1、Object转Map

2、将 map 中的 value 为null的的元素转成空字符串""

3、map转Object

4、MAP 判空

5、Map 排序 按key值长度进行排序

6、两个MAP对比，在oldMap中移除remMap中所有的key值

备注：排序的话(TreeMap)是可以直接实现简单排序的，如果有复杂的业务场景可以重写Comparator

引入jar

<dependency><groupId>commons-beanutils</groupId><artifactId>commons-beanutils</artifactId><version>1.8.3</version></dependency>

import org.apache.commons.beanutils.BeanMap;
import org.apache.commons.beanutils.BeanUtils;import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.util.*;import static org.apache.commons.beanutils.BeanUtils.populate;/*** MAP工具类* TreeMap是有序的 默认正序排列*/
public class MapUtils {/*** Object转Map** @param obj* @return*/public static Map<?, ?> objectToMap(Object obj) {if (obj == null) {return null;}return new BeanMap(obj);}/*** Object转Map** @param obj* @return* @throws IllegalAccessException*/public static Map<?, ?> objectToMapA(Object obj) throws IllegalAccessException {if (obj == null) {return null;}Map<String, Object> map = new HashMap<>();Class<?> clazz = obj.getClass();for (Field field : clazz.getDeclaredFields()) {field.setAccessible(true);String fieldName = field.getName();Object value = field.get(obj);map.put(fieldName, value);}return map;}/*** Object 转MAP** @param obj* @return* @throws IllegalAccessException* @throws NoSuchMethodException* @throws InvocationTargetException*/public static Map<?, ?> objectToMapB(Object obj) throws IllegalAccessException, NoSuchMethodException, InvocationTargetException {if (obj == null) {return null;}//使用BeanUtils获取对象属性return BeanUtils.describe(obj);}/*** 将 map 中的 value 为null的的元素转成空字符串""** @param map* @return*/public static Map<Integer, String> valueConvertString(Map<Integer, String> map) {map.forEach((k, v) -> {if (null == v || "".equals(v)) {map.put(k, "\" \"");}});return map;}/*** map转Object** @param map* @param beanClass* @return* @throws Exception*/public static Object mapToObject(Map<String, Object> map, Class<?> beanClass) {if (map == null) {return null;}try {Object obj = beanClass.newInstance();populate(obj, map);return obj;} catch (Exception e) {e.printStackTrace();}return null;}/*** MAP 判空** @param map* @return*/public static boolean isEmpty(Map<?, ?> map) {return map == null || map.isEmpty();}/*** Map 排序   按key值长度进行排序** @param map* @return*/public static Map<String, String> sortMapByKey(Map<String, String> map) {if (CommonFunctions.isEmpty(map)) {return null;}Map<String, String> sortMap = new TreeMap<>(new MapKeyComparator());sortMap.putAll(map);return sortMap;}/*** 两个MAP对比，在oldMap中移除remMap中所有的key值** @param remMap 移除的key* @param oldMap 需要移除key值的MAP*/public static void removeKey(Map remMap, Map oldMap) {if (CommonFunctions.isEmpty(remMap) || CommonFunctions.isEmpty(remMap)) {return;}Iterator iterator = remMap.keySet().iterator();while (iterator.hasNext()) {String key = (String) iterator.next();oldMap.remove(key);}}public static void main(String[] args) {//只是简单的排序 这里足够用了Map<String, Object> map = new TreeMap<>();//正序map.put("A1", 3);map.put("D3", 1);map.put("B4", 2);map.put("C2", 4);map.forEach((k, v) -> System.out.println("正序====KEY==" + k + "====VALUE====" + v));Map<String, Object> mapDesc = new TreeMap<>(new MapKeyComparatorDesc());//倒序mapDesc.put("A1", 3);mapDesc.put("D3", 1);mapDesc.put("B4", 2);mapDesc.put("C2", 4);mapDesc.forEach((k, v) -> System.out.println("倒序====KEY==" + k + "====VALUE====" + v));Map<String, String> keyMap = new HashMap<>();keyMap.put("A", "Q");keyMap.put("AA", "Q");keyMap.put("AAAA", "Q");keyMap.put("AAA", "Q");keyMap.put("AAAAA", "Q");keyMap.forEach((k, v) -> System.out.println("排序前====KEY==" + k + "====VALUE====" + v));Map<String, String> map1 = sortMapByKey(keyMap);map1.forEach((k, v) -> System.out.println("排序后====KEY==" + k + "====VALUE====" + v));}}//比较1 (默认比较级倒转)
class MapKeyComparatorDesc implements Comparator {@Overridepublic int compare(Object o1, Object o2) {String i1 = (String) o1;String i2 = (String) o2;return -i1.compareTo(i2);}
}//比较2   （key值长度比较）
class MapKeyComparator implements Comparator<String> {@Overridepublic int compare(String o1, String o2) {if (o1.length() > o2.length()) {return -1;} else if (o1.length() < o2.length()) {return 1;} else {return o2.compareTo(o1);}}
}