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| org.apache.commons.jelly.tags.core.UseBeanTag |
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| 1 | /* |
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| 2 | * Copyright 2002,2004 The Apache Software Foundation. |
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| 3 | * |
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| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
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| 5 | * you may not use this file except in compliance with the License. |
|
| 6 | * You may obtain a copy of the License at |
|
| 7 | * |
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| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
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| 9 | * |
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| 10 | * Unless required by applicable law or agreed to in writing, software |
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| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
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| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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| 13 | * See the License for the specific language governing permissions and |
|
| 14 | * limitations under the License. |
|
| 15 | */ |
|
| 16 | package org.apache.commons.jelly.tags.core; |
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| 17 | ||
| 18 | import java.lang.reflect.InvocationTargetException; |
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| 19 | import java.util.HashMap; |
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| 20 | import java.util.HashSet; |
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| 21 | import java.util.Iterator; |
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| 22 | import java.util.Map; |
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| 23 | import java.util.Set; |
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| 24 | ||
| 25 | import org.apache.commons.beanutils.BeanUtils; |
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| 26 | import org.apache.commons.beanutils.PropertyUtils; |
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| 27 | import org.apache.commons.jelly.JellyTagException; |
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| 28 | import org.apache.commons.jelly.MapTagSupport; |
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| 29 | import org.apache.commons.jelly.MissingAttributeException; |
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| 30 | import org.apache.commons.jelly.XMLOutput; |
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| 31 | import org.apache.commons.jelly.impl.BeanSource; |
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| 32 | import org.apache.commons.jelly.util.ClassLoaderUtils; |
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| 33 | ||
| 34 | /** |
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| 35 | * A tag which instantiates an instance of the given class |
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| 36 | * and then sets the properties on the bean. |
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| 37 | * The class can be specified via a {@link java.lang.Class} instance or |
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| 38 | * a String which will be used to load the class using either the current |
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| 39 | * thread's context class loader or the class loader used to load this |
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| 40 | * Jelly library. |
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| 41 | * |
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| 42 | * This tag can be used it as follows, |
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| 43 | * <pre> |
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| 44 | * <j:useBean var="person" class="com.acme.Person" name="James" location="${loc}"/> |
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| 45 | * <j:useBean var="order" class="${orderClass}" amount="12" price="123.456"/> |
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| 46 | * </pre> |
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| 47 | * |
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| 48 | * @author <a href="mailto:jstrachan@apache.org">James Strachan</a> |
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| 49 | * @version $Revision: 155420 $ |
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| 50 | */ |
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| 51 | public class UseBeanTag extends MapTagSupport implements BeanSource { |
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| 52 | ||
| 53 | /** the current bean instance */ |
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| 54 | private Object bean; |
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| 55 | ||
| 56 | /** the default class to use if no Class is specified */ |
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| 57 | private Class defaultClass; |
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| 58 | ||
| 59 | /** |
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| 60 | * a Set of Strings of property names to ignore (remove from the |
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| 61 | * Map of attributes before passing to ConvertUtils) |
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| 62 | */ |
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| 63 | private Set ignoreProperties; |
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| 64 | ||
| 65 | /** |
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| 66 | * If this tag finds an attribute in the XML that's not |
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| 67 | * ignored by {@link #ignoreProperties} and isn't a |
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| 68 | * bean property, should it throw an exception? |
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| 69 | * @see #setIgnoreUnknownProperties(boolean) |
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| 70 | */ |
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| 71 | 91 | private boolean ignoreUnknownProperties = false; |
| 72 | ||
| 73 | ||
| 74 | 91 | public UseBeanTag() { |
| 75 | 91 | } |
| 76 | ||
| 77 | 0 | public UseBeanTag(Class defaultClass) { |
| 78 | 0 | this.defaultClass = defaultClass; |
| 79 | 0 | } |
| 80 | ||
| 81 | // BeanSource interface |
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| 82 | //------------------------------------------------------------------------- |
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| 83 | ||
| 84 | /** |
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| 85 | * @return the bean that has just been created |
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| 86 | */ |
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| 87 | public Object getBean() { |
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| 88 | 13 | return bean; |
| 89 | } |
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| 90 | ||
| 91 | ||
| 92 | // Tag interface |
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| 93 | //------------------------------------------------------------------------- |
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| 94 | public void doTag(XMLOutput output) throws JellyTagException { |
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| 95 | 91 | Map attributes = getAttributes(); |
| 96 | 91 | String var = (String) attributes.get( "var" ); |
| 97 | 91 | Object classObject = attributes.get( "class" ); |
| 98 | 91 | addIgnoreProperty("class"); |
| 99 | 91 | addIgnoreProperty("var"); |
| 100 | ||
| 101 | try { |
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| 102 | // this method could return null in derived classes |
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| 103 | 91 | Class theClass = convertToClass(classObject); |
| 104 | ||
| 105 | 91 | bean = newInstance(theClass, attributes, output); |
| 106 | 91 | setBeanProperties(bean, attributes); |
| 107 | ||
| 108 | // invoke body which could result in other properties being set |
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| 109 | 78 | invokeBody(output); |
| 110 | ||
| 111 | 78 | processBean(var, bean); |
| 112 | } |
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| 113 | 0 | catch (ClassNotFoundException e) { |
| 114 | 0 | throw new JellyTagException(e); |
| 115 | 78 | } |
| 116 | 78 | } |
| 117 | ||
| 118 | // Implementation methods |
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| 119 | //------------------------------------------------------------------------- |
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| 120 | ||
| 121 | /** |
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| 122 | * Allow derived classes to programatically set the bean |
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| 123 | */ |
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| 124 | protected void setBean(Object bean) { |
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| 125 | 0 | this.bean = bean; |
| 126 | 0 | } |
| 127 | ||
| 128 | /** |
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| 129 | * Attempts to convert the given object to a Class instance. |
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| 130 | * If the classObject is already a Class it will be returned |
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| 131 | * otherwise it will be converted to a String and loaded |
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| 132 | * using the default class loading mechanism. |
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| 133 | */ |
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| 134 | protected Class convertToClass(Object classObject) |
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| 135 | throws MissingAttributeException, ClassNotFoundException { |
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| 136 | 91 | if (classObject instanceof Class) { |
| 137 | 0 | return (Class) classObject; |
| 138 | } |
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| 139 | 91 | else if ( classObject == null ) { |
| 140 | 0 | Class theClass = getDefaultClass(); |
| 141 | 0 | if (theClass == null) { |
| 142 | 0 | throw new MissingAttributeException("class"); |
| 143 | } |
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| 144 | 0 | return theClass; |
| 145 | } |
|
| 146 | else { |
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| 147 | 91 | String className = classObject.toString(); |
| 148 | 91 | return loadClass(className); |
| 149 | } |
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| 150 | } |
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| 151 | ||
| 152 | /** |
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| 153 | * Loads the given class using the default class loading mechanism |
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| 154 | * which is to try use the current Thread's context class loader first |
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| 155 | * otherise use the class loader which loaded this class. |
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| 156 | */ |
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| 157 | protected Class loadClass(String className) throws ClassNotFoundException { |
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| 158 | 91 | return ClassLoaderUtils.loadClass(className, getClass()); |
| 159 | } |
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| 160 | ||
| 161 | /** |
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| 162 | * Creates a new instance of the given class, which by default will invoke the |
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| 163 | * default constructor. |
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| 164 | * Derived tags could do something different here. |
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| 165 | */ |
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| 166 | protected Object newInstance(Class theClass, Map attributes, XMLOutput output) |
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| 167 | throws JellyTagException { |
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| 168 | try { |
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| 169 | 91 | return theClass.newInstance(); |
| 170 | 0 | } catch (IllegalAccessException e) { |
| 171 | 0 | throw new JellyTagException(e.toString()); |
| 172 | 0 | } catch (InstantiationException e) { |
| 173 | 0 | throw new JellyTagException(e.toString()); |
| 174 | } |
|
| 175 | } |
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| 176 | ||
| 177 | /** |
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| 178 | * Sets the properties on the bean. Derived tags could implement some custom |
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| 179 | * type conversion etc. |
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| 180 | * <p/> |
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| 181 | * This method ignores all property names in the Set returned by {@link #getIgnorePropertySet()}. |
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| 182 | */ |
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| 183 | protected void setBeanProperties(Object bean, Map attributes) throws JellyTagException { |
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| 184 | 91 | Map attrsToUse = new HashMap(attributes); |
| 185 | 91 | attrsToUse.keySet().removeAll(getIgnorePropertySet()); |
| 186 | ||
| 187 | 91 | validateBeanProperties(bean, attrsToUse); |
| 188 | ||
| 189 | try { |
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| 190 | 78 | BeanUtils.populate(bean, attrsToUse); |
| 191 | 0 | } catch (IllegalAccessException e) { |
| 192 | 0 | throw new JellyTagException("could not set the properties of the bean",e); |
| 193 | 0 | } catch (InvocationTargetException e) { |
| 194 | 0 | throw new JellyTagException("could not set the properties of the bean",e); |
| 195 | 78 | } |
| 196 | 78 | } |
| 197 | ||
| 198 | /** |
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| 199 | * If {@link #isIgnoreUnknownProperties()} returns true, make sure that |
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| 200 | * every non-ignored ({@see #addIgnoreProperty(String)}) property |
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| 201 | * matches a writable property on the target bean. |
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| 202 | * @param bean the bean to validate |
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| 203 | * @param attributes the list of properties to validate |
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| 204 | * @throws JellyTagException when a property is not writeable |
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| 205 | */ |
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| 206 | protected void validateBeanProperties(Object bean, Map attributes) throws JellyTagException { |
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| 207 | 91 | if (!isIgnoreUnknownProperties()) { |
| 208 | 78 | for (Iterator i=attributes.keySet().iterator();i.hasNext();) { |
| 209 | 130 | String attrName = (String)i.next(); |
| 210 | 130 | if (! PropertyUtils.isWriteable(bean, attrName)) { |
| 211 | 13 | throw new JellyTagException("No bean property found: " + attrName); |
| 212 | } |
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| 213 | 117 | } |
| 214 | } |
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| 215 | 78 | } |
| 216 | ||
| 217 | /** |
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| 218 | * By default this will export the bean using the given variable if it is defined. |
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| 219 | * This Strategy method allows derived tags to process the beans in different ways |
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| 220 | * such as to register this bean with its parent tag etc. |
|
| 221 | */ |
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| 222 | protected void processBean(String var, Object bean) throws JellyTagException { |
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| 223 | 78 | if (var != null) { |
| 224 | 65 | context.setVariable(var, bean); |
| 225 | 65 | } |
| 226 | else { |
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| 227 | 26 | ArgTag parentArg = (ArgTag)(findAncestorWithClass(ArgTag.class)); |
| 228 | 13 | if(null != parentArg) { |
| 229 | 13 | parentArg.setValue(bean); |
| 230 | } |
|
| 231 | } |
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| 232 | 78 | } |
| 233 | ||
| 234 | /** |
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| 235 | * Allows derived classes to provide a default bean implementation class |
|
| 236 | */ |
|
| 237 | protected Class getDefaultClass() { |
|
| 238 | 0 | return defaultClass; |
| 239 | } |
|
| 240 | ||
| 241 | /** |
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| 242 | * Adds a name to the Set of property names that will be skipped when setting |
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| 243 | * bean properties. In other words, names added here won't be set into the bean |
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| 244 | * if they're present in the attribute Map. |
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| 245 | * @param name |
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| 246 | */ |
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| 247 | protected void addIgnoreProperty(String name) { |
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| 248 | 195 | getIgnorePropertySet().add(name); |
| 249 | 195 | } |
| 250 | ||
| 251 | /** |
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| 252 | * @return the Set of property names that should be ignored when setting the |
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| 253 | * properties of the bean. |
|
| 254 | */ |
|
| 255 | protected Set getIgnorePropertySet() { |
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| 256 | 286 | if (ignoreProperties == null) { |
| 257 | 91 | ignoreProperties = new HashSet(); |
| 258 | } |
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| 259 | ||
| 260 | 286 | return ignoreProperties; |
| 261 | } |
|
| 262 | ||
| 263 | /** |
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| 264 | * @see {@link #setIgnoreUnknownProperties(boolean)} |
|
| 265 | * @return |
|
| 266 | */ |
|
| 267 | public boolean isIgnoreUnknownProperties() { |
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| 268 | 91 | return ignoreUnknownProperties; |
| 269 | } |
|
| 270 | ||
| 271 | /** |
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| 272 | * If this tag finds an attribute in the XML that's not |
|
| 273 | * ignored by {@link #ignoreProperties} and isn't a |
|
| 274 | * bean property, should it throw an exception? |
|
| 275 | * @param ignoreUnknownProperties Sets {@link #ignoreUnknownProperties}. |
|
| 276 | */ |
|
| 277 | public void setIgnoreUnknownProperties(boolean ignoreUnknownProps) { |
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| 278 | 13 | this.ignoreUnknownProperties = ignoreUnknownProps; |
| 279 | 13 | } |
| 280 | } |
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