| /* |
| * $Id$ |
| * |
| * Copyright 2006 The Apache Software Foundation. |
| * |
| * 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 org.apache.struts2.util; |
| |
| import java.util.Map; |
| |
| import ognl.DefaultTypeConverter; |
| |
| /** |
| * <!-- START SNIPPET: javadoc --> |
| * |
| * Base class for type converters used in Struts. This class provides two abstract methods that are used to convert |
| * both to and from strings -- the critical functionality that is core to Struts's type coversion system. |
| * |
| * <p/> Type converters do not have to use this class. It is merely a helper base class, although it is recommended that |
| * you use this class as it provides the common type conversion contract required for all web-based type conversion. |
| * |
| * <p/> There's a hook (fall back method) called <code>performFallbackConversion</code> of which |
| * could be used to perform some fallback conversion if <code>convertValue</code> method of this |
| * failed. By default it just ask its super class (Ognl's DefaultTypeConverter) to do the conversion. |
| * |
| * <p/> To allow the framework to recognize that a conversion error has occurred, throw an XWorkException or |
| * preferable a TypeConversionException. |
| * |
| * <!-- END SNIPPET: javadoc --> |
| * |
| */ |
| public abstract class StrutsTypeConverter extends DefaultTypeConverter { |
| public Object convertValue(Map context, Object o, Class toClass) { |
| if (toClass.equals(String.class)) { |
| return convertToString(context, o); |
| } else if (o instanceof String[]) { |
| return convertFromString(context, (String[]) o, toClass); |
| } else if (o instanceof String) { |
| return convertFromString(context, new String[]{(String) o}, toClass); |
| } else { |
| return performFallbackConversion(context, o, toClass); |
| } |
| } |
| |
| /** |
| * Hook to perform a fallback conversion if every default options failed. By default |
| * this will ask Ognl's DefaultTypeConverter (of which this class extends) to |
| * perform the conversion. |
| * |
| * @param context |
| * @param o |
| * @param toClass |
| * @return The fallback conversion |
| */ |
| protected Object performFallbackConversion(Map context, Object o, Class toClass) { |
| return super.convertValue(context, o, toClass); |
| } |
| |
| |
| /** |
| * Converts one or more String values to the specified class. |
| * |
| * @param context the action context |
| * @param values the String values to be converted, such as those submitted from an HTML form |
| * @param toClass the class to convert to |
| * @return the converted object |
| */ |
| public abstract Object convertFromString(Map context, String[] values, Class toClass); |
| |
| /** |
| * Converts the specified object to a String. |
| * |
| * @param context the action context |
| * @param o the object to be converted |
| * @return the converted String |
| */ |
| public abstract String convertToString(Map context, Object o); |
| } |