LookupUtil


1   /**
2    * Licensed under the Artistic License; you may not use this file
3    * except in compliance with the License.
4    * You may obtain a copy of the License at
5    *
6    *      http://displaytag.sourceforge.net/license.html
7    *
8    * THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR
9    * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
10   * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
11   */
12  package org.displaytag.util;
13  
14  import java.lang.reflect.InvocationTargetException  ;
15  import java.util.List  ;
16  import java.util.Map  ;
17  
18  import javax.servlet.jsp.PageContext  ;
19  
20  import org.apache.commons.beanutils.NestedNullException;
21  import org.apache.commons.beanutils.PropertyUtils;
22  import org.apache.commons.lang.StringUtils;
23  import org.apache.commons.lang.Validate;
24  import org.apache.commons.logging.Log;
25  import org.apache.commons.logging.LogFactory;
26  import org.displaytag.exception.ObjectLookupException;
27  
28  
29  /**
30   * Utility class with methods for object and properties retrieving.
31   * @author Fabrizio Giustina
32   * @version $Id: LookupUtil.java 985 2005-12-31 13:56:12Z fgiust $
33   */
34  public final class LookupUtil
35  {
36  
37      /**
38       * logger.
39       */
40      private static Log log = LogFactory.getLog(LookupUtil.class);
41  
42      /**
43       * don't instantiate a LookupUtil.
44       */
45      private LookupUtil()
46      {
47          // unused
48      }
49  
50      /**
51       * Read an object from the pagecontext with the specified scope and eventually lookup a property in it.
52       * @param pageContext PageContext
53       * @param beanAndPropertyName String expression with bean name and attributes
54       * @param scope One of the following values:
55       * <ul>
56       * <li>PageContext.PAGE_SCOPE</li>
57       * <li>PageContext.REQUEST_SCOPE</li>
58       * <li>PageContext.SESSION_SCOPE</li>
59       * <li>PageContext.APPLICATION_SCOPE</li>
60       * </ul>
61       * @return Object
62       * @throws ObjectLookupException for errors while retrieving a property in the bean
63       */
64      public static Object   getBeanValue(PageContext   pageContext, String   beanAndPropertyName, int scope)
65          throws ObjectLookupException
66      {
67  
68          if (beanAndPropertyName.indexOf('.') != -1)
69          {
70              // complex: property from a bean
71              String   objectName = StringUtils.substringBefore(beanAndPropertyName, ".");
72              String   beanProperty = StringUtils.substringAfter(beanAndPropertyName, ".");
73              Object   beanObject;
74  
75              if (log.isDebugEnabled())
76              {
77                  log.debug("getBeanValue - bean: {" + objectName + "}, property: {" + beanProperty + "}");
78              }
79  
80              // get the bean
81              beanObject = pageContext.getAttribute(objectName, scope);
82  
83              // if null return
84              if (beanObject == null)
85              {
86                  return null;
87              }
88  
89              // go get the property
90              return getBeanProperty(beanObject, beanProperty);
91  
92          }
93  
94          // simple, only the javabean
95          if (log.isDebugEnabled())
96          {
97              log.debug("getBeanValue - bean: {" + beanAndPropertyName + "}");
98          }
99  
100         return pageContext.getAttribute(beanAndPropertyName, scope);
101     }
102 
103     /**
104      * <p>
105      * Returns the value of a property in the given bean.
106      * </p>
107      * <p>
108      * Handle <code>NestedNullException</code> returning nulls and other exceptions returning
109      * <code>ObjectLookupException</code>.
110      * </p>
111      * @param bean javabean
112      * @param name name of the property to read from the javabean
113      * @return Object
114      * @throws ObjectLookupException for errors while retrieving a property in the bean
115      */
116     public static Object   getBeanProperty(Object   bean, String   name) throws ObjectLookupException
117     {
118 
119         Validate.notNull(bean, "No bean specified");
120         Validate.notNull(name, "No name specified");
121 
122         if (log.isDebugEnabled())
123         {
124             log.debug("getProperty [" + name + "] on bean " + bean);
125         }
126 
127         try
128         {
129             return getProperty(bean, name);
130         }
131         catch (IllegalAccessException   e)
132         {
133             throw new ObjectLookupException(LookupUtil.class, bean, name, e);
134         }
135         catch (InvocationTargetException   e)
136         {
137             throw new ObjectLookupException(LookupUtil.class, bean, name, e);
138         }
139         catch (NoSuchMethodException   e)
140         {
141             throw new ObjectLookupException(LookupUtil.class, bean, name, e);
142         }
143         catch (NestedNullException nne)
144         {
145             // don't throw exceptions for nulls
146             return null;
147         }
148         catch (IllegalArgumentException   e)
149         {
150             // don't throw exceptions for nulls; the bean and name have already been checked; this is being thrown when
151             // the bean property value is itself null.
152             log
153                 .debug(
154                     "Caught IllegalArgumentException from beanutils while looking up " + name + " in bean " + bean,
155                     e);
156             return null;
157         }
158     }
159 
160     /**
161      * Return the value of the (possibly nested) property of the specified name, for the specified bean, with no type
162      * conversions.
163      * @param bean Bean whose property is to be extracted
164      * @param name Possibly nested name of the property to be extracted
165      * @return Object
166      * @throws NoSuchMethodException
167      * @throws InvocationTargetException
168      * @throws IllegalAccessException
169      * @throws BeanPropertyLookupException in caso di errori nella lettura di propriet� del bean
170      */
171     public static Object   getProperty(Object   bean, String   name) throws IllegalAccessException  ,
172         InvocationTargetException  , NoSuchMethodException  
173     {
174         if (log.isDebugEnabled())
175         {
176             log.debug("getProperty [" + name + "] on bean " + bean);
177         }
178 
179         Validate.notNull(bean, "No bean specified");
180         Validate.notNull(name, "No name specified");
181 
182         Object   evalBean = bean;
183         String   evalName = name;
184 
185         if (evalBean == null)
186         {
187             throw new IllegalArgumentException  ("No bean specified");
188         }
189         if (evalName == null)
190         {
191             throw new IllegalArgumentException  ("No name specified");
192         }
193 
194         int indexOfINDEXEDDELIM = -1;
195         int indexOfMAPPEDDELIM = -1;
196         int indexOfMAPPEDDELIM2 = -1;
197         int indexOfNESTEDDELIM = -1;
198         while (true)
199         {
200 
201             indexOfNESTEDDELIM = evalName.indexOf(PropertyUtils.NESTED_DELIM);
202             indexOfMAPPEDDELIM = evalName.indexOf(PropertyUtils.MAPPED_DELIM);
203             indexOfMAPPEDDELIM2 = evalName.indexOf(PropertyUtils.MAPPED_DELIM2);
204             if (indexOfMAPPEDDELIM2 >= 0
205                 && indexOfMAPPEDDELIM >= 0
206                 && (indexOfNESTEDDELIM < 0 || indexOfNESTEDDELIM > indexOfMAPPEDDELIM))
207             {
208                 indexOfNESTEDDELIM = evalName.indexOf(PropertyUtils.NESTED_DELIM, indexOfMAPPEDDELIM2);
209             }
210             else
211             {
212                 indexOfNESTEDDELIM = evalName.indexOf(PropertyUtils.NESTED_DELIM);
213             }
214             if (indexOfNESTEDDELIM < 0)
215             {
216                 break;
217             }
218             String   next = evalName.substring(0, indexOfNESTEDDELIM);
219             indexOfINDEXEDDELIM = next.indexOf(PropertyUtils.INDEXED_DELIM);
220             indexOfMAPPEDDELIM = next.indexOf(PropertyUtils.MAPPED_DELIM);
221             if (evalBean instanceof Map  )
222             {
223                 evalBean = ((Map  ) evalBean).get(next);
224             }
225             else if (indexOfMAPPEDDELIM >= 0)
226             {
227 
228                 evalBean = PropertyUtils.getMappedProperty(evalBean, next);
229 
230             }
231             else if (indexOfINDEXEDDELIM >= 0)
232             {
233                 evalBean = getIndexedProperty(evalBean, next);
234             }
235             else
236             {
237                 evalBean = PropertyUtils.getSimpleProperty(evalBean, next);
238             }
239 
240             if (evalBean == null)
241             {
242                 log.debug("Null property value for '" + evalName.substring(0, indexOfNESTEDDELIM) + "'");
243                 return null;
244             }
245             evalName = evalName.substring(indexOfNESTEDDELIM + 1);
246 
247         }
248 
249         indexOfINDEXEDDELIM = evalName.indexOf(PropertyUtils.INDEXED_DELIM);
250         indexOfMAPPEDDELIM = evalName.indexOf(PropertyUtils.MAPPED_DELIM);
251 
252         if (evalBean == null)
253         {
254             log.debug("Null property value for '" + evalName.substring(0, indexOfNESTEDDELIM) + "'");
255             return null;
256         }
257         else if (evalBean instanceof Map  )
258         {
259             evalBean = ((Map  ) evalBean).get(evalName);
260         }
261         else if (indexOfMAPPEDDELIM >= 0)
262         {
263             evalBean = PropertyUtils.getMappedProperty(evalBean, evalName);
264         }
265         else if (indexOfINDEXEDDELIM >= 0)
266         {
267             evalBean = getIndexedProperty(evalBean, evalName);
268         }
269         else
270         {
271             evalBean = PropertyUtils.getSimpleProperty(evalBean, evalName);
272         }
273 
274         return evalBean;
275 
276     }
277 
278     /**
279      * Return the value of the specified indexed property of the specified bean, with no type conversions. The
280      * zero-relative index of the required value must be included (in square brackets) as a suffix to the property name,
281      * or <code>IllegalArgumentException</code> will be thrown. In addition to supporting the JavaBeans specification,
282      * this method has been extended to support <code>List</code> objects as well.
283      * @param bean Bean whose property is to be extracted
284      * @param name <code>propertyname[index]</code> of the property value to be extracted
285      * @return Object
286      * @exception IllegalAccessException if the caller does not have access to the property accessor method
287      * @exception InvocationTargetException if the property accessor method throws an exception
288      * @exception NoSuchMethodException if an accessor method for this propety cannot be found
289      */
290     public static Object   getIndexedProperty(Object   bean, String   name) throws IllegalAccessException  ,
291         InvocationTargetException  , NoSuchMethodException  
292     {
293 
294         Validate.notNull(bean, "No bean specified");
295         Validate.notNull(name, "No name specified");
296 
297         String   evalName = name;
298 
299         // Identify the index of the requested individual property
300         int delim = evalName.indexOf(PropertyUtils.INDEXED_DELIM);
301         int delim2 = evalName.indexOf(PropertyUtils.INDEXED_DELIM2);
302         if ((delim < 0) || (delim2 <= delim))
303         {
304             throw new IllegalArgumentException  ("Invalid indexed property '" + evalName + "'");
305         }
306         int index = -1;
307         try
308         {
309             String   subscript = evalName.substring(delim + 1, delim2);
310             index = Integer.parseInt(subscript);
311         }
312         catch (NumberFormatException   e)
313         {
314             throw new IllegalArgumentException  ("Invalid indexed property '" + evalName + "'");
315         }
316         evalName = evalName.substring(0, delim);
317 
318         if (log.isDebugEnabled())
319         {
320             log.debug("getIndexedProperty property name={" + evalName + "} with index " + index);
321 
322         }
323 
324         // addd support for lists and arrays
325         if (StringUtils.isEmpty(evalName))
326         {
327             if (bean instanceof List  )
328             {
329                 return ((List  ) bean).get(index);
330             }
331             else if (bean.getClass().isArray())
332             {
333                 return ((Object  []) bean)[index];
334             }
335         }
336         // Request the specified indexed property value
337         return (PropertyUtils.getIndexedProperty(bean, evalName, index));
338 
339     }
340 
341 }
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