beanUtils的使用

beanUtils的使用场景：

beanUtils对javaBean的属性或属性对象进行赋值
beanUtils获取javaBean属性
beanUtils克隆javaBean
beanUtils将javaBean转换为Map
beanUtils将Map转换为javaBean
beanUtils获取javaBean的数组集合字段值
beanUtils获取javaBean的Map字段值
beanUtils获取javaBean的嵌套字段值

1.beanUtils对javaBean的属性或属性对象进行赋值

从配置文件读取的都是String类型的数据或其他的类型，跟javaBean的属性类型不一致，beanUtils可以对其进行自动转换，有效的减少代码量：示例如下：

1 S1 s = new S1();  
2 BeanUtils.setProperty(s, "id", id);  的对象
3 BeanUtils.setProperty(s, "name", name);

若改变其转换的类型则可自定义实现类型转换器：

 1 @Override
 2  public Object convert(Class  type, Object value) { 
 3      if(type != Date.class)  return null;
 4          if (value == null ||"".equals(value.toString().trim())) {
 5             return null;
 6           }
 7        SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
 8        Date date = null;
 9        try {
10        date = dateFormat.parse((String)value);
11        } catch (ParseException e) {
12              throw new RuntimeException(e);
13             }
14          return date;
15        }
16 }, Date.class);

2.具体查看源码如：

  1 /*
  2  * Licensed to the Apache Software Foundation (ASF) under one or more
  3  * contributor license agreements.  See the NOTICE file distributed with
  4  * this work for additional information regarding copyright ownership.
  5  * The ASF licenses this file to You under the Apache License, Version 2.0
  6  * (the "License"); you may not use this file except in compliance with
  7  * the License.  You may obtain a copy of the License at
  8  *
  9  *      http://www.apache.org/licenses/LICENSE-2.0
 10  *
 11  * Unless required by applicable law or agreed to in writing, software
 12  * distributed under the License is distributed on an "AS IS" BASIS,
 13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 14  * See the License for the specific language governing permissions and
 15  * limitations under the License.
 16  */
 17 
 18 
 19 package org.apache.commons.beanutils;
 20 
 21 import java.lang.reflect.InvocationTargetException;
 22 import java.util.Map;
 23 
 24 
 25 
 26 /**
 27  * <p>Utility methods for populating JavaBeans properties via reflection.</p>
 28  *
 29  * <p>The implementations are provided by {@link BeanUtilsBean}.
 30  * These static utility methods use the default instance.
 31  * More sophisticated behaviour can be provided by using a <code>BeanUtilsBean</code> instance.</p>
 32  *
 33  * @author Craig R. McClanahan
 34  * @author Ralph Schaer
 35  * @author Chris Audley
 36  * @author Rey Francois
 37  * @author Gregor Rayman
 38  * @version $Revision: 690380 $ $Date: 2008-08-29 21:04:38 +0100 (Fri, 29 Aug 2008) $
 39  * @see BeanUtilsBean
 40  */
 41 
 42 public class BeanUtils {
 43 
 44 
 45     // ------------------------------------------------------ Private Variables
 46 
 47 
 48     /**
 49      * The debugging detail level for this component.
 50      * 
 51      * Note that this static variable will have unexpected side-effects if
 52      * this class is deployed in a shared classloader within a container.
 53      * However as it is actually completely ignored by this class due to its
 54      * deprecated status, it doesn't do any actual harm.
 55      * 
 56      * @deprecated BeanUtils now uses commons-logging for all log messages.
 57      *             Use your favorite logging tool to configure logging for
 58      *             this class.
 59      */
 60     private static int debug = 0;
 61 
 62     /**
 63      * The <code>debug</code> static property is no longer used
 64      * @return debug property
 65      * @deprecated BeanUtils now uses commons-logging for all log messages.
 66      *             Use your favorite logging tool to configure logging for
 67      *             this class.
 68      */
 69     public static int getDebug() {
 70         return (debug);
 71     }
 72 
 73     /**
 74      * The <code>debug</code> static property is no longer used
 75      * @param newDebug debug property
 76      * @deprecated BeanUtils now uses commons-logging for all log messages.
 77      *             Use your favorite logging tool to configure logging for
 78      *             this class.
 79      */
 80     public static void setDebug(int newDebug) {
 81         debug = newDebug;
 82     }
 83 
 84     // --------------------------------------------------------- Class Methods
 85 
 86 
 87     /**
 88      * <p>Clone a bean based on the available property getters and setters,
 89      * even if the bean class itself does not implement Cloneable.</p>
 90      *
 91      * <p>For more details see <code>BeanUtilsBean</code>.</p>
 92      *
 93      * @param bean Bean to be cloned
 94      * @return the cloned bean
 95      *
 96      * @exception IllegalAccessException if the caller does not have
 97      *  access to the property accessor method
 98      * @exception InstantiationException if a new instance of the bean's
 99      *  class cannot be instantiated
100      * @exception InvocationTargetException if the property accessor method
101      *  throws an exception
102      * @exception NoSuchMethodException if an accessor method for this
103      *  property cannot be found
104      * @see BeanUtilsBean#cloneBean
105      */
106     public static Object cloneBean(Object bean)
107             throws IllegalAccessException, InstantiationException,
108             InvocationTargetException, NoSuchMethodException {
109 
110         return BeanUtilsBean.getInstance().cloneBean(bean);
111 
112     }
113 
114 
115     /**
116      * <p>Copy property values from the origin bean to the destination bean
117      * for all cases where the property names are the same.</p>
118      *
119      * <p>For more details see <code>BeanUtilsBean</code>.</p>
120      *
121      * @param dest Destination bean whose properties are modified
122      * @param orig Origin bean whose properties are retrieved
123      *
124      * @exception IllegalAccessException if the caller does not have
125      *  access to the property accessor method
126      * @exception IllegalArgumentException if the <code>dest</code> or
127      *  <code>orig</code> argument is null or if the <code>dest</code> 
128      *  property type is different from the source type and the relevant
129      *  converter has not been registered.
130      * @exception InvocationTargetException if the property accessor method
131      *  throws an exception
132      * @see BeanUtilsBean#copyProperties
133      */
134     public static void copyProperties(Object dest, Object orig)
135         throws IllegalAccessException, InvocationTargetException {
136         
137         BeanUtilsBean.getInstance().copyProperties(dest, orig);
138     }
139 
140 
141     /**
142      * <p>Copy the specified property value to the specified destination bean,
143      * performing any type conversion that is required.</p>    
144      *
145      * <p>For more details see <code>BeanUtilsBean</code>.</p>
146      *
147      * @param bean Bean on which setting is to be performed
148      * @param name Property name (can be nested/indexed/mapped/combo)
149      * @param value Value to be set
150      *
151      * @exception IllegalAccessException if the caller does not have
152      *  access to the property accessor method
153      * @exception InvocationTargetException if the property accessor method
154      *  throws an exception
155      * @see BeanUtilsBean#copyProperty     
156      */
157     public static void copyProperty(Object bean, String name, Object value)
158         throws IllegalAccessException, InvocationTargetException {
159 
160         BeanUtilsBean.getInstance().copyProperty(bean, name, value);
161     }
162 
163 
164     /**
165      * <p>Return the entire set of properties for which the specified bean
166      * provides a read method.</p>
167      *
168      * <p>For more details see <code>BeanUtilsBean</code>.</p>
169      *
170      * @param bean Bean whose properties are to be extracted
171      * @return Map of property descriptors
172      *
173      * @exception IllegalAccessException if the caller does not have
174      *  access to the property accessor method
175      * @exception InvocationTargetException if the property accessor method
176      *  throws an exception
177      * @exception NoSuchMethodException if an accessor method for this
178      *  property cannot be found
179      * @see BeanUtilsBean#describe 
180      */
181     public static Map describe(Object bean)
182             throws IllegalAccessException, InvocationTargetException,
183             NoSuchMethodException {
184 
185         return BeanUtilsBean.getInstance().describe(bean);
186     }
187 
188 
189     /**
190      * <p>Return the value of the specified array property of the specified
191      * bean, as a String array.</p>
192      *
193      * <p>For more details see <code>BeanUtilsBean</code>.</p>
194      *
195      * @param bean Bean whose property is to be extracted
196      * @param name Name of the property to be extracted
197      * @return The array property value
198      *
199      * @exception IllegalAccessException if the caller does not have
200      *  access to the property accessor method
201      * @exception InvocationTargetException if the property accessor method
202      *  throws an exception
203      * @exception NoSuchMethodException if an accessor method for this
204      *  property cannot be found
205      * @see BeanUtilsBean#getArrayProperty 
206      */
207     public static String[] getArrayProperty(Object bean, String name)
208             throws IllegalAccessException, InvocationTargetException,
209             NoSuchMethodException {
210 
211         return BeanUtilsBean.getInstance().getArrayProperty(bean, name);
212     }
213 
214 
215     /**
216      * <p>Return the value of the specified indexed property of the specified
217      * bean, as a String.</p>
218      *
219      * <p>For more details see <code>BeanUtilsBean</code>.</p>
220      *
221      * @param bean Bean whose property is to be extracted
222      * @param name <code>propertyname[index]</code> of the property value
223      *  to be extracted
224      * @return The indexed property's value, converted to a String
225      *
226      * @exception IllegalAccessException if the caller does not have
227      *  access to the property accessor method
228      * @exception InvocationTargetException if the property accessor method
229      *  throws an exception
230      * @exception NoSuchMethodException if an accessor method for this
231      *  property cannot be found
232      * @see BeanUtilsBean#getIndexedProperty(Object, String)
233      */
234     public static String getIndexedProperty(Object bean, String name)
235             throws IllegalAccessException, InvocationTargetException,
236             NoSuchMethodException {
237         
238         return BeanUtilsBean.getInstance().getIndexedProperty(bean, name);
239 
240     }
241 
242 
243     /**
244      * Return the value of the specified indexed property of the specified
245      * bean, as a String.  The index is specified as a method parameter and
246      * must *not* be included in the property name expression
247      *
248      * <p>For more details see <code>BeanUtilsBean</code>.</p>
249      *
250      * @param bean Bean whose property is to be extracted
251      * @param name Simple property name of the property value to be extracted
252      * @param index Index of the property value to be extracted
253      * @return The indexed property's value, converted to a String
254      *
255      * @exception IllegalAccessException if the caller does not have
256      *  access to the property accessor method
257      * @exception InvocationTargetException if the property accessor method
258      *  throws an exception
259      * @exception NoSuchMethodException if an accessor method for this
260      *  property cannot be found
261      * @see BeanUtilsBean#getIndexedProperty(Object, String, int)
262      */
263     public static String getIndexedProperty(Object bean,
264                                             String name, int index)
265             throws IllegalAccessException, InvocationTargetException,
266             NoSuchMethodException {
267 
268         return BeanUtilsBean.getInstance().getIndexedProperty(bean, name, index);
269 
270     }
271 
272 
273     /**
274      * </p>Return the value of the specified indexed property of the specified
275      * bean, as a String.</p>
276      *
277      * <p>For more details see <code>BeanUtilsBean</code>.</p>
278      *
279      * @param bean Bean whose property is to be extracted
280      * @param name <code>propertyname(index)</code> of the property value
281      *  to be extracted
282      * @return The mapped property's value, converted to a String
283      *
284      * @exception IllegalAccessException if the caller does not have
285      *  access to the property accessor method
286      * @exception InvocationTargetException if the property accessor method
287      *  throws an exception
288      * @exception NoSuchMethodException if an accessor method for this
289      *  property cannot be found
290      * @see BeanUtilsBean#getMappedProperty(Object, String)
291      */
292     public static String getMappedProperty(Object bean, String name)
293             throws IllegalAccessException, InvocationTargetException,
294             NoSuchMethodException {
295 
296         return BeanUtilsBean.getInstance().getMappedProperty(bean, name);
297 
298     }
299 
300 
301     /**
302      * </p>Return the value of the specified mapped property of the specified
303      * bean, as a String.</p>
304      *
305      * <p>For more details see <code>BeanUtilsBean</code>.</p>
306      *
307      * @param bean Bean whose property is to be extracted
308      * @param name Simple property name of the property value to be extracted
309      * @param key Lookup key of the property value to be extracted
310      * @return The mapped property's value, converted to a String
311      *
312      * @exception IllegalAccessException if the caller does not have
313      *  access to the property accessor method
314      * @exception InvocationTargetException if the property accessor method
315      *  throws an exception
316      * @exception NoSuchMethodException if an accessor method for this
317      *  property cannot be found
318      * @see BeanUtilsBean#getMappedProperty(Object, String, String)
319      */
320     public static String getMappedProperty(Object bean,
321                                            String name, String key)
322             throws IllegalAccessException, InvocationTargetException,
323             NoSuchMethodException {
324 
325         return BeanUtilsBean.getInstance().getMappedProperty(bean, name, key);
326 
327     }
328 
329 
330     /**
331      * <p>Return the value of the (possibly nested) property of the specified
332      * name, for the specified bean, as a String.</p>
333      *
334      * <p>For more details see <code>BeanUtilsBean</code>.</p>
335      *
336      * @param bean Bean whose property is to be extracted
337      * @param name Possibly nested name of the property to be extracted
338      * @return The nested property's value, converted to a String
339      *
340      * @exception IllegalAccessException if the caller does not have
341      *  access to the property accessor method
342      * @exception IllegalArgumentException if a nested reference to a
343      *  property returns null
344      * @exception InvocationTargetException if the property accessor method
345      *  throws an exception
346      * @exception NoSuchMethodException if an accessor method for this
347      *  property cannot be found
348      * @see BeanUtilsBean#getNestedProperty
349      */
350     public static String getNestedProperty(Object bean, String name)
351             throws IllegalAccessException, InvocationTargetException,
352             NoSuchMethodException {
353 
354         return BeanUtilsBean.getInstance().getNestedProperty(bean, name);
355 
356     }
357 
358 
359     /**
360      * <p>Return the value of the specified property of the specified bean,
361      * no matter which property reference format is used, as a String.</p>
362      *
363      * <p>For more details see <code>BeanUtilsBean</code>.</p>
364      *
365      * @param bean Bean whose property is to be extracted
366      * @param name Possibly indexed and/or nested name of the property
367      *  to be extracted
368      * @return The property's value, converted to a String
369      *
370      * @exception IllegalAccessException if the caller does not have
371      *  access to the property accessor method
372      * @exception InvocationTargetException if the property accessor method
373      *  throws an exception
374      * @exception NoSuchMethodException if an accessor method for this
375      *  property cannot be found
376      * @see BeanUtilsBean#getProperty
377      */
378     public static String getProperty(Object bean, String name)
379             throws IllegalAccessException, InvocationTargetException,
380             NoSuchMethodException {
381 
382         return BeanUtilsBean.getInstance().getProperty(bean, name);
383 
384     }
385 
386 
387     /**
388      * <p>Return the value of the specified simple property of the specified
389      * bean, converted to a String.</p>
390      *
391      * <p>For more details see <code>BeanUtilsBean</code>.</p>
392      *
393      * @param bean Bean whose property is to be extracted
394      * @param name Name of the property to be extracted
395      * @return The property's value, converted to a String
396      *
397      * @exception IllegalAccessException if the caller does not have
398      *  access to the property accessor method
399      * @exception InvocationTargetException if the property accessor method
400      *  throws an exception
401      * @exception NoSuchMethodException if an accessor method for this
402      *  property cannot be found
403      * @see BeanUtilsBean#getSimpleProperty
404      */
405     public static String getSimpleProperty(Object bean, String name)
406             throws IllegalAccessException, InvocationTargetException,
407             NoSuchMethodException {
408 
409         return BeanUtilsBean.getInstance().getSimpleProperty(bean, name);
410 
411     }
412 
413 
414     /**
415      * <p>Populate the JavaBeans properties of the specified bean, based on
416      * the specified name/value pairs.</p>
417      *
418      * <p>For more details see <code>BeanUtilsBean</code>.</p>
419      *
420      * @param bean JavaBean whose properties are being populated
421      * @param properties Map keyed by property name, with the
422      *  corresponding (String or String[]) value(s) to be set
423      *
424      * @exception IllegalAccessException if the caller does not have
425      *  access to the property accessor method
426      * @exception InvocationTargetException if the property accessor method
427      *  throws an exception
428      * @see BeanUtilsBean#populate
429      */
430     public static void populate(Object bean, Map properties)
431         throws IllegalAccessException, InvocationTargetException {
432         
433         BeanUtilsBean.getInstance().populate(bean, properties);
434     }
435 
436 
437     /**
438      * <p>Set the specified property value, performing type conversions as
439      * required to conform to the type of the destination property.</p>
440      *
441      * <p>For more details see <code>BeanUtilsBean</code>.</p>
442      *
443      * @param bean Bean on which setting is to be performed
444      * @param name Property name (can be nested/indexed/mapped/combo)
445      * @param value Value to be set
446      *
447      * @exception IllegalAccessException if the caller does not have
448      *  access to the property accessor method
449      * @exception InvocationTargetException if the property accessor method
450      *  throws an exception
451      * @see BeanUtilsBean#setProperty
452      */
453     public static void setProperty(Object bean, String name, Object value)
454         throws IllegalAccessException, InvocationTargetException {
455 
456         BeanUtilsBean.getInstance().setProperty(bean, name, value);
457     }
458 
459     /** 
460      * If we're running on JDK 1.4 or later, initialize the cause for the given throwable.
461      * 
462      * @param  throwable The throwable.
463      * @param  cause     The cause of the throwable.
464      * @return  true if the cause was initialized, otherwise false.
465      * @since 1.8.0
466      */
467     public static boolean initCause(Throwable throwable, Throwable cause) {
468         return BeanUtilsBean.getInstance().initCause(throwable, cause);
469     }
470 
471     /**
472      * Create a cache.
473      * @return a new cache
474      * @since 1.8.0
475      */
476     public static Map createCache() {
477         return new WeakFastHashMap();
478     }
479 
480     /**
481      * Return whether a Map is fast
482      * @param map The map
483      * @return Whether it is fast or not.
484      * @since 1.8.0
485      */
486     public static boolean getCacheFast(Map map) {
487         if (map instanceof WeakFastHashMap) {
488             return ((WeakFastHashMap)map).getFast();
489         } else {
490             return false;
491         }
492     }
493 
494     /**
495      * Set whether fast on a Map
496      * @param map The map
497      * @param fast Whether it should be fast or not.
498      * @since 1.8.0
499      */
500     public static void setCacheFast(Map map, boolean fast) {
501         if (map instanceof WeakFastHashMap) {
502             ((WeakFastHashMap)map).setFast(fast);
503         }
504     }
505 }

View Code