!583 MapUtil提供change函数，EnumUtil提供getBy函数，通过lambda进行枚举字段映射

Merge pull request !583 from 阿超/v5-dev

hutool-core/src/test/java/cn/hutool/core/lang/func/LambdaUtilTest.java

@@ -1,25 +1,39 @@
 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() {
+		// 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);
+	}
+
 	@Data
-	static class MyTeacher{
+	static class MyTeacher {
+
 		public String age;
 	}
 }

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();

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;
 		}