Java tutorial
/* * JBoss, Home of Professional Open Source * Copyright 2005, JBoss Inc., and individual contributors as indicated * by the @authors tag. See the copyright.txt in the distribution for a * full listing of individual contributors. * * This is free software; you can redistribute it and/or modify it * under the terms of the GNU Lesser General Public License as * published by the Free Software Foundation; either version 2.1 of * the License, or (at your option) any later version. * * This software is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this software; if not, write to the Free * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA * 02110-1301 USA, or see the FSF site: http://www.fsf.org. */ package ru.runa.notifier.util; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.lang.reflect.Constructor; import java.net.URL; import java.util.Locale; import java.util.Properties; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import com.google.common.base.Charsets; import com.google.common.base.Preconditions; import com.google.common.base.Throwables; /** * Utils. */ public class ClassLoaderUtil { private static final Log log = LogFactory.getLog(ClassLoaderUtil.class); private static final ClassLoader extensionClassLoader = ClassLoaderUtil.class.getClassLoader(); public static Class<?> loadClass(String className, Class<?> callingClass) throws ClassNotFoundException { try { return Thread.currentThread().getContextClassLoader().loadClass(className); } catch (ClassNotFoundException e) { try { return Class.forName(className); } catch (ClassNotFoundException ex) { try { return extensionClassLoader.loadClass(className); } catch (ClassNotFoundException exc) { return callingClass.getClassLoader().loadClass(className); } } } } public static Class<?> loadClass(String className) { try { return loadClass(className, ClassLoaderUtil.class); } catch (ClassNotFoundException e) { throw new RuntimeException("class not found '" + className + "'", e); } } @SuppressWarnings("unchecked") public static <T extends Object> T instantiate(String className) { return (T) instantiate(loadClass(className)); } public static <T extends Object> T instantiate(Class<T> clazz) { try { return clazz.newInstance(); } catch (Exception e) { throw Throwables.propagate(e); } } public static Properties getProperties(String resource, boolean required) { Properties properties = new Properties(); try { InputStream is; if (required) { is = getAsStreamNotNull(resource, ClassLoaderUtil.class); } else { is = getAsStream(resource, ClassLoaderUtil.class); } if (is != null) { properties.load(is); is.close(); } is = getAsStream(Locale.getDefault().getCountry() + "." + resource, ClassLoaderUtil.class); if (is != null) { properties.load(new InputStreamReader(is, Charsets.UTF_8)); is.close(); } } catch (IOException e) { throw new RuntimeException("couldn't load properties file '" + resource + "'", e); } log.debug("Read properties " + resource); log.debug(properties); return properties; } public static URL getAsURL(String resourceName, Class<?> callingClass) { Preconditions.checkNotNull(resourceName, "resourceName"); ClassLoader loader = Thread.currentThread().getContextClassLoader(); URL url = null; while ((loader != null) && (url == null)) { url = loader.getResource(resourceName); loader = loader.getParent(); } if (url == null) { loader = extensionClassLoader; url = loader.getResource(resourceName); } if (url == null) { loader = callingClass.getClassLoader(); if (loader != null) { url = loader.getResource(resourceName); } } if (url == null) { url = callingClass.getResource(resourceName); } if (url == null && resourceName.length() > 0 && resourceName.charAt(0) != '/') { return getAsURL('/' + resourceName, callingClass); } return url; } public static URL getAsURLNotNull(String resourceName, Class<?> callingClass) { URL url = getAsURL(resourceName, callingClass); if (url == null) { throw new RuntimeException("No resource found by '" + resourceName + "'"); } return url; } /** * Get resource as stream. * * @param resourceName * classpath resource name * @param callingClass * package of this class will be inspected for resources * @return resource stream or <code>null</code> */ public static InputStream getAsStream(String resourceName, Class<?> callingClass) { URL url = getAsURL(resourceName, callingClass); try { return url != null ? url.openStream() : null; } catch (IOException e) { return null; } } /** * Get resource as stream. * * @param resourceName * classpath resource name * @param callingClass * package of this class will be inspected for resources * @return resource stream */ public static InputStream getAsStreamNotNull(String resourceName, Class<?> callingClass) { InputStream stream = getAsStream(resourceName, callingClass); if (stream == null) { throw new RuntimeException("No resource found by name '" + resourceName + "'"); } return stream; } public static Object instantiate(String className, Object... params) { try { Class<?> clazz = loadClass(className); Class<?>[] paramType; if (params != null) { paramType = new Class[params.length]; for (int i = 0; i < params.length; ++i) { paramType[i] = params[i].getClass(); } } else { paramType = new Class[0]; params = new Object[0]; } Constructor<?> constructor = null; Constructor<?>[] constructors = clazz.getConstructors(); constrLoop: for (Constructor<?> constr : constructors) { Class<?>[] types = constr.getParameterTypes(); if (types.length != paramType.length) { continue; } for (int i = 0; i < types.length; ++i) { if (!types[i].isAssignableFrom(params[i].getClass())) { continue constrLoop; } } constructor = constr; } if (constructor == null) { constructor = clazz.getConstructor(paramType); } return constructor.newInstance(params); } catch (Exception e) { throw Throwables.propagate(e); } } }