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 com.googlecode.jsfFlex.myFaces; import org.apache.commons.el.Coercions; import org.apache.commons.el.Logger; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import javax.faces.FacesException; import javax.servlet.jsp.el.ELException; import java.io.InputStream; import java.io.IOException; import java.lang.reflect.Array; import java.util.*; /** * Due to need of certain classes from the MyFaces project for the builder-plugin, this package<br> * will contain classes from MyFaces.<br> * * @author Manfred Geiler (latest modification by $Author: skitching $) * @author Anton Koinov * @version $Revision: 711306 $ $Date: 2008-11-04 09:49:37 -0700 (Tue, 04 Nov 2008) $ */ public final class ClassUtils { //~ Static fields/initializers ----------------------------------------------------------------- private static final Log log = LogFactory.getLog(ClassUtils.class); private static final Logger COERCION_LOGGER = new Logger(System.out); public static final Class BOOLEAN_ARRAY_CLASS = boolean[].class; public static final Class BYTE_ARRAY_CLASS = byte[].class; public static final Class CHAR_ARRAY_CLASS = char[].class; public static final Class SHORT_ARRAY_CLASS = short[].class; public static final Class INT_ARRAY_CLASS = int[].class; public static final Class LONG_ARRAY_CLASS = long[].class; public static final Class FLOAT_ARRAY_CLASS = float[].class; public static final Class DOUBLE_ARRAY_CLASS = double[].class; public static final Class OBJECT_ARRAY_CLASS = Object[].class; public static final Class BOOLEAN_OBJECT_ARRAY_CLASS = Boolean[].class; public static final Class BYTE_OBJECT_ARRAY_CLASS = Byte[].class; public static final Class CHARACTER_OBJECT_ARRAY_CLASS = Character[].class; public static final Class SHORT_OBJECT_ARRAY_CLASS = Short[].class; public static final Class INTEGER_OBJECT_ARRAY_CLASS = Integer[].class; public static final Class LONG_OBJECT_ARRAY_CLASS = Long[].class; public static final Class FLOAT_OBJECT_ARRAY_CLASS = Float[].class; public static final Class DOUBLE_OBJECT_ARRAY_CLASS = Double[].class; public static final Class STRING_OBJECT_ARRAY_CLASS = String[].class; public static final Map COMMON_TYPES = new HashMap(64); static { COMMON_TYPES.put("byte", Byte.TYPE); COMMON_TYPES.put("char", Character.TYPE); COMMON_TYPES.put("double", Double.TYPE); COMMON_TYPES.put("float", Float.TYPE); COMMON_TYPES.put("int", Integer.TYPE); COMMON_TYPES.put("long", Long.TYPE); COMMON_TYPES.put("short", Short.TYPE); COMMON_TYPES.put("boolean", Boolean.TYPE); COMMON_TYPES.put("void", Void.TYPE); COMMON_TYPES.put("java.lang.Object", Object.class); COMMON_TYPES.put("java.lang.Boolean", Boolean.class); COMMON_TYPES.put("java.lang.Byte", Byte.class); COMMON_TYPES.put("java.lang.Character", Character.class); COMMON_TYPES.put("java.lang.Short", Short.class); COMMON_TYPES.put("java.lang.Integer", Integer.class); COMMON_TYPES.put("java.lang.Long", Long.class); COMMON_TYPES.put("java.lang.Float", Float.class); COMMON_TYPES.put("java.lang.Double", Double.class); COMMON_TYPES.put("java.lang.String", String.class); COMMON_TYPES.put("byte[]", BYTE_ARRAY_CLASS); COMMON_TYPES.put("char[]", CHAR_ARRAY_CLASS); COMMON_TYPES.put("double[]", DOUBLE_ARRAY_CLASS); COMMON_TYPES.put("float[]", FLOAT_ARRAY_CLASS); COMMON_TYPES.put("int[]", INT_ARRAY_CLASS); COMMON_TYPES.put("long[]", LONG_ARRAY_CLASS); COMMON_TYPES.put("short[]", SHORT_ARRAY_CLASS); COMMON_TYPES.put("boolean[]", BOOLEAN_ARRAY_CLASS); COMMON_TYPES.put("java.lang.Object[]", OBJECT_ARRAY_CLASS); COMMON_TYPES.put("java.lang.Boolean[]", BOOLEAN_OBJECT_ARRAY_CLASS); COMMON_TYPES.put("java.lang.Byte[]", BYTE_OBJECT_ARRAY_CLASS); COMMON_TYPES.put("java.lang.Character[]", CHARACTER_OBJECT_ARRAY_CLASS); COMMON_TYPES.put("java.lang.Short[]", SHORT_OBJECT_ARRAY_CLASS); COMMON_TYPES.put("java.lang.Integer[]", INTEGER_OBJECT_ARRAY_CLASS); COMMON_TYPES.put("java.lang.Long[]", LONG_OBJECT_ARRAY_CLASS); COMMON_TYPES.put("java.lang.Float[]", FLOAT_OBJECT_ARRAY_CLASS); COMMON_TYPES.put("java.lang.Double[]", DOUBLE_OBJECT_ARRAY_CLASS); COMMON_TYPES.put("java.lang.String[]", STRING_OBJECT_ARRAY_CLASS); // array of void is not a valid type } /** utility class, do not instantiate */ private ClassUtils() { // utility class, disable instantiation } //~ Methods ------------------------------------------------------------------------------------ /** * Tries a Class.loadClass with the context class loader of the current thread first and * automatically falls back to the ClassUtils class loader (i.e. the loader of the * myfaces.jar lib) if necessary. * * @param type fully qualified name of a non-primitive non-array class * @return the corresponding Class * @throws NullPointerException if type is null * @throws ClassNotFoundException */ public static Class classForName(String type) throws ClassNotFoundException { if (type == null) throw new NullPointerException("type"); try { // Try WebApp ClassLoader first return Class.forName(type, false, // do not initialize for faster startup Thread.currentThread().getContextClassLoader()); } catch (ClassNotFoundException ignore) { // fallback: Try ClassLoader for ClassUtils (i.e. the myfaces.jar lib) return Class.forName(type, false, // do not initialize for faster startup ClassUtils.class.getClassLoader()); } } /** * Same as {@link #classForName(String)}, but throws a RuntimeException * (FacesException) instead of a ClassNotFoundException. * * @return the corresponding Class * @throws NullPointerException if type is null * @throws FacesException if class not found */ public static Class simpleClassForName(String type) { try { return classForName(type); } catch (ClassNotFoundException e) { log.error("Class " + type + " not found", e); throw new FacesException(e); } } /** * Similar as {@link #classForName(String)}, but also supports primitive types * and arrays as specified for the JavaType element in the JavaServer Faces Config DTD. * * @param type fully qualified class name or name of a primitive type, both optionally * followed by "[]" to indicate an array type * @return the corresponding Class * @throws NullPointerException if type is null * @throws ClassNotFoundException */ public static Class javaTypeToClass(String type) throws ClassNotFoundException { if (type == null) throw new NullPointerException("type"); // try common types and arrays of common types first Class clazz = (Class) COMMON_TYPES.get(type); if (clazz != null) { return clazz; } int len = type.length(); if (len > 2 && type.charAt(len - 1) == ']' && type.charAt(len - 2) == '[') { String componentType = type.substring(0, len - 2); Class componentTypeClass = classForName(componentType); return Array.newInstance(componentTypeClass, 0).getClass(); } else { return classForName(type); } } /** * Same as {@link #javaTypeToClass(String)}, but throws a RuntimeException * (FacesException) instead of a ClassNotFoundException. * * @return the corresponding Class * @throws NullPointerException if type is null * @throws FacesException if class not found */ public static Class simpleJavaTypeToClass(String type) { try { return javaTypeToClass(type); } catch (ClassNotFoundException e) { log.error("Class " + type + " not found", e); throw new FacesException(e); } } public static InputStream getResourceAsStream(String resource) { InputStream stream = Thread.currentThread().getContextClassLoader().getResourceAsStream(resource); if (stream == null) { // fallback stream = ClassUtils.class.getClassLoader().getResourceAsStream(resource); } return stream; } /** * @param resource Name of resource(s) to find in classpath * @param defaultObject The default object to use to determine the class loader (if none associated with current thread.) * @return Iterator over URL Objects */ public static Iterator getResources(String resource, Object defaultObject) { try { Enumeration resources = getCurrentLoader(defaultObject).getResources(resource); List lst = new ArrayList(); while (resources.hasMoreElements()) { lst.add(resources.nextElement()); } return lst.iterator(); } catch (IOException e) { log.error(e.getMessage(), e); throw new FacesException(e); } } public static Object newInstance(String type) throws FacesException { if (type == null) return null; return newInstance(simpleClassForName(type)); } public static Object newInstance(String type, Class expectedType) throws FacesException { return newInstance(type, expectedType == null ? null : new Class[] { expectedType }); } public static Object newInstance(String type, Class[] expectedTypes) { if (type == null) return null; Class clazzForName = simpleClassForName(type); if (expectedTypes != null) { for (int i = 0, size = expectedTypes.length; i < size; i++) { if (!expectedTypes[i].isAssignableFrom(clazzForName)) { throw new FacesException( "'" + type + "' does not implement expected type '" + expectedTypes[i] + "'"); } } } return newInstance(clazzForName); } public static Object newInstance(Class clazz) throws FacesException { try { return clazz.newInstance(); } catch (NoClassDefFoundError e) { log.error("Class : " + clazz.getName() + " not found.", e); throw new FacesException(e); } catch (InstantiationException e) { log.error(e.getMessage(), e); throw new FacesException(e); } catch (IllegalAccessException e) { log.error(e.getMessage(), e); throw new FacesException(e); } } public static Object convertToType(Object value, Class desiredClass) { if (value == null) return null; try { // Use coersion implemented by JSP EL for consistency with EL // expressions. Additionally, it caches some of the coersions. return Coercions.coerce(value, desiredClass, COERCION_LOGGER); } catch (ELException e) { String message = "Cannot coerce " + value.getClass().getName() + " to " + desiredClass.getName(); log.error(message, e); throw new FacesException(message, e); } } /** * Gets the ClassLoader associated with the current thread. Returns the class loader associated with * the specified default object if no context loader is associated with the current thread. * * @param defaultObject The default object to use to determine the class loader (if none associated with current thread.) * @return ClassLoader */ protected static ClassLoader getCurrentLoader(Object defaultObject) { ClassLoader loader = Thread.currentThread().getContextClassLoader(); if (loader == null) { loader = defaultObject.getClass().getClassLoader(); } return loader; } }