Java tutorial
/* * 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.openjpa.lib.ant; import java.io.File; import java.security.AccessController; import java.util.ArrayList; import java.util.List; import java.util.Map; import org.apache.commons.lang.StringUtils; import org.apache.openjpa.lib.conf.Configuration; import org.apache.openjpa.lib.conf.ConfigurationImpl; import org.apache.openjpa.lib.conf.ConfigurationProvider; import org.apache.openjpa.lib.conf.Configurations; import org.apache.openjpa.lib.conf.ProductDerivations; import org.apache.openjpa.lib.util.J2DoPrivHelper; import org.apache.openjpa.lib.util.Localizer; import org.apache.openjpa.lib.util.MultiClassLoader; import org.apache.tools.ant.AntClassLoader; import org.apache.tools.ant.BuildException; import org.apache.tools.ant.DirectoryScanner; import org.apache.tools.ant.taskdefs.MatchingTask; import org.apache.tools.ant.types.FileSet; import org.apache.tools.ant.types.Path; /** * Ant tasks all have a nested <code><config&rt;</code> tag, which uses * the configuration as a bean-like task. E.g., you can do: * * <code> * <mytask&rt;<br /> * <config connectionUserName="foo"/&rt;<br /> * </mytask&rt; * </code> * * The default configuration for the system will be used if the * <code><config&rt;</code> subtask is excluded. * * @nojavadoc */ public abstract class AbstractTask extends MatchingTask { private static final Localizer _loc = Localizer.forPackage(AbstractTask.class); protected final List<FileSet> fileSets = new ArrayList<FileSet>(); protected boolean haltOnError = true; protected Path classpath = null; protected boolean useParent = false; protected boolean isolate = false; private ConfigurationImpl _conf = null; private AntClassLoader _cl = null; /** * Set whether we want the task to ignore all errors. */ public void setHaltOnError(boolean haltOnError) { this.haltOnError = haltOnError; } /** * Whether we want the ClassLoader to be isolated from * all other ClassLoaders */ public void setIsolate(boolean isolate) { this.isolate = isolate; } /** * Whether we want to delegate to the parent ClassLoader * for resolveing classes. This may "taint" classes. */ public void setUseParentClassloader(boolean useParent) { this.useParent = useParent; } /** * The task configuration. */ public Configuration getConfiguration() { if (_conf == null) { _conf = newConfiguration(); _conf.setDeferResourceLoading(true); } return _conf; } /** * Implement this method to return a configuration object for the * product in use. */ protected abstract ConfigurationImpl newConfiguration(); /** * Perform the task action on the given files. */ protected abstract void executeOn(String[] files) throws Exception; /** * Return the classloader to use. */ protected ClassLoader getClassLoader() { if (_cl != null) return _cl; if (classpath != null) _cl = new AntClassLoader(getProject(), classpath, useParent); else _cl = new AntClassLoader(getProject().getCoreLoader(), getProject(), new Path(getProject()), useParent); _cl.setIsolated(isolate); return _cl; } /** * Helper method to throw a standard exception if the task is not given * any files to execute on. Implementations might call this method as * the first step in {@link #executeOn} to validate that they are given * files to work on. */ protected void assertFiles(String[] files) { if (files.length == 0) throw new BuildException(_loc.get("no-filesets").getMessage()); } public void setClasspath(Path classPath) { createClasspath().append(classPath); } public Path createClasspath() { if (classpath == null) classpath = new Path(getProject()); return classpath.createPath(); } public Object createConfig() { return getConfiguration(); } public void addFileset(FileSet set) { fileSets.add(set); } public void execute() throws BuildException { // if the user didn't supply a conf file, load the default if (_conf == null) _conf = newConfiguration(); ConfigurationProvider cp = null; String propertiesResource = _conf.getPropertiesResource(); if (propertiesResource == null) { cp = ProductDerivations.loadDefaults(getConfigPropertiesResourceLoader()); } else if (_conf.isDeferResourceLoading() && !StringUtils.isEmpty(propertiesResource)) { Map<String, String> result = Configurations.parseConfigResource(propertiesResource); String path = result.get(Configurations.CONFIG_RESOURCE_PATH); String anchor = result.get(Configurations.CONFIG_RESOURCE_ANCHOR); cp = ProductDerivations.load(path, anchor, getConfigPropertiesResourceLoader()); } if (cp != null) { cp.setInto(_conf); } String[] files = getFiles(); try { executeOn(files); } catch (Throwable e) { e.printStackTrace(); if (haltOnError) throw new BuildException(e); } finally { _conf.close(); _conf = null; } } private MultiClassLoader getConfigPropertiesResourceLoader() { MultiClassLoader loader = AccessController.doPrivileged(J2DoPrivHelper.newMultiClassLoaderAction()); loader.addClassLoader(getClassLoader()); loader.addClassLoader(AccessController.doPrivileged(J2DoPrivHelper.getClassLoaderAction(_conf.getClass()))); return loader; } private String[] getFiles() { List<String> files = new ArrayList<String>(); for (FileSet fs : fileSets) { DirectoryScanner ds = fs.getDirectoryScanner(getProject()); String[] dsFiles = ds.getIncludedFiles(); for (int j = 0; j < dsFiles.length; j++) { File f = new File(dsFiles[j]); if (!(AccessController.doPrivileged(J2DoPrivHelper.isFileAction(f))).booleanValue()) f = new File(ds.getBasedir(), dsFiles[j]); files.add(AccessController.doPrivileged(J2DoPrivHelper.getAbsolutePathAction(f))); } } return (String[]) files.toArray(new String[files.size()]); } }