J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /** |
| 2 | * Copyright (c) 2001, Thai Open Source Software Center Ltd |
| 3 | * All rights reserved. |
| 4 | * |
| 5 | * Redistribution and use in source and binary forms, with or without |
| 6 | * modification, are permitted provided that the following conditions are |
| 7 | * met: |
| 8 | * |
| 9 | * Redistributions of source code must retain the above copyright |
| 10 | * notice, this list of conditions and the following disclaimer. |
| 11 | * |
| 12 | * Redistributions in binary form must reproduce the above copyright |
| 13 | * notice, this list of conditions and the following disclaimer in |
| 14 | * the documentation and/or other materials provided with the |
| 15 | * distribution. |
| 16 | * |
| 17 | * Neither the name of the Thai Open Source Software Center Ltd nor |
| 18 | * the names of its contributors may be used to endorse or promote |
| 19 | * products derived from this software without specific prior written |
| 20 | * permission. |
| 21 | * |
| 22 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| 23 | * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| 24 | * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| 25 | * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR |
| 26 | * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
| 27 | * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
| 28 | * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR |
| 29 | * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF |
| 30 | * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING |
| 31 | * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS |
| 32 | * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 33 | */ |
| 34 | package org.relaxng.datatype.helpers; |
| 35 | |
| 36 | import org.relaxng.datatype.DatatypeLibraryFactory; |
| 37 | import org.relaxng.datatype.DatatypeLibrary; |
| 38 | import java.util.Enumeration; |
| 39 | import java.util.NoSuchElementException; |
| 40 | import java.util.Vector; |
| 41 | import java.io.Reader; |
| 42 | import java.io.InputStream; |
| 43 | import java.io.InputStreamReader; |
| 44 | import java.io.BufferedReader; |
| 45 | import java.io.IOException; |
| 46 | import java.io.UnsupportedEncodingException; |
| 47 | import java.net.URL; |
| 48 | |
| 49 | /** |
| 50 | * Discovers the datatype library implementation from the classpath. |
| 51 | * |
| 52 | * <p> |
| 53 | * The call of the createDatatypeLibrary method finds an implementation |
| 54 | * from a given datatype library URI at run-time. |
| 55 | */ |
| 56 | public class DatatypeLibraryLoader implements DatatypeLibraryFactory { |
| 57 | private final Service service = new Service(DatatypeLibraryFactory.class); |
| 58 | |
| 59 | public DatatypeLibrary createDatatypeLibrary(String uri) { |
| 60 | for (Enumeration e = service.getProviders(); |
| 61 | e.hasMoreElements();) { |
| 62 | DatatypeLibraryFactory factory |
| 63 | = (DatatypeLibraryFactory)e.nextElement(); |
| 64 | DatatypeLibrary library = factory.createDatatypeLibrary(uri); |
| 65 | if (library != null) |
| 66 | return library; |
| 67 | } |
| 68 | return null; |
| 69 | } |
| 70 | |
| 71 | private static class Service { |
| 72 | private final Class serviceClass; |
| 73 | private final Enumeration configFiles; |
| 74 | private Enumeration classNames = null; |
| 75 | private final Vector providers = new Vector(); |
| 76 | private Loader loader; |
| 77 | |
| 78 | private class ProviderEnumeration implements Enumeration { |
| 79 | private int nextIndex = 0; |
| 80 | |
| 81 | public boolean hasMoreElements() { |
| 82 | return nextIndex < providers.size() || moreProviders(); |
| 83 | } |
| 84 | |
| 85 | public Object nextElement() { |
| 86 | try { |
| 87 | return providers.elementAt(nextIndex++); |
| 88 | } |
| 89 | catch (ArrayIndexOutOfBoundsException e) { |
| 90 | throw new NoSuchElementException(); |
| 91 | } |
| 92 | } |
| 93 | } |
| 94 | |
| 95 | private static class Singleton implements Enumeration { |
| 96 | private Object obj; |
| 97 | private Singleton(Object obj) { |
| 98 | this.obj = obj; |
| 99 | } |
| 100 | |
| 101 | public boolean hasMoreElements() { |
| 102 | return obj != null; |
| 103 | } |
| 104 | |
| 105 | public Object nextElement() { |
| 106 | if (obj == null) |
| 107 | throw new NoSuchElementException(); |
| 108 | Object tem = obj; |
| 109 | obj = null; |
| 110 | return tem; |
| 111 | } |
| 112 | } |
| 113 | |
| 114 | // JDK 1.1 |
| 115 | private static class Loader { |
| 116 | Enumeration getResources(String resName) { |
| 117 | ClassLoader cl = Loader.class.getClassLoader(); |
| 118 | URL url; |
| 119 | if (cl == null) |
| 120 | url = ClassLoader.getSystemResource(resName); |
| 121 | else |
| 122 | url = cl.getResource(resName); |
| 123 | return new Singleton(url); |
| 124 | } |
| 125 | |
| 126 | Class loadClass(String name) throws ClassNotFoundException { |
| 127 | return Class.forName(name); |
| 128 | } |
| 129 | } |
| 130 | |
| 131 | // JDK 1.2+ |
| 132 | private static class Loader2 extends Loader { |
| 133 | private ClassLoader cl; |
| 134 | |
| 135 | Loader2() { |
| 136 | cl = Loader2.class.getClassLoader(); |
| 137 | // If the thread context class loader has the class loader |
| 138 | // of this class as an ancestor, use the thread context class |
| 139 | // loader. Otherwise, the thread context class loader |
| 140 | // probably hasn't been set up properly, so don't use it. |
| 141 | ClassLoader clt = Thread.currentThread().getContextClassLoader(); |
| 142 | for (ClassLoader tem = clt; tem != null; tem = tem.getParent()) |
| 143 | if (tem == cl) { |
| 144 | cl = clt; |
| 145 | break; |
| 146 | } |
| 147 | } |
| 148 | |
| 149 | Enumeration getResources(String resName) { |
| 150 | try { |
| 151 | return cl.getResources(resName); |
| 152 | |
| 153 | } |
| 154 | catch (IOException e) { |
| 155 | return new Singleton(null); |
| 156 | } |
| 157 | } |
| 158 | |
| 159 | Class loadClass(String name) throws ClassNotFoundException { |
| 160 | return Class.forName(name, true, cl); |
| 161 | } |
| 162 | } |
| 163 | |
| 164 | public Service(Class cls) { |
| 165 | try { |
| 166 | loader = new Loader2(); |
| 167 | } |
| 168 | catch (NoSuchMethodError e) { |
| 169 | loader = new Loader(); |
| 170 | } |
| 171 | serviceClass = cls; |
| 172 | String resName = "META-INF/services/" + serviceClass.getName(); |
| 173 | configFiles = loader.getResources(resName); |
| 174 | } |
| 175 | |
| 176 | public Enumeration getProviders() { |
| 177 | return new ProviderEnumeration(); |
| 178 | } |
| 179 | |
| 180 | synchronized private boolean moreProviders() { |
| 181 | for (;;) { |
| 182 | while (classNames == null) { |
| 183 | if (!configFiles.hasMoreElements()) |
| 184 | return false; |
| 185 | classNames = parseConfigFile((URL)configFiles.nextElement()); |
| 186 | } |
| 187 | while (classNames.hasMoreElements()) { |
| 188 | String className = (String)classNames.nextElement(); |
| 189 | try { |
| 190 | Class cls = loader.loadClass(className); |
| 191 | Object obj = cls.newInstance(); |
| 192 | if (serviceClass.isInstance(obj)) { |
| 193 | providers.addElement(obj); |
| 194 | return true; |
| 195 | } |
| 196 | } |
| 197 | catch (ClassNotFoundException e) { } |
| 198 | catch (InstantiationException e) { } |
| 199 | catch (IllegalAccessException e) { } |
| 200 | catch (LinkageError e) { } |
| 201 | } |
| 202 | classNames = null; |
| 203 | } |
| 204 | } |
| 205 | |
| 206 | private static final int START = 0; |
| 207 | private static final int IN_NAME = 1; |
| 208 | private static final int IN_COMMENT = 2; |
| 209 | |
| 210 | private static Enumeration parseConfigFile(URL url) { |
| 211 | try { |
| 212 | InputStream in = url.openStream(); |
| 213 | Reader r; |
| 214 | try { |
| 215 | r = new InputStreamReader(in, "UTF-8"); |
| 216 | } |
| 217 | catch (UnsupportedEncodingException e) { |
| 218 | r = new InputStreamReader(in, "UTF8"); |
| 219 | } |
| 220 | r = new BufferedReader(r); |
| 221 | Vector tokens = new Vector(); |
| 222 | StringBuffer tokenBuf = new StringBuffer(); |
| 223 | int state = START; |
| 224 | for (;;) { |
| 225 | int n = r.read(); |
| 226 | if (n < 0) |
| 227 | break; |
| 228 | char c = (char)n; |
| 229 | switch (c) { |
| 230 | case '\r': |
| 231 | case '\n': |
| 232 | state = START; |
| 233 | break; |
| 234 | case ' ': |
| 235 | case '\t': |
| 236 | break; |
| 237 | case '#': |
| 238 | state = IN_COMMENT; |
| 239 | break; |
| 240 | default: |
| 241 | if (state != IN_COMMENT) { |
| 242 | state = IN_NAME; |
| 243 | tokenBuf.append(c); |
| 244 | } |
| 245 | break; |
| 246 | } |
| 247 | if (tokenBuf.length() != 0 && state != IN_NAME) { |
| 248 | tokens.addElement(tokenBuf.toString()); |
| 249 | tokenBuf.setLength(0); |
| 250 | } |
| 251 | } |
| 252 | if (tokenBuf.length() != 0) |
| 253 | tokens.addElement(tokenBuf.toString()); |
| 254 | return tokens.elements(); |
| 255 | } |
| 256 | catch (IOException e) { |
| 257 | return null; |
| 258 | } |
| 259 | } |
| 260 | } |
| 261 | |
| 262 | } |