add Stream utils

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

@@ -0,0 +1,16 @@
+package cn.hutool.core.stream;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.util.stream.Stream;
+
+public class StreamUtilTest {
+
+	@Test
+	public void ofTest(){
+		final Stream<Integer> stream = StreamUtil.of(2, x -> x * 2, 4);
+		final String result = stream.collect(CollectorUtil.joining(","));
+		Assert.assertEquals("2,4,8,16", result);
+	}
+}