From 2087ef8be7afe9cf555ff09419a7e48df7cb7008 Mon Sep 17 00:00:00 2001
From: VampireAchao <achao1441470436@gmail.com>
Date: Wed, 23 Mar 2022 19:01:45 +0800
Subject: [PATCH 1/3] =?UTF-8?q?=E6=96=B0=E5=A2=9ELambdaUtil#getImplClass?=
 =?UTF-8?q?=E6=96=B9=E6=B3=95?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../cn/hutool/core/lang/func/LambdaUtil.java  | 18 +++++++++++++----
 .../hutool/core/lang/func/LambdaUtilTest.java | 20 +++++++++++++++----
 2 files changed, 30 insertions(+), 8 deletions(-)

diff --git a/hutool-core/src/main/java/cn/hutool/core/lang/func/LambdaUtil.java b/hutool-core/src/main/java/cn/hutool/core/lang/func/LambdaUtil.java
index c57a41f47..a2566eebe 100644
--- a/hutool-core/src/main/java/cn/hutool/core/lang/func/LambdaUtil.java
+++ b/hutool-core/src/main/java/cn/hutool/core/lang/func/LambdaUtil.java
@@ -1,12 +1,14 @@
 package cn.hutool.core.lang.func;
 
-import cn.hutool.core.bean.BeanUtil;
-import cn.hutool.core.lang.SimpleCache;
-import cn.hutool.core.util.ReflectUtil;
-
 import java.io.Serializable;
 import java.lang.invoke.SerializedLambda;
 
+import cn.hutool.core.bean.BeanUtil;
+import cn.hutool.core.lang.SimpleCache;
+import cn.hutool.core.text.CharPool;
+import cn.hutool.core.util.ClassUtil;
+import cn.hutool.core.util.ReflectUtil;
+
 /**
  * Lambda相关工具类
  *
@@ -53,6 +55,10 @@ public class LambdaUtil {
 		return resolve(func).getImplMethodName();
 	}
 
+	public static <P> Class<P> getImplClass(Func1<P, ?> func) {
+		return ClassUtil.loadClass(resolve(func).getImplClass().replace(CharPool.SLASH, CharPool.DOT));
+	}
+
 	/**
 	 * 获取lambda表达式函数（方法）名称
 	 *
@@ -65,6 +71,10 @@ public class LambdaUtil {
 		return resolve(func).getImplMethodName();
 	}
 
+	public static <R> Class<R> getImplClass(Func0<?> func) {
+		return ClassUtil.loadClass(resolve(func).getImplClass().replace(CharPool.SLASH, CharPool.DOT));
+	}
+
 	/**
 	 * 获取lambda表达式Getter或Setter函数（方法）对应的字段名称，规则如下：
 	 * <ul>
diff --git a/hutool-core/src/test/java/cn/hutool/core/lang/func/LambdaUtilTest.java b/hutool-core/src/test/java/cn/hutool/core/lang/func/LambdaUtilTest.java
index b74a30a20..4c9697825 100644
--- a/hutool-core/src/test/java/cn/hutool/core/lang/func/LambdaUtilTest.java
+++ b/hutool-core/src/test/java/cn/hutool/core/lang/func/LambdaUtilTest.java
@@ -1,25 +1,37 @@
 package cn.hutool.core.lang.func;
 
-import lombok.Data;
 import org.junit.Assert;
 import org.junit.Test;
 
+import lombok.Data;
+
 public class LambdaUtilTest {
 
 	@Test
-	public void getMethodNameTest(){
+	public void getMethodNameTest() {
 		String methodName = LambdaUtil.getMethodName(MyTeacher::getAge);
 		Assert.assertEquals("getAge", methodName);
 	}
 
 	@Test
-	public void getFieldNameTest(){
+	public void getFieldNameTest() {
 		String fieldName = LambdaUtil.getFieldName(MyTeacher::getAge);
 		Assert.assertEquals("age", fieldName);
 	}
 
+	@Test
+	public void getImplClassTest() {
+		Class<MyTeacher> aClass = LambdaUtil.getImplClass(MyTeacher::getAge);
+		Assert.assertEquals(MyTeacher.class, aClass);
+
+		MyTeacher myTeacher = new MyTeacher();
+		Class<MyTeacher> bClass = LambdaUtil.getImplClass(myTeacher::getAge);
+		Assert.assertEquals(MyTeacher.class, bClass);
+	}
+
 	@Data
-	static class MyTeacher{
+	static class MyTeacher {
+
 		public String age;
 	}
 }

From c669426a1e03050ea7e53b3a88467975e721a5e8 Mon Sep 17 00:00:00 2001
From: VampireAchao <achao1441470436@gmail.com>
Date: Wed, 23 Mar 2022 22:27:38 +0800
Subject: [PATCH 2/3] =?UTF-8?q?=E4=BF=AE=E6=94=B9Func1=E5=8F=82=E6=95=B0?=
 =?UTF-8?q?=E7=9A=84=E6=96=B9=E6=B3=95=E4=B8=BALambdaUtil#getInstantiatedC?=
 =?UTF-8?q?lass=20=E6=8F=90=E4=BE=9BEnumUtil=E4=B8=AD=E5=AF=B9lambda?=
 =?UTF-8?q?=E8=BF=9B=E8=A1=8C=E6=98=A0=E5=B0=84=E5=A4=84=E7=90=86?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../cn/hutool/core/lang/func/LambdaUtil.java  | 27 +++++++++++---
 .../java/cn/hutool/core/util/EnumUtil.java    | 37 +++++++++++++++++--
 .../hutool/core/lang/func/LambdaUtilTest.java |  4 +-
 .../cn/hutool/core/util/EnumUtilTest.java     | 32 +++++++++++-----
 4 files changed, 81 insertions(+), 19 deletions(-)

diff --git a/hutool-core/src/main/java/cn/hutool/core/lang/func/LambdaUtil.java b/hutool-core/src/main/java/cn/hutool/core/lang/func/LambdaUtil.java
index a2566eebe..cfec37eea 100644
--- a/hutool-core/src/main/java/cn/hutool/core/lang/func/LambdaUtil.java
+++ b/hutool-core/src/main/java/cn/hutool/core/lang/func/LambdaUtil.java
@@ -1,13 +1,15 @@
 package cn.hutool.core.lang.func;
 
-import java.io.Serializable;
-import java.lang.invoke.SerializedLambda;
-
 import cn.hutool.core.bean.BeanUtil;
 import cn.hutool.core.lang.SimpleCache;
 import cn.hutool.core.text.CharPool;
+import cn.hutool.core.text.StrPool;
 import cn.hutool.core.util.ClassUtil;
 import cn.hutool.core.util.ReflectUtil;
+import cn.hutool.core.util.StrUtil;
+
+import java.io.Serializable;
+import java.lang.invoke.SerializedLambda;
 
 /**
  * Lambda相关工具类
@@ -55,8 +57,16 @@ public class LambdaUtil {
 		return resolve(func).getImplMethodName();
 	}
 
-	public static <P> Class<P> getImplClass(Func1<P, ?> func) {
-		return ClassUtil.loadClass(resolve(func).getImplClass().replace(CharPool.SLASH, CharPool.DOT));
+	/**
+	 * 获取lambda实现类
+	 *
+	 * @param func lambda
+	 * @param <P>  类型
+	 * @return lambda实现类
+	 */
+	public static <P> Class<P> getInstantiatedClass(Func1<P, ?> func) {
+		String instantiatedMethodType = resolve(func).getInstantiatedMethodType();
+		return ClassUtil.loadClass(StrUtil.replace(StrUtil.sub(instantiatedMethodType, 2, StrUtil.indexOf(instantiatedMethodType, ';')), StrPool.SLASH, StrPool.DOT));
 	}
 
 	/**
@@ -71,6 +81,13 @@ public class LambdaUtil {
 		return resolve(func).getImplMethodName();
 	}
 
+	/**
+	 * 获取lambda实现类
+	 *
+	 * @param func lambda
+	 * @param <R>  类型
+	 * @return lambda实现类
+	 */
 	public static <R> Class<R> getImplClass(Func0<?> func) {
 		return ClassUtil.loadClass(resolve(func).getImplClass().replace(CharPool.SLASH, CharPool.DOT));
 	}
diff --git a/hutool-core/src/main/java/cn/hutool/core/util/EnumUtil.java b/hutool-core/src/main/java/cn/hutool/core/util/EnumUtil.java
index 4a1365d9e..b7adbe0f1 100644
--- a/hutool-core/src/main/java/cn/hutool/core/util/EnumUtil.java
+++ b/hutool-core/src/main/java/cn/hutool/core/util/EnumUtil.java
@@ -1,13 +1,13 @@
 package cn.hutool.core.util;
 
 import cn.hutool.core.lang.Assert;
+import cn.hutool.core.lang.func.Func1;
+import cn.hutool.core.lang.func.LambdaUtil;
 import cn.hutool.core.map.MapUtil;
 
 import java.lang.reflect.Field;
-import java.util.ArrayList;
-import java.util.LinkedHashMap;
-import java.util.List;
-import java.util.Map;
+import java.util.*;
+import java.util.function.Function;
 
 /**
  * 枚举工具类
@@ -210,6 +210,35 @@ public class EnumUtil {
 		return names;
 	}
 
+
+	/**
+	 * 通过 某字段对应值 获取 枚举，获取不到时为 {@code null}
+	 *
+	 * @param condition 条件字段
+	 * @param value     条件字段值
+	 * @param <E>       枚举类型
+	 * @param <C>       字段类型
+	 * @return 对应枚举 ，获取不到时为 {@code null}
+	 */
+	public static <E extends Enum<E>, C> E getBy(Func1<E, C> condition, C value) {
+		return Arrays.stream(LambdaUtil.getInstantiatedClass(condition).getEnumConstants()).filter(e -> condition.callWithRuntimeException(e).equals(value)).findAny().orElse(null);
+	}
+
+	/**
+	 * 通过 某字段对应值 获取 枚举中另一字段值，获取不到时为 {@code null}
+	 *
+	 * @param field     你想要获取的字段
+	 * @param condition 条件字段
+	 * @param value     条件字段值
+	 * @param <E>       枚举类型
+	 * @param <F>       想要获取的字段类型
+	 * @param <C>       条件字段类型
+	 * @return 对应枚举中另一字段值 ，获取不到时为 {@code null}
+	 */
+	public static <E extends Enum<E>, F, C> F getFieldBy(Function<E, F> field, Func1<E, C> condition, C value) {
+		return Arrays.stream(LambdaUtil.getInstantiatedClass(condition).getEnumConstants()).filter(e -> condition.callWithRuntimeException(e).equals(value)).findAny().map(field).orElse(null);
+	}
+
 	/**
 	 * 获取枚举字符串值和枚举对象的Map对应，使用LinkedHashMap保证有序<br>
 	 * 结果中键为枚举名，值为枚举对象
diff --git a/hutool-core/src/test/java/cn/hutool/core/lang/func/LambdaUtilTest.java b/hutool-core/src/test/java/cn/hutool/core/lang/func/LambdaUtilTest.java
index 4c9697825..d78f385ee 100644
--- a/hutool-core/src/test/java/cn/hutool/core/lang/func/LambdaUtilTest.java
+++ b/hutool-core/src/test/java/cn/hutool/core/lang/func/LambdaUtilTest.java
@@ -21,9 +21,11 @@ public class LambdaUtilTest {
 
 	@Test
 	public void getImplClassTest() {
-		Class<MyTeacher> aClass = LambdaUtil.getImplClass(MyTeacher::getAge);
+		// 一般用于封装工具类时减少参数使用
+		Class<MyTeacher> aClass = LambdaUtil.getInstantiatedClass(MyTeacher::getAge);
 		Assert.assertEquals(MyTeacher.class, aClass);
 
+		// 一般用于封装工具类时减少参数使用
 		MyTeacher myTeacher = new MyTeacher();
 		Class<MyTeacher> bClass = LambdaUtil.getImplClass(myTeacher::getAge);
 		Assert.assertEquals(MyTeacher.class, bClass);
diff --git a/hutool-core/src/test/java/cn/hutool/core/util/EnumUtilTest.java b/hutool-core/src/test/java/cn/hutool/core/util/EnumUtilTest.java
index 555d8f644..d95d2d963 100644
--- a/hutool-core/src/test/java/cn/hutool/core/util/EnumUtilTest.java
+++ b/hutool-core/src/test/java/cn/hutool/core/util/EnumUtilTest.java
@@ -9,7 +9,7 @@ import java.util.Map;
 
 /**
  * EnumUtil单元测试
- * 
+ *
  * @author looly
  *
  */
@@ -20,39 +20,53 @@ public class EnumUtilTest {
 		List<String> names = EnumUtil.getNames(TestEnum.class);
 		Assert.assertEquals(CollUtil.newArrayList("TEST1", "TEST2", "TEST3"), names);
 	}
-	
+
 	@Test
 	public void getFieldValuesTest() {
 		List<Object> types = EnumUtil.getFieldValues(TestEnum.class, "type");
 		Assert.assertEquals(CollUtil.newArrayList("type1", "type2", "type3"), types);
 	}
-	
+
 	@Test
 	public void getFieldNamesTest() {
 		List<String> names = EnumUtil.getFieldNames(TestEnum.class);
 		Assert.assertTrue(names.contains("type"));
 		Assert.assertTrue(names.contains("name"));
 	}
-	
+
+	@Test
+	public void getByTest() {
+		// 枚举中字段互相映射使用
+		TestEnum testEnum = EnumUtil.getBy(TestEnum::getType, "type2");
+		Assert.assertEquals("TEST2", testEnum.name());
+	}
+
+	@Test
+	public void getFieldByTest() {
+		// 枚举中字段互相映射使用
+		String type = EnumUtil.getFieldBy(TestEnum::getType, TestEnum::ordinal, 1);
+		Assert.assertEquals("type2", type);
+	}
+
 	@Test
 	public void likeValueOfTest() {
 		TestEnum value = EnumUtil.likeValueOf(TestEnum.class, "type2");
 		Assert.assertEquals(TestEnum.TEST2, value);
 	}
-	
+
 	@Test
 	public void getEnumMapTest() {
 		Map<String,TestEnum> enumMap = EnumUtil.getEnumMap(TestEnum.class);
 		Assert.assertEquals(TestEnum.TEST1, enumMap.get("TEST1"));
 	}
-	
+
 	@Test
 	public void getNameFieldMapTest() {
 		Map<String, Object> enumMap = EnumUtil.getNameFieldMap(TestEnum.class, "type");
 		assert enumMap != null;
 		Assert.assertEquals("type1", enumMap.get("TEST1"));
 	}
-	
+
 	public enum TestEnum{
 		TEST1("type1"), TEST2("type2"), TEST3("type3");
 
@@ -62,11 +76,11 @@ public class EnumUtilTest {
 
 		private final String type;
 		private String name;
-		
+
 		public String getType() {
 			return this.type;
 		}
-		
+
 		public String getName() {
 			return this.name;
 		}

From 38df5a48b650f8c268b70ea42ed8c044fe6d8657 Mon Sep 17 00:00:00 2001
From: VampireAchao <achao1441470436@gmail.com>
Date: Thu, 24 Mar 2022 23:33:34 +0800
Subject: [PATCH 3/3] =?UTF-8?q?=E6=96=B0=E5=A2=9EMapUtil#change=E5=87=BD?=
 =?UTF-8?q?=E6=95=B0?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../main/java/cn/hutool/core/map/MapUtil.java | 23 +++++-
 .../java/cn/hutool/core/map/MapUtilTest.java  | 74 ++++++++++++++++++-
 2 files changed, 94 insertions(+), 3 deletions(-)

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<br>
+	 * 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 <K>        {@code key}的类型
+	 * @param <V>        {@code value}的类型
+	 * @param <R>        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 <K, V, R> Map<K, R> change(Map<K, V> map, BiFunction<K, V, R> 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<User> users;
+	}
+
+	@Data
+	@Builder
+	public static class UserGroup {
+		private Long userId;
+		private Long groupId;
+	}
+
+
 	@Test
 	public void filterTest() {
 		Map<String, String> 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<Integer, String> adjectivesMap = MapUtil.<Integer, String>builder()
+				.put(0, "lovely")
+				.put(1, "friendly")
+				.put(2, "happily")
+				.build();
+
+		Map<Integer, String> 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<String> 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<Group> 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<Long, User> 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<Long, List<Long>> 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<Long, List<User>> 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<User> 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<String, String> map = MapUtil.newHashMap();