update

examcloud-commons/src/main/java/cn/com/qmth/examcloud/commons/util/FileUtil.java

@@ -1,5 +1,7 @@
 package cn.com.qmth.examcloud.commons.util;
 
+import org.apache.commons.lang3.StringUtils;
+
 import java.io.File;
 import java.util.Arrays;
 import java.util.Comparator;
@@ -13,24 +15,40 @@ import java.util.Comparator;
  */
 public class FileUtil {
 
-	/**
-	 * 排序
-	 *
-	 * @author WANGWEI
-	 * @param files
-	 */
-	public static void sortByLastUpdateTime(File... files) {
-		Arrays.sort(files, new Comparator<File>() {
-			public int compare(File f1, File f2) {
-				long diff = f1.lastModified() - f2.lastModified();
-				if (diff > 0)
-					return 1;
-				else if (diff == 0)
-					return 0;
-				else
-					return -1;
-			}
-		});
-	}
+    /**
+     * 排序
+     *
+     * @param files
+     * @author WANGWEI
+     */
+    public static void sortByLastUpdateTime(File... files) {
+        Arrays.sort(files, new Comparator<File>() {
+            public int compare(File f1, File f2) {
+                long diff = f1.lastModified() - f2.lastModified();
+                if (diff > 0)
+                    return 1;
+                else if (diff == 0)
+                    return 0;
+                else
+                    return -1;
+            }
+        });
+    }
+
+    /**
+     * 获取文件后缀名，包括"."
+     */
+    public static String getFileSuffix(String fileName) {
+        if (StringUtils.isEmpty(fileName)) {
+            return "";
+        }
+
+        int index = fileName.lastIndexOf(".");
+        if (index > 0) {
+            return fileName.substring(index).toLowerCase();
+        }
+
+        return "";
+    }
 
 }