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：

S1 s = new S1();  
BeanUtils.setProperty(s, "id", id);  的对象
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：

@Override
 public Object convert(Class  type, Object value) { 
     if(type != Date.class)  return null;
         if (value == null ||"".equals(value.toString().trim())) {
            return null;
          }
       SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
       Date date = null;
       try {
       date = dateFormat.parse((String)value);
       } catch (ParseException e) {
             throw new RuntimeException(e);
            }
         return date;
       }
}, Date.class);  

 2.具体查看源码如：

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.commons.beanutils;

import java.lang.reflect.InvocationTargetException;
import java.util.Map;



/**
 * <p>Utility methods for populating JavaBeans properties via reflection.</p>
 *
 * <p>The implementations are provided by {@link BeanUtilsBean}.
 * These static utility methods use the default instance.
 * More sophisticated behaviour can be provided by using a <code>BeanUtilsBean</code> instance.</p>
 *
 * @author Craig R. McClanahan
 * @author Ralph Schaer
 * @author Chris Audley
 * @author Rey Francois
 * @author Gregor Rayman
 * @version $Revision: 690380 $ $Date: 2008-08-29 21:04:38 +0100 (Fri, 29 Aug 2008) $
 * @see BeanUtilsBean
 */

public class BeanUtils {


    // ------------------------------------------------------ Private Variables


    /**
     * The debugging detail level for this component.
     * 
     * Note that this static variable will have unexpected side-effects if
     * this class is deployed in a shared classloader within a container.
     * However as it is actually completely ignored by this class due to its
     * deprecated status, it doesn't do any actual harm.
     * 
     * @deprecated BeanUtils now uses commons-logging for all log messages.
     *             Use your favorite logging tool to configure logging for
     *             this class.
     */
    private static int debug = 0;

    /**
     * The <code>debug</code> static property is no longer used
     * @return debug property
     * @deprecated BeanUtils now uses commons-logging for all log messages.
     *             Use your favorite logging tool to configure logging for
     *             this class.
     */
    public static int getDebug() {
        return (debug);
    }

    /**
     * The <code>debug</code> static property is no longer used
     * @param newDebug debug property
     * @deprecated BeanUtils now uses commons-logging for all log messages.
     *             Use your favorite logging tool to configure logging for
     *             this class.
     */
    public static void setDebug(int newDebug) {
        debug = newDebug;
    }

    // --------------------------------------------------------- Class Methods


    /**
     * <p>Clone a bean based on the available property getters and setters,
     * even if the bean class itself does not implement Cloneable.</p>
     *
     * <p>For more details see <code>BeanUtilsBean</code>.</p>
     *
     * @param bean Bean to be cloned
     * @return the cloned bean
     *
     * @exception IllegalAccessException if the caller does not have
     *  access to the property accessor method
     * @exception InstantiationException if a new instance of the bean's
     *  class cannot be instantiated
     * @exception InvocationTargetException if the property accessor method
     *  throws an exception
     * @exception NoSuchMethodException if an accessor method for this
     *  property cannot be found
     * @see BeanUtilsBean#cloneBean
     */
    public static Object cloneBean(Object bean)
            throws IllegalAccessException, InstantiationException,
            InvocationTargetException, NoSuchMethodException {

        return BeanUtilsBean.getInstance().cloneBean(bean);

    }


    /**
     * <p>Copy property values from the origin bean to the destination bean
     * for all cases where the property names are the same.</p>
     *
     * <p>For more details see <code>BeanUtilsBean</code>.</p>
     *
     * @param dest Destination bean whose properties are modified
     * @param orig Origin bean whose properties are retrieved
     *
     * @exception IllegalAccessException if the caller does not have
     *  access to the property accessor method
     * @exception IllegalArgumentException if the <code>dest</code> or
     *  <code>orig</code> argument is null or if the <code>dest</code> 
     *  property type is different from the source type and the relevant
     *  converter has not been registered.
     * @exception InvocationTargetException if the property accessor method
     *  throws an exception
     * @see BeanUtilsBean#copyProperties
     */
    public static void copyProperties(Object dest, Object orig)
        throws IllegalAccessException, InvocationTargetException {
        
        BeanUtilsBean.getInstance().copyProperties(dest, orig);
    }


    /**
     * <p>Copy the specified property value to the specified destination bean,
     * performing any type conversion that is required.</p>    
     *
     * <p>For more details see <code>BeanUtilsBean</code>.</p>
     *
     * @param bean Bean on which setting is to be performed
     * @param name Property name (can be nested/indexed/mapped/combo)
     * @param value Value to be set
     *
     * @exception IllegalAccessException if the caller does not have
     *  access to the property accessor method
     * @exception InvocationTargetException if the property accessor method
     *  throws an exception
     * @see BeanUtilsBean#copyProperty     
     */
    public static void copyProperty(Object bean, String name, Object value)
        throws IllegalAccessException, InvocationTargetException {

        BeanUtilsBean.getInstance().copyProperty(bean, name, value);
    }


    /**
     * <p>Return the entire set of properties for which the specified bean
     * provides a read method.</p>
     *
     * <p>For more details see <code>BeanUtilsBean</code>.</p>
     *
     * @param bean Bean whose properties are to be extracted
     * @return Map of property descriptors
     *
     * @exception IllegalAccessException if the caller does not have
     *  access to the property accessor method
     * @exception InvocationTargetException if the property accessor method
     *  throws an exception
     * @exception NoSuchMethodException if an accessor method for this
     *  property cannot be found
     * @see BeanUtilsBean#describe 
     */
    public static Map describe(Object bean)
            throws IllegalAccessException, InvocationTargetException,
            NoSuchMethodException {

        return BeanUtilsBean.getInstance().describe(bean);
    }


    /**
     * <p>Return the value of the specified array property of the specified
     * bean, as a String array.</p>
     *
     * <p>For more details see <code>BeanUtilsBean</code>.</p>
     *
     * @param bean Bean whose property is to be extracted
     * @param name Name of the property to be extracted
     * @return The array property value
     *
     * @exception IllegalAccessException if the caller does not have
     *  access to the property accessor method
     * @exception InvocationTargetException if the property accessor method
     *  throws an exception
     * @exception NoSuchMethodException if an accessor method for this
     *  property cannot be found
     * @see BeanUtilsBean#getArrayProperty 
     */
    public static String[] getArrayProperty(Object bean, String name)
            throws IllegalAccessException, InvocationTargetException,
            NoSuchMethodException {

        return BeanUtilsBean.getInstance().getArrayProperty(bean, name);
    }


    /**
     * <p>Return the value of the specified indexed property of the specified
     * bean, as a String.</p>
     *
     * <p>For more details see <code>BeanUtilsBean</code>.</p>
     *
     * @param bean Bean whose property is to be extracted
     * @param name <code>propertyname[index]</code> of the property value
     *  to be extracted
     * @return The indexed property's value, converted to a String
     *
     * @exception IllegalAccessException if the caller does not have
     *  access to the property accessor method
     * @exception InvocationTargetException if the property accessor method
     *  throws an exception
     * @exception NoSuchMethodException if an accessor method for this
     *  property cannot be found
     * @see BeanUtilsBean#getIndexedProperty(Object, String)
     */
    public static String getIndexedProperty(Object bean, String name)
            throws IllegalAccessException, InvocationTargetException,
            NoSuchMethodException {
        
        return BeanUtilsBean.getInstance().getIndexedProperty(bean, name);

    }


    /**
     * Return the value of the specified indexed property of the specified
     * bean, as a String.  The index is specified as a method parameter and
     * must *not* be included in the property name expression
     *
     * <p>For more details see <code>BeanUtilsBean</code>.</p>
     *
     * @param bean Bean whose property is to be extracted
     * @param name Simple property name of the property value to be extracted
     * @param index Index of the property value to be extracted
     * @return The indexed property's value, converted to a String
     *
     * @exception IllegalAccessException if the caller does not have
     *  access to the property accessor method
     * @exception InvocationTargetException if the property accessor method
     *  throws an exception
     * @exception NoSuchMethodException if an accessor method for this
     *  property cannot be found
     * @see BeanUtilsBean#getIndexedProperty(Object, String, int)
     */
    public static String getIndexedProperty(Object bean,
                                            String name, int index)
            throws IllegalAccessException, InvocationTargetException,
            NoSuchMethodException {

        return BeanUtilsBean.getInstance().getIndexedProperty(bean, name, index);

    }


    /**
     * </p>Return the value of the specified indexed property of the specified
     * bean, as a String.</p>
     *
     * <p>For more details see <code>BeanUtilsBean</code>.</p>
     *
     * @param bean Bean whose property is to be extracted
     * @param name <code>propertyname(index)</code> of the property value
     *  to be extracted
     * @return The mapped property's value, converted to a String
     *
     * @exception IllegalAccessException if the caller does not have
     *  access to the property accessor method
     * @exception InvocationTargetException if the property accessor method
     *  throws an exception
     * @exception NoSuchMethodException if an accessor method for this
     *  property cannot be found
     * @see BeanUtilsBean#getMappedProperty(Object, String)
     */
    public static String getMappedProperty(Object bean, String name)
            throws IllegalAccessException, InvocationTargetException,
            NoSuchMethodException {

        return BeanUtilsBean.getInstance().getMappedProperty(bean, name);

    }


    /**
     * </p>Return the value of the specified mapped property of the specified
     * bean, as a String.</p>
     *
     * <p>For more details see <code>BeanUtilsBean</code>.</p>
     *
     * @param bean Bean whose property is to be extracted
     * @param name Simple property name of the property value to be extracted
     * @param key Lookup key of the property value to be extracted
     * @return The mapped property's value, converted to a String
     *
     * @exception IllegalAccessException if the caller does not have
     *  access to the property accessor method
     * @exception InvocationTargetException if the property accessor method
     *  throws an exception
     * @exception NoSuchMethodException if an accessor method for this
     *  property cannot be found
     * @see BeanUtilsBean#getMappedProperty(Object, String, String)
     */
    public static String getMappedProperty(Object bean,
                                           String name, String key)
            throws IllegalAccessException, InvocationTargetException,
            NoSuchMethodException {

        return BeanUtilsBean.getInstance().getMappedProperty(bean, name, key);

    }


    /**
     * <p>Return the value of the (possibly nested) property of the specified
     * name, for the specified bean, as a String.</p>
     *
     * <p>For more details see <code>BeanUtilsBean</code>.</p>
     *
     * @param bean Bean whose property is to be extracted
     * @param name Possibly nested name of the property to be extracted
     * @return The nested property's value, converted to a String
     *
     * @exception IllegalAccessException if the caller does not have
     *  access to the property accessor method
     * @exception IllegalArgumentException if a nested reference to a
     *  property returns null
     * @exception InvocationTargetException if the property accessor method
     *  throws an exception
     * @exception NoSuchMethodException if an accessor method for this
     *  property cannot be found
     * @see BeanUtilsBean#getNestedProperty
     */
    public static String getNestedProperty(Object bean, String name)
            throws IllegalAccessException, InvocationTargetException,
            NoSuchMethodException {

        return BeanUtilsBean.getInstance().getNestedProperty(bean, name);

    }


    /**
     * <p>Return the value of the specified property of the specified bean,
     * no matter which property reference format is used, as a String.</p>
     *
     * <p>For more details see <code>BeanUtilsBean</code>.</p>
     *
     * @param bean Bean whose property is to be extracted
     * @param name Possibly indexed and/or nested name of the property
     *  to be extracted
     * @return The property's value, converted to a String
     *
     * @exception IllegalAccessException if the caller does not have
     *  access to the property accessor method
     * @exception InvocationTargetException if the property accessor method
     *  throws an exception
     * @exception NoSuchMethodException if an accessor method for this
     *  property cannot be found
     * @see BeanUtilsBean#getProperty
     */
    public static String getProperty(Object bean, String name)
            throws IllegalAccessException, InvocationTargetException,
            NoSuchMethodException {

        return BeanUtilsBean.getInstance().getProperty(bean, name);

    }


    /**
     * <p>Return the value of the specified simple property of the specified
     * bean, converted to a String.</p>
     *
     * <p>For more details see <code>BeanUtilsBean</code>.</p>
     *
     * @param bean Bean whose property is to be extracted
     * @param name Name of the property to be extracted
     * @return The property's value, converted to a String
     *
     * @exception IllegalAccessException if the caller does not have
     *  access to the property accessor method
     * @exception InvocationTargetException if the property accessor method
     *  throws an exception
     * @exception NoSuchMethodException if an accessor method for this
     *  property cannot be found
     * @see BeanUtilsBean#getSimpleProperty
     */
    public static String getSimpleProperty(Object bean, String name)
            throws IllegalAccessException, InvocationTargetException,
            NoSuchMethodException {

        return BeanUtilsBean.getInstance().getSimpleProperty(bean, name);

    }


    /**
     * <p>Populate the JavaBeans properties of the specified bean, based on
     * the specified name/value pairs.</p>
     *
     * <p>For more details see <code>BeanUtilsBean</code>.</p>
     *
     * @param bean JavaBean whose properties are being populated
     * @param properties Map keyed by property name, with the
     *  corresponding (String or String[]) value(s) to be set
     *
     * @exception IllegalAccessException if the caller does not have
     *  access to the property accessor method
     * @exception InvocationTargetException if the property accessor method
     *  throws an exception
     * @see BeanUtilsBean#populate
     */
    public static void populate(Object bean, Map properties)
        throws IllegalAccessException, InvocationTargetException {
        
        BeanUtilsBean.getInstance().populate(bean, properties);
    }


    /**
     * <p>Set the specified property value, performing type conversions as
     * required to conform to the type of the destination property.</p>
     *
     * <p>For more details see <code>BeanUtilsBean</code>.</p>
     *
     * @param bean Bean on which setting is to be performed
     * @param name Property name (can be nested/indexed/mapped/combo)
     * @param value Value to be set
     *
     * @exception IllegalAccessException if the caller does not have
     *  access to the property accessor method
     * @exception InvocationTargetException if the property accessor method
     *  throws an exception
     * @see BeanUtilsBean#setProperty
     */
    public static void setProperty(Object bean, String name, Object value)
        throws IllegalAccessException, InvocationTargetException {

        BeanUtilsBean.getInstance().setProperty(bean, name, value);
    }

    /** 
     * If we're running on JDK 1.4 or later, initialize the cause for the given throwable.
     * 
     * @param  throwable The throwable.
     * @param  cause     The cause of the throwable.
     * @return  true if the cause was initialized, otherwise false.
     * @since 1.8.0
     */
    public static boolean initCause(Throwable throwable, Throwable cause) {
        return BeanUtilsBean.getInstance().initCause(throwable, cause);
    }

    /**
     * Create a cache.
     * @return a new cache
     * @since 1.8.0
     */
    public static Map createCache() {
        return new WeakFastHashMap();
    }

    /**
     * Return whether a Map is fast
     * @param map The map
     * @return Whether it is fast or not.
     * @since 1.8.0
     */
    public static boolean getCacheFast(Map map) {
        if (map instanceof WeakFastHashMap) {
            return ((WeakFastHashMap)map).getFast();
        } else {
            return false;
        }
    }

    /**
     * Set whether fast on a Map
     * @param map The map
     * @param fast Whether it should be fast or not.
     * @since 1.8.0
     */
    public static void setCacheFast(Map map, boolean fast) {
        if (map instanceof WeakFastHashMap) {
            ((WeakFastHashMap)map).setFast(fast);
        }
    }
}