專案環境：

jdk1.8+spring4.3.12

一、問題描述及試用場景：
在專案規範中，要求類名以DO為尾的類作為資料庫層實體bean，類名以MO為尾的類作為系統傳輸層實體bean，類名以VO為尾的類作為服務端與前端互動的實體bean。由於以上要求，需要在各個bean直接進行copy資料，除了傻瓜式的set/get or constructor來copy資料外，spring提供了直接copybean的工具類，原理其實就是通過java反射來根據目標bean的欄位名呼叫其set方法來設值注入。除此之外，專案中還常見map與bean之間的轉換。特封裝此類，以供大家使用。

二、樣例程式碼：

package
 
 org.egg.utils;

import org.egg.enums.CommonErrorEnum;
import org.egg.exception.CommonException;
import org.springframework.beans.BeanUtils;
import org.springframework.util.CollectionUtils;

import java.beans.BeanInfo;
import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import
 
 java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * @author dataochen
 * @Description bean工具類
 * @date: 2017/11/7 17:30
 */
public class BeanUtil {

    /**
     * 拷貝實體，source,target不允許為空
     *
     * @param
 
 source
     * @param target
     */
    public static void copyProperties(Object source, Object target) {
        BeanUtils.copyProperties(source, target);
    }

    /**
     * 拷貝實體集合，sourceList
     *只支援自定義實體集合拷貝 
     *應用場景：DTO <=> DO 等
     */

public static void copyPropertiesList(List sourceList, List targetList,Class clazz) throws InstantiationException,IllegalAccessException {
    if (CollectionUtils.isEmpty(sourceList)) {
        throw new CommonException(CommonErrorEnum.PARAM_ERROR);
    }
    for (Object items : sourceList) {
        Object target = clazz.newInstance();
        BeanUtils.copyProperties(items, target);
        targetList.add(target);
    }

}

/**
 * Map --> Bean 2: 利用org.apache.commons.beanutils 工具類實現 Map --> Bean
 *
 * @param map
 * @param obj
 */
public static void transMap2Bean2(Map<String, Object> map, Object obj) throws InvocationTargetException, IllegalAccessException {
    if (map == null || obj == null) {
        return;
    }
    org.apache.commons.beanutils.BeanUtils.populate(obj, map);
}

/**
 * Map --> Bean 1: 利用Introspector,PropertyDescriptor實現 Map --> Bean
 *
 * @param map
 * @param obj
 */
public static void transMap2Bean(Map<String, Object> map, Object obj) throws IntrospectionException, InvocationTargetException, IllegalAccessException {
    BeanInfo beanInfo = Introspector.getBeanInfo(obj.getClass());
    PropertyDescriptor[] propertyDescriptors = beanInfo.getPropertyDescriptors();

    for (PropertyDescriptor property : propertyDescriptors) {
        String key = property.getName();
        if (map.containsKey(key)) {
            Object value = map.get(key);
            // 得到property對應的setter方法
            Method setter = property.getWriteMethod();
            setter.invoke(obj, value);
        }
    }
}

/**
 * Bean --> Map 1: 利用Introspector和PropertyDescriptor 將Bean --> Map
 *
 * @param obj
 */
public static Map<String, Object> transBean2Map(Object obj) throws IntrospectionException, InvocationTargetException, IllegalAccessException {

    if (obj == null) {
        return null;
    }
    Map<String, Object> map = new HashMap<String, Object>();
    BeanInfo beanInfo = Introspector.getBeanInfo(obj.getClass());
    PropertyDescriptor[] propertyDescriptors = beanInfo.getPropertyDescriptors();
    for (PropertyDescriptor property : propertyDescriptors) {
        String key = property.getName();

        // 過濾class屬性
        if (!key.equals("class")) {
            // 得到property對應的getter方法
            Method getter = property.getReadMethod();
            Object value = getter.invoke(obj);

            map.put(key, value);
        }

    }
    return map;
}

程式碼所用jar包maven座標：

<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-core</artifactId>
    <version>4.3.12.RELEASE</version>
</dependency>

<!-- https://mvnrepository.com/artifact/org.springframework/spring-beans -->
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-beans</artifactId>
    <version>4.3.12.RELEASE</version>
</dependency>