IN_COMMENT = 2; private static Enumeration parseConfigFile(URL url) { try { InputStream in = url.openStream(); Reader r; try { r = new InputStreamReader(in, "UTF-8"); } catch (UnsupportedEncodingException e) { r = new InputStreamReader(in, "UTF8"); } r = new BufferedReader(r); Vector tokens = new Vector(); StringBuffer tokenBuf = new StringBuffer(); int state = START; for (;;) { int n = r.read(); if (n < 0) break; char c = (char)n; switch (c) { case '\r': case '\n': state = START; break; case ' ': case '\t': break; case '#': state = IN_COMMENT; break; default: if (state != IN_COMMENT) { state = IN_NAME; tokenBuf.append(c); } break; } if (tokenBuf.length() != 0 && state != IN_NAME) { tokens.addElement(tokenBuf.toString()); tokenBuf.setLength(0); } } if (tokenBuf.length() != 0) tokens.addElement(tokenBuf.toString()); return tokens.elements(); } catch (IOException e) { return null; } } } }