diff --git a/hutool-core/src/main/java/cn/hutool/core/map/MapUtil.java b/hutool-core/src/main/java/cn/hutool/core/map/MapUtil.java
index 63b8c02b7..9cfee1744 100644
--- a/hutool-core/src/main/java/cn/hutool/core/map/MapUtil.java
+++ b/hutool-core/src/main/java/cn/hutool/core/map/MapUtil.java
@@ -27,6 +27,8 @@ import java.util.Set;
import java.util.SortedMap;
import java.util.TreeMap;
import java.util.concurrent.ConcurrentHashMap;
+import java.util.stream.Collectors;
+import java.util.function.BiFunction;
/**
* Map相关工具类
@@ -548,7 +550,7 @@ public class MapUtil {
* @since 5.0.4
*/
public static String sortJoin(Map, ?> params, String separator, String keyValueSeparator, boolean isIgnoreNull,
- String... otherParams) {
+ String... otherParams) {
return join(sort(params), separator, keyValueSeparator, isIgnoreNull, otherParams);
}
@@ -668,6 +670,25 @@ public class MapUtil {
return edit(map, t -> filter.accept(t) ? t : null);
}
+
+ /**
+ * 变更
+ * 变更过程通过传入的 {@link BiFunction} 实现来返回一个值可以为不同类型的 {@link Map}
+ *
+ * @param map 原有的map
+ * @param biFunction {@code lambda},参数包含{@code key},{@code value},返回值会作为新的{@code value}
+ * @param {@code key}的类型
+ * @param {@code value}的类型
+ * @param 新的,修改后的{@code value}的类型
+ * @return 值可以为不同类型的 {@link Map}
+ */
+ public static Map change(Map map, BiFunction biFunction) {
+ if (null == map || null == biFunction) {
+ return MapUtil.newHashMap();
+ }
+ return map.entrySet().stream().collect(Collectors.toMap(Map.Entry::getKey, m -> biFunction.apply(m.getKey(), m.getValue())));
+ }
+
/**
* 过滤Map保留指定键值对,如果键不存在跳过
*
diff --git a/hutool-core/src/test/java/cn/hutool/core/map/MapUtilTest.java b/hutool-core/src/test/java/cn/hutool/core/map/MapUtilTest.java
index ed47980fe..58ce564a1 100644
--- a/hutool-core/src/test/java/cn/hutool/core/map/MapUtilTest.java
+++ b/hutool-core/src/test/java/cn/hutool/core/map/MapUtilTest.java
@@ -1,15 +1,44 @@
package cn.hutool.core.map;
import cn.hutool.core.convert.Convert;
+import cn.hutool.core.lang.Opt;
import cn.hutool.core.util.StrUtil;
+import lombok.Builder;
+import lombok.Data;
import org.junit.Assert;
import org.junit.Test;
-import java.util.HashMap;
-import java.util.Map;
+import java.util.*;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
public class MapUtilTest {
+ enum PeopleEnum {GIRL, BOY, CHILD}
+
+ @Data
+ @Builder
+ public static class User {
+ private Long id;
+ private String name;
+ }
+
+ @Data
+ @Builder
+ public static class Group {
+ private Long id;
+ private List users;
+ }
+
+ @Data
+ @Builder
+ public static class UserGroup {
+ private Long userId;
+ private Long groupId;
+ }
+
+
@Test
public void filterTest() {
Map map = MapUtil.newHashMap();
@@ -26,6 +55,47 @@ public class MapUtilTest {
Assert.assertEquals("4", map2.get("d"));
}
+ @Test
+ public void changeTest() {
+ // Add test like a foreigner
+ Map adjectivesMap = MapUtil.builder()
+ .put(0, "lovely")
+ .put(1, "friendly")
+ .put(2, "happily")
+ .build();
+
+ Map resultMap = MapUtil.change(adjectivesMap, (k, v) -> v + " " + PeopleEnum.values()[k].name().toLowerCase());
+
+ Assert.assertEquals("lovely girl", resultMap.get(0));
+ Assert.assertEquals("friendly boy", resultMap.get(1));
+ Assert.assertEquals("happily child", resultMap.get(2));
+
+ // 下单用户,Queue表示正在 .排队. 抢我抢不到的二次元周边!
+ Queue customers = new ArrayDeque<>(Arrays.asList("刑部尚书手工耿", "木瓜大盗大漠叔", "竹鼠发烧找华农", "朴实无华朱一旦"));
+ // 分组
+ List groups = Stream.iterate(0L, i -> ++i).limit(4).map(i -> Group.builder().id(i).build()).collect(Collectors.toList());
+ // 如你所见,它是一个map,key由用户id,value由用户组成
+ Map idUserMap = Stream.iterate(0L, i -> ++i).limit(4).map(i -> User.builder().id(i).name(customers.poll()).build()).collect(Collectors.toMap(User::getId, Function.identity()));
+ // 如你所见,它是一个map,key由分组id,value由用户ids组成,典型的多对多关系
+ Map> groupIdUserIdsMap = groups.stream().flatMap(group -> idUserMap.keySet().stream().map(userId -> UserGroup.builder().groupId(group.getId()).userId(userId).build())).collect(Collectors.groupingBy(UserGroup::getUserId, Collectors.mapping(UserGroup::getGroupId, Collectors.toList())));
+
+ // 神奇的魔法发生了, 分组id和用户ids组成的map,竟然变成了订单编号和用户实体集合组成的map
+ Map> groupIdUserMap = MapUtil.change(groupIdUserIdsMap, (groupId, userIds) -> userIds.stream().map(idUserMap::get).collect(Collectors.toList()));
+
+ // 然后你就可以拿着这个map,去封装groups,使其能够在订单数据带出客户信息啦
+ groups.forEach(group -> Opt.ofNullable(group.getId()).map(groupIdUserMap::get).ifPresent(group::setUsers));
+
+ // 下面是测试报告
+ groups.forEach(group -> {
+ List users = group.getUsers();
+ Assert.assertEquals("刑部尚书手工耿", users.get(0).getName());
+ Assert.assertEquals("木瓜大盗大漠叔", users.get(1).getName());
+ Assert.assertEquals("竹鼠发烧找华农", users.get(2).getName());
+ Assert.assertEquals("朴实无华朱一旦", users.get(3).getName());
+ });
+ // 能写代码真开心
+ }
+
@Test
public void filterMapWrapperTest() {
Map map = MapUtil.newHashMap();