fix io bug

hutool-core/src/test/java/cn/hutool/core/io/CharsetDetectorTest.java

@@ -0,0 +1,19 @@
+package cn.hutool.core.io;
+
+import cn.hutool.core.io.resource.ResourceUtil;
+import cn.hutool.core.util.CharsetUtil;
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.nio.charset.Charset;
+
+public class CharsetDetectorTest {
+
+	@Test
+	public void detectTest(){
+		// 测试多个Charset对同一个流的处理是否有问题
+		final Charset detect = CharsetDetector.detect(ResourceUtil.getStream("test.xml"),
+				CharsetUtil.CHARSET_GBK, CharsetUtil.CHARSET_UTF_8);
+		Assert.assertEquals(CharsetUtil.CHARSET_UTF_8, detect);
+	}
+}