重构增强流：

1.移除SimpleStreamWrapper;
2.将EasyStream中部分方法移动至接口中;
3.调整类名、方法名、变量名与部分注释;
4.为实例方法添加空值校验;
5.补充测试用例;

hutool-core/src/test/java/cn/hutool/core/stream/AbstractEnhancedWrappedStreamTest.java

@@ -0,0 +1,705 @@
+package cn.hutool.core.stream;
+
+import cn.hutool.core.collection.ListUtil;
+import lombok.AllArgsConstructor;
+import lombok.Getter;
+import lombok.Setter;
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.util.*;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.function.Function;
+import java.util.stream.*;
+
+import static java.util.Arrays.asList;
+import static java.util.Collections.singletonList;
+
+/**
+ * {@link AbstractEnhancedWrappedStream}、{@link TerminableWrappedStream}、{@link TransformableWrappedStream}的测试用例。
+ * 此用例用于保证通过{@link AbstractEnhancedWrappedStream}获得的默认方法，在子类不重写的情况下能够按照预期效果生效
+ *
+ * @author huangchengxing
+ */
+public class AbstractEnhancedWrappedStreamTest {
+
+	@Test
+	public void testToList() {
+		List<Integer> list = asList(1, 2, 3);
+		List<Integer> toList = wrap(list).toList();
+		Assert.assertEquals(list, toList);
+	}
+
+	@Test
+	public void testToUnmodifiableList() {
+		List<Integer> list = wrap(1, 2, 3)
+			.toUnmodifiableList();
+		Assert.assertThrows(UnsupportedOperationException.class, () -> list.remove(0));
+	}
+
+	@Test
+	public void testToSet() {
+		List<Integer> list = asList(1, 2, 3);
+		Set<String> toSet = wrap(list).map(String::valueOf).toSet();
+		Assert.assertEquals(new HashSet<>(asList("1", "2", "3")), toSet);
+	}
+
+	@Test
+	public void testToUnmodifiableSet() {
+		Set<Integer> set = wrap(1, 2, 3)
+			.toUnmodifiableSet();
+		Assert.assertThrows(UnsupportedOperationException.class, () -> set.remove(0));
+	}
+
+	@Test
+	public void testToCollection() {
+		List<Integer> list = asList(1, 2, 3);
+		List<String> toCollection = wrap(list).map(String::valueOf).toColl(LinkedList::new);
+		Assert.assertEquals(asList("1", "2", "3"), toCollection);
+	}
+
+	@Test
+	public void testToMap() {
+		List<Integer> list = asList(1, 2, 3);
+		Map<String, Integer> identityMap = wrap(list).toMap(String::valueOf);
+		Assert.assertEquals(new HashMap<String, Integer>() {{
+			put("1", 1);
+			put("2", 2);
+			put("3", 3);
+		}}, identityMap);
+	}
+
+	@Test
+	public void testToUnmodifiableMap() {
+		Map<Integer, Integer> map1 = wrap(1, 2, 3).toUnmodifiableMap(Function.identity(), Function.identity());
+		Assert.assertThrows(UnsupportedOperationException.class, () -> map1.remove(1));
+		Map<Integer, Integer> map2 = wrap(1, 2, 3).toUnmodifiableMap(Function.identity(), Function.identity(), (t1, t2) -> t1);
+		Assert.assertThrows(UnsupportedOperationException.class, () -> map2.remove(1));
+	}
+
+	@Test
+	public void testToZip() {
+		List<Integer> orders = asList(1, 2, 3);
+		List<String> list = asList("dromara", "hutool", "sweet");
+		Map<Integer, String> toZip = wrap(orders).toZip(list);
+		Assert.assertEquals(new HashMap<Integer, String>() {{
+			put(1, "dromara");
+			put(2, "hutool");
+			put(3, "sweet");
+		}}, toZip);
+	}
+
+	@Test
+	public void testTransform() {
+		List<Integer> list = wrap(1, 2, 3).transform(Wrapper::toList).orElse(null);
+		Assert.assertEquals(asList(1, 2, 3), list);
+	}
+
+	@Test
+	public void testFindFirst() {
+		List<Integer> list = asList(1, 2, 3);
+		Assert.assertEquals((Integer)1, wrap(list).findFirst(t -> (t & 1) == 1).orElse(null));
+		Assert.assertEquals((Integer)1, wrap(list).filter(t -> (t & 1) == 1).findFirst().orElse(null));
+	}
+
+	@Test
+	public void testFindFirstIdx() {
+		List<Integer> list = asList(1, 2, 3);
+		Assert.assertEquals(1, wrap(list).findFirstIdx(t -> (t & 1) == 0));
+	}
+
+	@Test
+	public void testFindLast() {
+		List<Integer> list = asList(1, 2, 3);
+		Assert.assertEquals((Integer)3, wrap(list).findLast(t -> (t & 1) == 1).orElse(null));
+	}
+
+	@Test
+	public void testFindLastIdx() {
+		List<Integer> list = asList(1, 2, 3);
+		Assert.assertEquals(1, wrap(list).findLastIdx(t -> (t & 1) == 0));
+	}
+
+	@Test
+	public void testAt() {
+		List<Integer> list = asList(1, 2, 3);
+		Assert.assertEquals((Integer)3, wrap(list).at(2).orElse(null));
+	}
+
+	@Test
+	public void testIsEmpty() {
+		Assert.assertTrue(wrap(Collections.emptyList()).isEmpty());
+		Assert.assertFalse(wrap(asList(1, 2, 3)).isEmpty());
+	}
+
+	@Test
+	public void testIsNotEmpty() {
+		Assert.assertFalse(wrap(Collections.emptyList()).isNotEmpty());
+		Assert.assertTrue(wrap(asList(1, 2, 3)).isNotEmpty());
+	}
+
+	@Test
+	public void testJoining() {
+		List<Integer> list = asList(1, 2, 3);
+		String joining = wrap(list).join();
+		Assert.assertEquals("123", joining);
+		Assert.assertEquals("1,2,3", wrap(list).join(","));
+		Assert.assertEquals("(1,2,3)", wrap(list).join(",", "(", ")"));
+	}
+
+	@Test
+	public void testGrouping() {
+		List<Integer> list = asList(1, 2, 3);
+		Map<String, List<Integer>> map = new HashMap<String, List<Integer>>() {{
+			put("1", singletonList(1));
+			put("2", singletonList(2));
+			put("3", singletonList(3));
+		}};
+
+		Map<String, List<Integer>> group = wrap(list).group(String::valueOf, HashMap::new, Collectors.toList());
+		Assert.assertEquals(map, group);
+		group = wrap(list).group(String::valueOf, Collectors.toList());
+		Assert.assertEquals(map, group);
+		group = wrap(list).group(String::valueOf);
+		Assert.assertEquals(map, group);
+	}
+
+	@Test
+	public void testPartitioning() {
+		List<Integer> list = asList(1, 2, 3);
+		Map<Boolean, List<Integer>> map = new HashMap<Boolean, List<Integer>>() {{
+			put(Boolean.TRUE, singletonList(2));
+			put(Boolean.FALSE, asList(1, 3));
+		}};
+
+		Map<Boolean, List<Integer>> partition = wrap(list).partitioning(t -> (t & 1) == 0, Collectors.toList());
+		Assert.assertEquals(map, partition);
+		partition = wrap(list).partitioning(t -> (t & 1) == 0);
+		Assert.assertEquals(map, partition);
+	}
+
+	@Test
+	public void testForEachIdx() {
+		List<Integer> elements = new ArrayList<>();
+		List<Integer> indexes = new ArrayList<>();
+		wrap(1, 2, 3).forEachIdx((t, i) -> {
+			elements.add(t);
+			indexes.add(i);
+		});
+		Assert.assertEquals(asList(1, 2, 3), elements);
+		Assert.assertEquals(asList(0, 1, 2), indexes);
+	}
+
+	@Test
+	public void testForEachOrderedIdx() {
+		List<Integer> elements = new ArrayList<>();
+		List<Integer> indexes = new ArrayList<>();
+		wrap(1, 2, 3).forEachOrderedIdx((t, i) -> {
+			elements.add(t);
+			indexes.add(i);
+		});
+		Assert.assertEquals(asList(1, 2, 3), elements);
+		Assert.assertEquals(asList(0, 1, 2), indexes);
+	}
+
+	@Test
+	public void testForEachOrdered() {
+		List<Integer> elements = new ArrayList<>();
+		wrap(1, 2, 3).forEachOrdered(elements::add);
+		Assert.assertEquals(asList(1, 2, 3), elements);
+	}
+
+	@Test
+	public void testForEach() {
+		List<Integer> elements = new ArrayList<>();
+		wrap(1, 2, 3).forEach(elements::add);
+		Assert.assertEquals(asList(1, 2, 3), elements);
+	}
+
+	@Test
+	public void testMapToInt() {
+		int[] array = wrap(1, 2, 3).mapToInt(Integer::intValue).toArray();
+		Assert.assertArrayEquals(new int[] {1, 2, 3}, array);
+	}
+
+	@Test
+	public void testMapToLong() {
+		long[] array = wrap(1L, 2L, 3L).mapToLong(Long::intValue).toArray();
+		Assert.assertArrayEquals(new long[] {1L, 2L, 3L}, array);
+	}
+
+	@Test
+	public void testMapToDouble() {
+		double[] array = wrap(1d, 2d, 3d).mapToDouble(Double::intValue).toArray();
+		Assert.assertEquals(1d, array[0], 0.01);
+		Assert.assertEquals(2d, array[1], 0.01);
+		Assert.assertEquals(3d, array[2], 0.01);
+	}
+
+	@Test
+	public void testFlatMapToInt() {
+		int[] array = wrap(1, 2, 3).flatMapToInt(IntStream::of).toArray();
+		Assert.assertArrayEquals(new int[] {1, 2, 3}, array);
+	}
+
+	@Test
+	public void testFlatMapToLong() {
+		long[] array = wrap(1L, 2L, 3L).flatMapToLong(LongStream::of).toArray();
+		Assert.assertArrayEquals(new long[] {1L, 2L, 3L}, array);
+	}
+
+	@Test
+	public void testFlatMapToDouble() {
+		double[] array = wrap(1d, 2d, 3d).flatMapToDouble(DoubleStream::of).toArray();
+		Assert.assertEquals(1d, array[0], 0.01);
+		Assert.assertEquals(2d, array[1], 0.01);
+		Assert.assertEquals(3d, array[2], 0.01);
+	}
+
+	@Test
+	public void testSorted() {
+		List<Integer> list = wrap(3, 1, 2).sorted().toList();
+		Assert.assertEquals(asList(1, 2, 3), list);
+	}
+
+	@Test
+	public void testPeek() {
+		List<Integer> elements = new ArrayList<>();
+		wrap(1, 2, 3).peek(elements::add).exec();
+		Assert.assertEquals(asList(1, 2, 3), elements);
+	}
+
+	@Test
+	public void testPeekIdx() {
+		List<Integer> elements = new ArrayList<>();
+		List<Integer> indexes = new ArrayList<>();
+		wrap(1, 2, 3).peekIdx((t, i) -> {
+			elements.add(t);
+			indexes.add(i);
+		}).exec();
+		Assert.assertEquals(asList(1, 2, 3), elements);
+		Assert.assertEquals(asList(0, 1, 2), indexes);
+
+		Set<Integer> elements2 = new HashSet<>();
+		Set<Integer> indexes2 = new HashSet<>();
+		wrap(1, 2, null).parallel().peekIdx((t, i) -> {
+			elements2.add(t);
+			indexes2.add(i);
+		}).exec();
+		Assert.assertEquals(new HashSet<>(asList(1, null, 2)), elements2);
+		Assert.assertEquals(new HashSet<>(asList(-1, -1, -1)), indexes2);
+	}
+
+	@Test
+	public void testLimit() {
+		List<Integer> list = wrap(1, 2, 3).limit(2L).toList();
+		Assert.assertEquals(asList(1, 2), list);
+	}
+
+	@Test
+	public void testSkip() {
+		List<Integer> list = wrap(1, 2, 3).skip(1L).toList();
+		Assert.assertEquals(asList(2, 3), list);
+	}
+
+	@Test
+	public void testToArray() {
+		Object[] array1 = wrap(1, 2, 3).toArray();
+		Assert.assertArrayEquals(new Object[]{1, 2, 3}, array1);
+		array1 = wrap(1, 2, 3).toArray(Object[]::new);
+		Assert.assertArrayEquals(new Object[]{1, 2, 3}, array1);
+	}
+
+	@Test
+	public void testReduce() {
+		Assert.assertEquals((Integer)6, wrap(1, 2, 3).reduce(Integer::sum).orElse(null));
+		Assert.assertEquals((Integer)6, wrap(1, 2, 3).reduce(0, Integer::sum));
+		Assert.assertEquals((Integer)6, wrap(1, 2, 3).reduce(0, Integer::sum, Integer::sum));
+	}
+
+	@Test
+	public void testCollect() {
+		Assert.assertEquals(asList(1, 2, 3), wrap(1, 2, 3).collect(Collectors.toList()));
+		Assert.assertEquals(
+			asList(1, 2, 3),
+			wrap(1, 2, 3).collect(ArrayList::new, List::add, List::addAll)
+		);
+	}
+
+	@Test
+	public void testMin() {
+		Assert.assertEquals((Integer)1, wrap(1, 2, 3).min(Comparator.comparingInt(Integer::intValue)).orElse(null));
+	}
+
+	@Test
+	public void testMax() {
+		Assert.assertEquals((Integer)3, wrap(1, 2, 3).max(Comparator.comparingInt(Integer::intValue)).orElse(null));
+	}
+
+	@Test
+	public void testCount() {
+		Assert.assertEquals(3, wrap(1, 2, 3).count());
+	}
+
+	@Test
+	public void testAnyMatch() {
+		Assert.assertTrue(wrap(1, 2, 3).anyMatch(t -> (t & 1) == 0));
+		Assert.assertFalse(wrap(1, 3).anyMatch(t -> (t & 1) == 0));
+	}
+
+	@Test
+	public void testAllMatch() {
+		Assert.assertFalse(wrap(1, 2, 3).allMatch(t -> (t & 1) == 0));
+		Assert.assertTrue(wrap(2, 4).anyMatch(t -> (t & 1) == 0));
+	}
+
+	@Test
+	public void testNoneMatch() {
+		Assert.assertFalse(wrap(1, 2, 3).noneMatch(t -> (t & 1) == 0));
+		Assert.assertTrue(wrap(1, 3).noneMatch(t -> (t & 1) == 0));
+	}
+
+	@Test
+	public void testFindAny() {
+		Assert.assertNotNull(wrap(1, 2, 3).findAny());
+	}
+
+	@Test
+	public void testIterator() {
+		Iterator<Integer> iter1 = Stream.of(1, 2, 3).iterator();
+		Iterator<Integer> iter2 = wrap(1, 2, 3).iterator();
+		while (iter1.hasNext() && iter2.hasNext()) {
+			Assert.assertEquals(iter1.next(), iter2.next());
+		}
+	}
+
+	@Test
+	public void testSpliterator() {
+		Spliterator<Integer> iter1 = Stream.of(1, 2, 3).spliterator();
+		Spliterator<Integer> iter2 = wrap(1, 2, 3).spliterator();
+			Assert.assertEquals(iter1.trySplit().estimateSize(), iter2.trySplit().estimateSize());
+	}
+
+	@Test
+	public void testIsParallel() {
+		Assert.assertTrue(wrap(Stream.of(1, 2, 3).parallel()).isParallel());
+	}
+
+	@Test
+	public void testSequential() {
+		Assert.assertFalse(wrap(Stream.of(1, 2, 3).parallel()).sequential().isParallel());
+	}
+
+	@Test
+	public void testUnordered() {
+		Assert.assertNotNull(wrap(Stream.of(1, 2, 3)).unordered());
+	}
+
+	@Test
+	public void testOnClose() {
+		AtomicBoolean atomicBoolean = new AtomicBoolean(false);
+		wrap(Stream.of(1, 2, 3).onClose(() -> atomicBoolean.set(true))).close();
+		Assert.assertTrue(atomicBoolean.get());
+	}
+
+	@Test
+	public void testClose() {
+		Wrapper<Integer> stream = wrap(Stream.of(1, 2, 3));
+		stream.close();
+		Assert.assertThrows(IllegalStateException.class, stream::exec);
+	}
+
+	@Test
+	public void testReverse() {
+		Assert.assertEquals(
+			asList(3, 2, 1), wrap(1, 2, 3).reverse().toList()
+		);
+	}
+
+	@Test
+	public void testParallel() {
+		Assert.assertTrue(wrap(1, 2, 3).parallel().isParallel());
+	}
+
+	@Test
+	public void testSplice() {
+		Assert.assertEquals(
+			asList(1, 4, 5), wrap(1, 2, 3).splice(1, 2, 4, 5).toList()
+		);
+	}
+
+	@Test
+	public void testTakeWhile() {
+		Assert.assertEquals(
+			asList(1, 2),
+			wrap(1, 2, 3, 4).takeWhile(i -> !Objects.equals(i, 3)).toList()
+		);
+
+	}
+
+	@Test
+	public void testDropWhile() {
+		Assert.assertEquals(
+			asList(3, 4),
+			wrap(1, 2, 3, 4).dropWhile(i -> !Objects.equals(i, 3)).toList()
+		);
+	}
+
+	@Test
+	public void testDistinct() {
+		Assert.assertEquals(
+			asList(1, 2, 3), wrap(1, 1, 2, 3).distinct().toList()
+		);
+	}
+
+	@Test
+	public void testLog() {
+		Assert.assertNotNull(wrap(1, 2, 3).log().toList());
+	}
+
+	@Test
+	public void testPush() {
+		Assert.assertEquals(
+			asList(1, 2, 3), wrap(1).push(2, 3).toList()
+		);
+	}
+
+	@Test
+	public void testUnshift() {
+		Assert.assertEquals(
+			asList(1, 2, 3), wrap(3).unshift(1, 2).toList()
+		);
+	}
+
+	@Test
+	public void testAppend() {
+		Assert.assertEquals(
+			asList(1, 2, 3), wrap(1).append(asList(2, 3)).toList()
+		);
+		Assert.assertEquals(
+			asList(1, 2, 3), wrap(1, 2, 3).append(null).toList()
+		);
+	}
+
+	@Test
+	public void testPrepend() {
+		Assert.assertEquals(
+			asList(1, 2, 3), wrap(3).prepend(asList(1, 2)).toList()
+		);
+		Assert.assertEquals(
+			asList(1, 2, 3), wrap(1, 2, 3).prepend(null).toList()
+		);
+	}
+
+	@Test
+	public void testNonNull() {
+		Assert.assertEquals(
+			asList(1, 3), wrap(1, null, 3).nonNull().toList()
+		);
+	}
+
+	@Test
+	public void testFilterIdx() {
+		List<Integer> indexes = new ArrayList<>();
+		Assert.assertEquals(
+			asList(1, 3),
+			wrap(1, 2, 3).filterIdx((t, i) -> {
+				indexes.add(i);
+				return (t & 1) == 1;
+			}).toList()
+		);
+		Assert.assertEquals(asList(0, 1, 2), indexes);
+	}
+
+	@Test
+	public void testFilter() {
+		Assert.assertEquals(
+			asList(1, 3), wrap(1, 2, 3).filter(i -> (i & 1) == 1).toList()
+		);
+	}
+
+	@Test
+	public void testFlatMap() {
+		Assert.assertEquals(
+			asList(1, 2, 3), wrap(1, 2, 3).flatMap(Stream::of).toList()
+		);
+	}
+
+	@Test
+	public void testFlatMapIdx() {
+		List<Integer> indexes = new ArrayList<>();
+		Assert.assertEquals(
+			asList(1, 2, 3), wrap(1, 2, 3).flatMapIdx((t, i) -> {
+				indexes.add(i);
+				return Stream.of(t);
+			}).toList()
+		);
+		Assert.assertEquals(asList(0, 1, 2), indexes);
+	}
+
+	@Test
+	public void testFlat() {
+		Assert.assertEquals(
+			asList(1, 2, 3), wrap(1, 2, 3).flat(Collections::singletonList).toList()
+		);
+	}
+
+	@Test
+	public void testFlatNonNull() {
+		Assert.assertEquals(
+			asList(2, 3), wrap(null, 2, 3).flatNonNull(Collections::singletonList).toList()
+		);
+	}
+
+	@Test
+	public void testFlatTree() {
+		Tree root = new Tree(1, asList(new Tree(2, asList(new Tree(3, Collections.emptyList())))));
+		Assert.assertEquals(3L, wrap(root).flatTree(Tree::getChildren, Tree::setChildren).count());
+	}
+
+	@Test
+	public void testMap() {
+		Assert.assertEquals(
+			asList("1", "2", "3"), wrap(1, 2, 3).map(String::valueOf).toList()
+		);
+	}
+
+	@Test
+	public void testMapNonNull() {
+		Assert.assertEquals(
+			asList("3"), wrap(null, 2, 3, 4).mapNonNull(t -> ((t & 1) == 0) ? null : String.valueOf(t)).toList()
+		);
+	}
+
+	@Test
+	public void testMapIdx() {
+		List<Integer> indexes = new ArrayList<>();
+		Assert.assertEquals(
+			asList("1", "2", "3"), wrap(1, 2, 3).mapIdx((t, i) -> {
+				indexes.add(i);
+				return String.valueOf(t);
+			}).toList()
+		);
+		Assert.assertEquals(asList(0, 1, 2), indexes);
+	}
+
+	@Test
+	public void testMapMulti() {
+		Assert.assertEquals(
+			asList(1, 2, 3),
+			wrap(1, 2, 3).mapMulti((t, builder) -> {
+				builder.accept(t);
+			}).toList()
+		);
+	}
+
+	@Test
+	public void testHashCode() {
+		Stream<Integer> stream = Stream.of(1, 2, 3);
+		Assert.assertEquals(stream.hashCode(), wrap(stream).hashCode());
+	}
+
+	@Test
+	public void testEquals() {
+		Stream<Integer> stream = Stream.of(1, 2, 3);
+		Assert.assertEquals(wrap(stream), stream);
+	}
+
+	@Test
+	public void testToString() {
+		Stream<Integer> stream = Stream.of(1, 2, 3);
+		Assert.assertEquals(stream.toString(), wrap(stream).toString());
+	}
+
+	@Test
+	public void testToEntries() {
+		Map<Integer, Integer> expect = new HashMap<Integer, Integer>(){{
+			put(1, 1);
+			put(2, 2);
+			put(3, 3);
+		}};
+		Map<Integer, Integer> map = EasyStream.of(1, 2, 3)
+			.toEntries(Function.identity(), Function.identity())
+			.toMap();
+		Assert.assertEquals(expect, map);
+
+		map = EasyStream.of(1, 2, 3)
+			.toEntries(Function.identity())
+			.toMap();
+		Assert.assertEquals(expect, map);
+	}
+
+	@Test
+	public void testZip() {
+		final List<Integer> orders = Arrays.asList(1, 2, 3);
+		final List<String> list = Arrays.asList("dromara", "hutool", "sweet");
+		List<String> zip = wrap(orders).zip(list, (e1, e2) -> e1 + "." + e2).toList();
+		Assert.assertEquals(Arrays.asList("1.dromara", "2.hutool", "3.sweet"), zip);
+
+		zip = wrap((Stream<? extends Object>)EasyStream.iterate(1, i -> i + 1)).zip(list, (e1, e2) -> e1 + "." + e2).toList();
+		Assert.assertEquals(Arrays.asList("1.dromara", "2.hutool", "3.sweet"), zip);
+	}
+
+	@Test
+	public void testListSplit() {
+		final List<Integer> list = Arrays.asList(1, 2, 3, 4, 5);
+		List<List<Integer>> lists = wrap(list).split(2).map(TerminableWrappedStream::toList).toList();
+		Assert.assertEquals(ListUtil.split(list, 2), lists);
+
+		// 指定长度 大于等于 列表长度
+		lists = wrap(list).split(list.size()).map(TerminableWrappedStream::toList).toList();
+		Assert.assertEquals(singletonList(list), lists);
+	}
+
+	@Test
+	public void testSplitList() {
+		final List<Integer> list = Arrays.asList(1, 2, 3, 4, 5);
+		List<List<Integer>> lists = wrap(list).splitList(2).toList();
+		Assert.assertEquals(ListUtil.split(list, 2), lists);
+
+		// 指定长度 大于等于 列表长度
+		lists = wrap(list).splitList(list.size()).toList();
+		Assert.assertEquals(singletonList(list), lists);
+	}
+
+	@SafeVarargs
+	private static <T> Wrapper<T> wrap(T... array) {
+		return new Wrapper<>(Stream.of(array));
+	}
+
+	private static <T> Wrapper<T> wrap(Iterable<T> iterable) {
+		return new Wrapper<>(StreamSupport.stream(iterable.spliterator(), false));
+	}
+
+	private static <T> Wrapper<T> wrap(Stream<T> stream) {
+		return new Wrapper<>(stream);
+	}
+
+	private static class Wrapper<T> extends AbstractEnhancedWrappedStream<T, Wrapper<T>> {
+
+		/**
+		 * 创建一个流包装器
+		 *
+		 * @param stream 包装的流对象
+		 * @throws NullPointerException 当{@code stream}为{@code null}时抛出
+		 */
+		protected Wrapper(Stream<T> stream) {
+			super(stream);
+		}
+
+		@Override
+		public Wrapper<T> wrapping(Stream<T> source) {
+			return new Wrapper<>(source);
+		}
+
+	}
+
+	@Setter
+	@Getter
+	@AllArgsConstructor
+	private static class Tree {
+		private final Integer id;
+		private List<Tree> children;
+	}
+
+}

hutool-core/src/test/java/cn/hutool/core/stream/EasyStreamTest.java

@@ -1,9 +1,7 @@
 package cn.hutool.core.stream;
 
-
 import cn.hutool.core.collection.ListUtil;
 import cn.hutool.core.map.MapUtil;
-import lombok.Builder;
 import lombok.Data;
 import lombok.experimental.Tolerate;
 import org.junit.Assert;
@@ -22,6 +20,13 @@ import static java.util.Collections.singletonList;
  */
 public class EasyStreamTest {
 
+	@Test
+	public void testConcat() {
+		Stream<Integer> stream1 = Stream.of(1, 2);
+		Stream<Integer> stream2 = Stream.of(3, 4);
+		Assert.assertEquals(4, EasyStream.concat(stream1, stream2).count());
+	}
+
 	@Test
 	public void testBuilder() {
 		final List<Integer> list = EasyStream.<Integer>builder().add(1).add(2).add(3).build().toList();
@@ -54,7 +59,7 @@ public class EasyStreamTest {
 	}
 
 	@Test
-	public void testToCollection() {
+	public void testToColl() {
 		final List<Integer> list = Arrays.asList(1, 2, 3);
 		final List<String> toCollection = EasyStream.of(list).map(String::valueOf).toColl(LinkedList::new);
 		Assert.assertEquals(Arrays.asList("1", "2", "3"), toCollection);
@@ -168,18 +173,22 @@ public class EasyStreamTest {
 		final List<Integer> collect1 = list.stream().distinct().collect(Collectors.toList());
 		final List<Integer> collect2 = list.stream().parallel().distinct().collect(Collectors.toList());
 
-		// 使用FastStream去重
+		// 使用EasyStream去重
 		final List<Integer> distinctBy1 = EasyStream.of(list).distinct().toList();
 		final List<Integer> distinctBy2 = EasyStream.of(list).parallel().distinct(String::valueOf).toList();
 
 		Assert.assertEquals(collect1, distinctBy1);
 		Assert.assertEquals(collect2, distinctBy2);
+
+		Assert.assertEquals(
+			4, EasyStream.of(1, 2, 2, null, 3, null).parallel(true).distinct(t -> Objects.isNull(t) ? null : t.toString()).count()
+		);
 	}
 
 	@Test
 	public void testForeachIdx() {
 		final List<String> list = Arrays.asList("dromara", "hutool", "sweet");
-		final EasyStream.FastStreamBuilder<String> builder = EasyStream.builder();
+		final EasyStream.Builder<String> builder = EasyStream.builder();
 		EasyStream.of(list).forEachIdx((e, i) -> builder.accept(i + 1 + "." + e));
 		Assert.assertEquals(Arrays.asList("1.dromara", "2.hutool", "3.sweet"), builder.build().toList());
 		// 并行流时为-1
@@ -189,11 +198,11 @@ public class EasyStreamTest {
 	@Test
 	public void testForEachOrderedIdx() {
 		final List<String> list = Arrays.asList("dromara", "hutool", "sweet");
-		final EasyStream.FastStreamBuilder<String> builder = EasyStream.builder();
+		final EasyStream.Builder<String> builder = EasyStream.builder();
 		EasyStream.of(list).forEachOrderedIdx((e, i) -> builder.accept(i + 1 + "." + e));
 		Assert.assertEquals(Arrays.asList("1.dromara", "2.hutool", "3.sweet"), builder.build().toList());
 
-		final EasyStream.FastStreamBuilder<String> streamBuilder = EasyStream.builder();
+		final EasyStream.Builder<String> streamBuilder = EasyStream.builder();
 		EasyStream.of(list).parallel().forEachOrderedIdx((e, i) -> streamBuilder.accept(i + 1 + "." + e));
 		Assert.assertEquals(Arrays.asList("0.dromara", "0.hutool", "0.sweet"), streamBuilder.build().toList());
 
@@ -360,39 +369,6 @@ public class EasyStreamTest {
 		Assert.assertEquals(ListUtil.of((Object) null), EasyStream.of((Object) null).reverse().toList());
 	}
 
-	@Test
-	public void testZip() {
-		final List<Integer> orders = Arrays.asList(1, 2, 3);
-		final List<String> list = Arrays.asList("dromara", "hutool", "sweet");
-		List<String> zip = EasyStream.of(orders).zip(list, (e1, e2) -> e1 + "." + e2).toList();
-		Assert.assertEquals(Arrays.asList("1.dromara", "2.hutool", "3.sweet"), zip);
-
-		zip = EasyStream.iterate(1, i -> i + 1).zip(list, (e1, e2) -> e1 + "." + e2).toList();
-		Assert.assertEquals(Arrays.asList("1.dromara", "2.hutool", "3.sweet"), zip);
-	}
-
-	@Test
-	public void testListSplit() {
-		final List<Integer> list = Arrays.asList(1, 2, 3, 4, 5);
-		List<List<Integer>> lists = EasyStream.of(list).split(2).map(EasyStream::toList).toList();
-		Assert.assertEquals(ListUtil.split(list, 2), lists);
-
-		// 指定长度 大于等于 列表长度
-		lists = EasyStream.of(list).split(list.size()).map(EasyStream::toList).toList();
-		Assert.assertEquals(singletonList(list), lists);
-	}
-
-	@Test
-	public void testSplitList() {
-		final List<Integer> list = Arrays.asList(1, 2, 3, 4, 5);
-		List<List<Integer>> lists = EasyStream.of(list).splitList(2).toList();
-		Assert.assertEquals(ListUtil.split(list, 2), lists);
-
-		// 指定长度 大于等于 列表长度
-		lists = EasyStream.of(list).splitList(list.size()).toList();
-		Assert.assertEquals(singletonList(list), lists);
-	}
-
 	@Test
 	public void testTakeWhile() {
 		// 1 到 10
@@ -557,7 +533,7 @@ public class EasyStreamTest {
 	}
 
 	@Data
-	@Builder
+	@lombok.Builder
 	public static class Student {
 		private String name;
 		private Integer age;

hutool-core/src/test/java/cn/hutool/core/stream/EntryStreamTest.java

@@ -31,6 +31,17 @@ public class EntryStreamTest {
 			EntryStream.merge(Arrays.asList(1, 2), Arrays.asList(1, 2, 3))
 				.collectKeys(Collectors.toList())
 		);
+
+		Assert.assertEquals(
+			Arrays.asList(1, 2),
+			EntryStream.merge(null, Arrays.asList(1, 2))
+				.collectValues(Collectors.toList())
+		);
+		Assert.assertEquals(
+			Arrays.asList(1, 2),
+			EntryStream.merge(Arrays.asList(1, 2), null)
+				.collectKeys(Collectors.toList())
+		);
 	}
 
 	@Test
@@ -38,15 +49,21 @@ public class EntryStreamTest {
 		Map<String, String> map = new HashMap<>();
 		map.put("1", "1");
 		Assert.assertEquals(1, EntryStream.of(map).count());
+		Assert.assertEquals(0, EntryStream.of((Map<String, String>)null).count());
 
 		Set<Map.Entry<Integer, Integer>> entries = new HashSet<>();
 		entries.add(new Entry<>(1, 1));
 		entries.add(null);
 		Assert.assertEquals(2, EntryStream.of(entries).count());
+		Assert.assertEquals(0, EntryStream.of((Set<Map.Entry<Integer, Integer>>)null).count());
 		Assert.assertEquals(2, EntryStream.of(entries.stream()).count());
+		Assert.assertEquals(0, EntryStream.of((Stream<Map.Entry<Integer, Integer>>)null).count());
+		Assert.assertEquals(2, new EntryStream<>(entries.stream()).count());
+		Assert.assertThrows(NullPointerException.class, () -> new EntryStream<>(null));
 
 		Iterable<Integer> iterable = Arrays.asList(1, 2, null);
 		Assert.assertEquals(3, EntryStream.of(iterable, Function.identity(), Function.identity()).count());
+		Assert.assertEquals(0, EntryStream.of(null, Function.identity(), Function.identity()).count());
 	}
 
 	@Test
@@ -117,11 +134,65 @@ public class EntryStreamTest {
 		Assert.assertEquals(
 			5,
 			EntryStream.of(Arrays.asList(1, 2, 3), Function.identity(), Function.identity())
-				.append(4, 4)
-				.append(5, 5)
+				.push(4, 4)
+				.push(5, 5)
 				.count()
 		);
+	}
 
+	@Test
+	public void testUnshift() {
+		Assert.assertEquals(
+			5,
+			EntryStream.of(Arrays.asList(1, 2, 3), Function.identity(), Function.identity())
+				.unshift(4, 4)
+				.unshift(5, 5)
+				.count()
+		);
+	}
+
+	@Test
+	public void testAppend() {
+		Map<Integer, Integer> map1 = new HashMap<Integer, Integer>(){{
+			put(1, 1);
+			put(2, 2);
+		}};
+		Map<Integer, Integer> map2 = new HashMap<Integer, Integer>(){{
+			put(3, 3);
+			put(4, 4);
+		}};
+		Assert.assertEquals(
+			new ArrayList<Map.Entry<Integer, Integer>>(){{
+				addAll(map1.entrySet());
+				addAll(map2.entrySet());
+			}},
+			EntryStream.of(map1).append(map2.entrySet()).toList()
+		);
+		Assert.assertEquals(
+			new ArrayList<>(map1.entrySet()), EntryStream.of(map1).append(null).toList()
+		);
+	}
+
+	@Test
+	public void testPrepend() {
+		Map<Integer, Integer> map1 = new HashMap<Integer, Integer>(){{
+			put(1, 1);
+			put(2, 2);
+		}};
+		Map<Integer, Integer> map2 = new HashMap<Integer, Integer>(){{
+			put(3, 3);
+			put(4, 4);
+		}};
+		Assert.assertEquals(
+			new ArrayList<Map.Entry<Integer, Integer>>(){{
+				addAll(map2.entrySet());
+				addAll(map1.entrySet());
+			}},
+			EntryStream.of(map1).prepend(map2.entrySet()).toList()
+		);
+		Assert.assertEquals(
+			new ArrayList<>(map1.entrySet()), EntryStream.of(map1).prepend(null).toList()
+		);
 	}
 
 	@Test
@@ -230,6 +301,12 @@ public class EntryStreamTest {
 				.map((k, v) -> k.toString() + v.toString())
 				.collect(Collectors.toList())
 		);
+		Assert.assertEquals(
+			Arrays.asList("11", "22", "33"),
+			EntryStream.of(map)
+				.map(e -> e.getKey().toString() + e.getValue().toString())
+				.collect(Collectors.toList())
+		);
 	}
 
 	@Test
@@ -457,7 +534,7 @@ public class EntryStreamTest {
 		Map<Integer, Integer> map = new HashMap<>();
 		map.put(1, null);
 		map.put(null, 1);
-		Assert.assertEquals(0, EntryStream.of(map).nonNull().count());
+		Assert.assertEquals(0, EntryStream.of(map).nonNullKeyValue().count());
 	}
 
 	@Test
@@ -465,7 +542,7 @@ public class EntryStreamTest {
 		Map<Integer, Integer> map = new HashMap<>();
 		map.put(1, null);
 		map.put(null, 1);
-		Assert.assertEquals(1, EntryStream.of(map).keyNonNull().count());
+		Assert.assertEquals(1, EntryStream.of(map).nonNullKey().count());
 	}
 
 	@Test
@@ -473,7 +550,7 @@ public class EntryStreamTest {
 		Map<Integer, Integer> map = new HashMap<>();
 		map.put(1, null);
 		map.put(null, 1);
-		Assert.assertEquals(1, EntryStream.of(map).valueNonNull().count());
+		Assert.assertEquals(1, EntryStream.of(map).nonNullValue().count());
 	}
 
 	private static class Entry<K, V> implements Map.Entry<K, V> {