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Diffstat (limited to 'framework/src/ant/apache-ant-1.9.6/src/main/org/apache/tools/ant/ProjectHelperRepository.java')
| -rw-r--r-- | framework/src/ant/apache-ant-1.9.6/src/main/org/apache/tools/ant/ProjectHelperRepository.java | 337 |
1 files changed, 337 insertions, 0 deletions
diff --git a/framework/src/ant/apache-ant-1.9.6/src/main/org/apache/tools/ant/ProjectHelperRepository.java b/framework/src/ant/apache-ant-1.9.6/src/main/org/apache/tools/ant/ProjectHelperRepository.java new file mode 100644 index 00000000..1dd44124 --- /dev/null +++ b/framework/src/ant/apache-ant-1.9.6/src/main/org/apache/tools/ant/ProjectHelperRepository.java @@ -0,0 +1,337 @@ +/* + * 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 org.apache.tools.ant; + +import java.io.BufferedReader; +import java.io.InputStream; +import java.io.InputStreamReader; +import java.lang.reflect.Constructor; +import java.net.URL; +import java.net.URLConnection; +import java.util.ArrayList; +import java.util.Enumeration; +import java.util.Iterator; +import java.util.List; + +import org.apache.tools.ant.helper.ProjectHelper2; +import org.apache.tools.ant.types.Resource; +import org.apache.tools.ant.util.LoaderUtils; + +/** + * Repository of {@link ProjectHelper} found in the classpath or via + * some System properties. + * + * <p>See the ProjectHelper documentation in the manual.</p> + * + * @since Ant 1.8.0 + */ +public class ProjectHelperRepository { + + private static final String DEBUG_PROJECT_HELPER_REPOSITORY = + "ant.project-helper-repo.debug"; + + // The message log level is not accessible here because everything + // is instanciated statically + private static final boolean DEBUG = + "true".equals(System.getProperty(DEBUG_PROJECT_HELPER_REPOSITORY)); + + private static ProjectHelperRepository instance = + new ProjectHelperRepository(); + + private List<Constructor<? extends ProjectHelper>> helpers = new ArrayList<Constructor<? extends ProjectHelper>>(); + + private static Constructor<ProjectHelper2> PROJECTHELPER2_CONSTRUCTOR; + + static { + try { + PROJECTHELPER2_CONSTRUCTOR = ProjectHelper2.class.getConstructor(); + } catch (Exception e) { + // ProjectHelper2 must be available + throw new RuntimeException(e); + } + } + + public static ProjectHelperRepository getInstance() { + return instance; + } + + private ProjectHelperRepository() { + collectProjectHelpers(); + } + + private void collectProjectHelpers() { + // First, try the system property + Constructor<? extends ProjectHelper> projectHelper = getProjectHelperBySystemProperty(); + registerProjectHelper(projectHelper); + + // A JDK1.3 'service' ( like in JAXP ). That will plug a helper + // automatically if in CLASSPATH, with the right META-INF/services. + try { + ClassLoader classLoader = LoaderUtils.getContextClassLoader(); + if (classLoader != null) { + Enumeration<URL> resources = + classLoader.getResources(ProjectHelper.SERVICE_ID); + while (resources.hasMoreElements()) { + URL resource = resources.nextElement(); + URLConnection conn = resource.openConnection(); + conn.setUseCaches(false); + projectHelper = + getProjectHelperByService(conn.getInputStream()); + registerProjectHelper(projectHelper); + } + } + + InputStream systemResource = + ClassLoader.getSystemResourceAsStream(ProjectHelper.SERVICE_ID); + if (systemResource != null) { + projectHelper = getProjectHelperByService(systemResource); + registerProjectHelper(projectHelper); + } + } catch (Exception e) { + System.err.println("Unable to load ProjectHelper from service " + + ProjectHelper.SERVICE_ID + " (" + + e.getClass().getName() + + ": " + e.getMessage() + ")"); + if (DEBUG) { + e.printStackTrace(System.err); + } + } + } + + /** + * Register the specified project helper into the repository. + * <p> + * The helper will be added after all the already registered helpers, but + * before the default one (ProjectHelper2) + * + * @param helperClassName + * the fully qualified name of the helper + * @throws BuildException + * if the class cannot be loaded or if there is no constructor + * with no argument + * @since Ant 1.8.2 + */ + public void registerProjectHelper(String helperClassName) + throws BuildException { + registerProjectHelper(getHelperConstructor(helperClassName)); + } + + /** + * Register the specified project helper into the repository. + * <p> + * The helper will be added after all the already registered helpers, but + * before the default one (ProjectHelper2) + * + * @param helperClass + * the class of the helper + * @throws BuildException + * if there is no constructor with no argument + * @since Ant 1.8.2 + */ + public void registerProjectHelper(Class<? extends ProjectHelper> helperClass) throws BuildException { + try { + registerProjectHelper(helperClass.getConstructor()); + } catch (NoSuchMethodException e) { + throw new BuildException("Couldn't find no-arg constructor in " + + helperClass.getName()); + } + } + + private void registerProjectHelper(Constructor<? extends ProjectHelper> helperConstructor) { + if (helperConstructor == null) { + return; + } + if (DEBUG) { + System.out.println("ProjectHelper " + + helperConstructor.getClass().getName() + " registered."); + } + helpers.add(helperConstructor); + } + + private Constructor<? extends ProjectHelper> getProjectHelperBySystemProperty() { + String helperClass = System.getProperty(ProjectHelper.HELPER_PROPERTY); + try { + if (helperClass != null) { + return getHelperConstructor(helperClass); + } + } catch (SecurityException e) { + System.err.println("Unable to load ProjectHelper class \"" + + helperClass + " specified in system property " + + ProjectHelper.HELPER_PROPERTY + " (" + + e.getMessage() + ")"); + if (DEBUG) { + e.printStackTrace(System.err); + } + } + return null; + } + + private Constructor<? extends ProjectHelper> getProjectHelperByService(InputStream is) { + try { + // This code is needed by EBCDIC and other strange systems. + // It's a fix for bugs reported in xerces + InputStreamReader isr; + try { + isr = new InputStreamReader(is, "UTF-8"); + } catch (java.io.UnsupportedEncodingException e) { + isr = new InputStreamReader(is); + } + BufferedReader rd = new BufferedReader(isr); + + String helperClassName = rd.readLine(); + rd.close(); + + if (helperClassName != null && !"".equals(helperClassName)) { + return getHelperConstructor(helperClassName); + } + } catch (Exception e) { + System.out.println("Unable to load ProjectHelper from service " + + ProjectHelper.SERVICE_ID + " (" + e.getMessage() + ")"); + if (DEBUG) { + e.printStackTrace(System.err); + } + } + return null; + } + + /** + * Get the constructor with not argument of an helper from its class name. + * It'll first try the thread class loader, then Class.forName() will load + * from the same loader that loaded this class. + * + * @param helperClass + * The name of the class to create an instance of. Must not be + * <code>null</code>. + * + * @return the constructor of the specified class. + * + * @exception BuildException + * if the class cannot be found or if a constructor with no + * argument cannot be found. + */ + private Constructor<? extends ProjectHelper> getHelperConstructor(String helperClass) throws BuildException { + ClassLoader classLoader = LoaderUtils.getContextClassLoader(); + try { + Class<?> clazz = null; + if (classLoader != null) { + try { + clazz = classLoader.loadClass(helperClass); + } catch (ClassNotFoundException ex) { + // try next method + } + } + if (clazz == null) { + clazz = Class.forName(helperClass); + } + return clazz.asSubclass(ProjectHelper.class).getConstructor(); + } catch (Exception e) { + throw new BuildException(e); + } + } + + /** + * Get the helper that will be able to parse the specified build file. The helper + * will be chosen among the ones found in the classpath + * + * @return the first ProjectHelper that fit the requirement (never <code>null</code>). + */ + public ProjectHelper getProjectHelperForBuildFile(Resource buildFile) throws BuildException { + for (Iterator<ProjectHelper> it = getHelpers(); it.hasNext();) { + ProjectHelper helper = it.next(); + if (helper.canParseBuildFile(buildFile)) { + if (DEBUG) { + System.out.println("ProjectHelper " + + helper.getClass().getName() + + " selected for the build file " + + buildFile); + } + return helper; + } + } + throw new RuntimeException("BUG: at least the ProjectHelper2 should " + + "have supported the file " + buildFile); + } + + /** + * Get the helper that will be able to parse the specified antlib. The helper + * will be chosen among the ones found in the classpath + * + * @return the first ProjectHelper that fit the requirement (never <code>null</code>). + */ + public ProjectHelper getProjectHelperForAntlib(Resource antlib) throws BuildException { + for (Iterator<ProjectHelper> it = getHelpers(); it.hasNext();) { + ProjectHelper helper = it.next(); + if (helper.canParseAntlibDescriptor(antlib)) { + if (DEBUG) { + System.out.println("ProjectHelper " + + helper.getClass().getName() + + " selected for the antlib " + + antlib); + } + return helper; + } + } + throw new RuntimeException("BUG: at least the ProjectHelper2 should " + + "have supported the file " + antlib); + } + + /** + * Get an iterator on the list of project helpers configured. The iterator + * will always return at least one element as there will always be the + * default project helper configured. + * + * @return an iterator of {@link ProjectHelper} + */ + public Iterator<ProjectHelper> getHelpers() { + return new ConstructingIterator(helpers.iterator()); + } + + private static class ConstructingIterator implements Iterator<ProjectHelper> { + private final Iterator<Constructor<? extends ProjectHelper>> nested; + private boolean empty = false; + + ConstructingIterator(Iterator<Constructor<? extends ProjectHelper>> nested) { + this.nested = nested; + } + + public boolean hasNext() { + return nested.hasNext() || !empty; + } + + public ProjectHelper next() { + Constructor<? extends ProjectHelper> c; + if (nested.hasNext()) { + c = nested.next(); + } else { + // last but not least, ant default project helper + empty = true; + c = PROJECTHELPER2_CONSTRUCTOR; + } + try { + return c.newInstance(); + } catch (Exception e) { + throw new BuildException("Failed to invoke no-arg constructor" + + " on " + c.getName()); + } + } + + public void remove() { + throw new UnsupportedOperationException("remove is not supported"); + } + } +} |