java List 속성 별로 도구 클래스 나 누 기

package com.iflytek.bim.dms.common.core.util;

import org.apache.commons.lang.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

/**
 * @author xghuang
 * @date 2018/6/22
 * @time 13:23
 * @desc:
 */
public class GroupUtil {

    private static final Logger LOGGER = LoggerFactory.getLogger(GroupUtil.class);

    /**
     *  List  V methodName     （      K  ）  ，   Map> 

     *       method   V           ，         K  
     *
     * @param list       
     * @param map       map
     * @param clazz   V   
     * @param methodName    
     */
    public static  void listGroup2Map(List list, Map> map, Class clazz, String methodName) {
        //        
        if (null == list || null == map || null == clazz || StringUtils.isBlank(methodName)) {
            LOGGER.error("CommonUtils.listGroup2Map     ，list：" + list + " ；map：" + map
                    + " ；clazz：" + clazz + " ；methodName：" + methodName);
            return;
        }

        //     
        Method method = getMethodByName(clazz, methodName);
        //     
        if (null == method) {
            return;
        }

        //     
        listGroup2Map(list, map, method);
    }

    /**
     *  List  V        （      K  ）  ，   Map> 

     *       method   V           ，         K  
     *
     * @param list       
     * @param map       map
     * @param method   
     */
    @SuppressWarnings("unchecked")
    private static  void listGroup2Map(List list, Map> map, Method method) {
        //        
        if (null == list || null == map || null == method) {
            LOGGER.error("CommonUtils.listGroup2Map     ，list：" + list + " ；map：" + map
                    + " ；method：" + method);
            return;
        }

        try {
            //     
            Object key;
            List listTmp;
            for (V val : list) {
                key = method.invoke(val);
                listTmp = map.get(key);
                if (null == listTmp) {
                    listTmp = new ArrayList();
                    map.put((K) key, listTmp);
                }
                listTmp.add(val);
            }
        } catch (Exception e) {
            LOGGER.error("    ！", e);
        }
    }

    /**
     *        ，      
     *
     * @param clazz
     * @param methodName
     * @return
     */
    private static Method getMethodByName(Class> clazz, String methodName) {
        Method method = null;
        //       
        if (null == clazz || StringUtils.isBlank(methodName)) {
            LOGGER.error("CommonUtils.getMethodByName     ，clazz：" + clazz + " ；methodName："
                    + methodName);
            return method;
        }

        try {
            method = clazz.getDeclaredMethod(methodName);
        } catch (Exception e) {
            LOGGER.error("       ！", e);
        }

        return method;
    }
}