Java tutorial
/* * Licensed 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 net.sf.morph2.context.contexts; import java.util.Arrays; import java.util.Collection; import java.util.Iterator; import java.util.Locale; import java.util.Map; import java.util.Set; import net.sf.composite.util.ObjectUtils; import net.sf.morph2.Defaults; import net.sf.morph2.context.Context; import net.sf.morph2.context.ContextException; import net.sf.morph2.context.DecoratedContext; import net.sf.morph2.context.support.ContextMapBridge; import net.sf.morph2.lang.Language; import net.sf.morph2.transform.Converter; import net.sf.morph2.util.ContainerUtils; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; /** * <p> * Convenient base class for Contexts. Validates arguments and takes care of * logging and exception handling. Also implements the {@link java.util.Map} * interface. * </p> * * <p> * As a Map, this class only supports non-null Strings for keys (i.e. - calling * <code>Map.put(new Object(), new Object())</code> will throw a * {@link net.sf.morph2.context.ContextException}). * </p> * * @author Matt Sgarlata * @since Nov 19, 2004 */ public abstract class BaseContext implements Context, Map, DecoratedContext { private static final ContextMapBridge DEFAULT_CONTEXT_MAP_BRIDGE = new ContextMapBridge(); private transient Log log = LogFactory.getLog(getClass()); private ContextMapBridge contextMapBridge; private Converter converter; private Language language; /** * Create a new BaseContext. */ public BaseContext() { super(); setContextMapBridge(DEFAULT_CONTEXT_MAP_BRIDGE); setConverter(Defaults.createConverter()); setLanguage(Defaults.createLanguage()); } /** * Implement getPropertyNames() * @return String[] of property names * @throws Exception if errors occur */ protected abstract String[] getPropertyNamesImpl() throws Exception; /** * Implement <code>get(propertyName)</code>. * @param propertyName to get * @return Object value * @throws Exception in case of errors */ protected abstract Object getImpl(String propertyName) throws Exception; /** * Implement <code>set(propertyName, propertyValue)</code>. * @param propertyName to set * @param propertyValue to set * @throws Exception in case of errors */ protected abstract void setImpl(String propertyName, Object propertyValue) throws Exception; /** * {@inheritDoc} */ public final String[] getPropertyNames() throws ContextException { try { // retrieve the property names String[] cachedPropertyNames = getPropertyNamesImpl(); Set propertyNames = ContainerUtils.createOrderedSet(); if (!ObjectUtils.isEmpty(cachedPropertyNames)) { propertyNames.addAll(Arrays.asList(cachedPropertyNames)); } // // include the propertyNames property // int size = cachedPropertyNames == null ? 0 : cachedPropertyNames.length; // Set propertyNames = new ContainerUtils.createOrderedSet(size+1); // propertyNames.add(PROPERTY_NAMES_PROPERTY); // if (!ObjectUtils.isEmpty(cachedPropertyNames)) { // propertyNames.addAll(Arrays.asList(cachedPropertyNames)); // } // loop through and remove properties that aren't valid according to // the language Iterator iterator = propertyNames.iterator(); while (iterator.hasNext()) { String propertyName = (String) iterator.next(); if (!getLanguage().isProperty(propertyName)) { iterator.remove(); } } return (String[]) propertyNames.toArray(new String[propertyNames.size()]); } catch (ContextException e) { throw e; } catch (Exception e) { throw new ContextException("Unable to retrieve property names", e); } } /** * {@inheritDoc} */ public final Object get(String expression) throws ContextException { if (getLanguage().isProperty(expression)) { // make sure a property name is specified if (ObjectUtils.isEmpty(expression)) { throw new ContextException("You must specify a propertyName to retrieve"); } // make sure the propertyName is a valid property String[] propertyNames = getPropertyNames(); if (!(ContainerUtils.contains(propertyNames, expression))) { return null; } try { // Object returnVal = getImpl(expression); // // exposes propertyNames as a property of the Map, if desired // if (returnVal == null && // PROPERTY_NAMES_PROPERTY.equals(expression)) { // return getPropertyNames(); // } return getImpl(expression); } catch (ContextException e) { throw e; } catch (Exception e) { throw new ContextException("Could not retrieve property '" + expression + "' from this context", e); } } return getLanguage().get(this, expression); } /** * {@inheritDoc} */ public final void set(String expression, Object value) throws ContextException { if (getLanguage().isProperty(expression)) { // make sure a property name is specified if (ObjectUtils.isEmpty(expression)) { throw new ContextException("You must specify an expression to set"); } // // make sure the propertyName is a valid property // String[] propertyNames = getPropertyNames(); // if (!(MorphUtils.contains(propertyNames, expression))) { // return null; // } try { setImpl(expression, value); } catch (ContextException e) { throw e; } catch (Exception e) { throw new ContextException("Could not set property '" + expression + "' in context " + ObjectUtils.getObjectDescription(this), e); } } else { getLanguage().set(this, expression, value); } } /** * {@inheritDoc} */ public final Object get(String expression, Class destinationClass) throws ContextException { return get(expression, destinationClass, Locale.getDefault()); } /** * {@inheritDoc} */ public final Object get(String expression, Class destinationClass, Locale locale) throws ContextException { try { Object object = get(expression); return getConverter().convert(destinationClass, object, locale); } catch (Exception e) { throw new ContextException("Unable to retrieve value for expression '" + expression + "' as destination " + ObjectUtils.getObjectDescription(destinationClass), e); } } /** * {@inheritDoc} */ public final Object get(String expression, Locale locale, Class destinationClass) throws ContextException { return get(expression, destinationClass, locale); } /** * {@inheritDoc} */ public final void set(String expression, Object value, Locale locale) throws ContextException { if (ObjectUtils.isEmpty(expression)) { throw new ContextException("You must specify a propertyName to set"); } try { setImpl(expression, value); } catch (ContextException e) { throw e; } catch (Exception e) { throw new ContextException( "Could not set '" + expression + "' to " + ObjectUtils.getObjectDescription(value), e); } } /** * {@inheritDoc} */ public void clear() { getContextMapBridge().clear(this); } /** * The implementation of this method has O(n) time complexity. * @see java.util.Map#containsKey(java.lang.Object) */ public boolean containsKey(Object key) { return getContextMapBridge().containsKey(this, key); } /** * {@inheritDoc} */ public boolean containsValue(Object value) { return getContextMapBridge().containsValue(this, value); } /** * {@inheritDoc} */ public Set entrySet() { return getContextMapBridge().entrySet(this); } /** * {@inheritDoc} */ public Object get(Object key) { return getContextMapBridge().get(this, key); } /** * {@inheritDoc} */ public boolean isEmpty() { return getContextMapBridge().isEmpty(this); } /** * {@inheritDoc} */ public Set keySet() { return getContextMapBridge().keySet(this); } /** * {@inheritDoc} */ public Object put(Object key, Object value) { return getContextMapBridge().put(this, key, value); } /** * {@inheritDoc} */ public void putAll(Map t) { getContextMapBridge().putAll(this, t); } /** * {@inheritDoc} */ public Object remove(Object key) { return getContextMapBridge().remove(this, key); } /** * {@inheritDoc} */ public int size() { return getContextMapBridge().size(this); } /** * {@inheritDoc} */ public Collection values() { return getContextMapBridge().values(this); } /** * Get the converter. * @return Returns the converter. */ public Converter getConverter() { if (converter == null) { setConverter(Defaults.createConverter()); } return converter; } /** * Set the converter. * @param converter The converter to set. */ public void setConverter(Converter converter) { this.converter = converter; } /** * Get the Language. * @return Returns the language. */ public Language getLanguage() { if (language == null) { setLanguage(Defaults.createLanguage()); } return language; } /** * Set the Language. * @param language The language to set. */ public void setLanguage(Language language) { this.language = language; } /** * Set the ContextMapBridge. * @param contextMapBridge to set */ public void setContextMapBridge(ContextMapBridge contextMapBridge) { this.contextMapBridge = contextMapBridge; } /** * Get the ContextMapBridge. * @return ContextMapBridge */ public ContextMapBridge getContextMapBridge() { return contextMapBridge == null ? DEFAULT_CONTEXT_MAP_BRIDGE : contextMapBridge; } /** * Get the log. * @return Log */ protected Log getLog() { return log; } /** * Set the Log. * @param log to set */ protected void setLog(Log log) { this.log = log; } // this causes an infinite loop // public String toString() { // return (new HashMap(this)).toString(); // } }