1.fix sql issue

luoo_music/src/main/java/com/luoo/music/service/TagService.java

@@ -1,5 +1,6 @@
 package com.luoo.music.service;
 
+import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 import java.util.stream.Collectors;
@@ -28,6 +29,9 @@ public class TagService {
 	}
 
 	public Map<String, List<String>> getTagMap(List<String> journalIds) {
+		if(journalIds.isEmpty()) {
+			return Collections.emptyMap();
+		}
 		List<Object[]> pairs = tagDao.getJounralId2TagPairs(journalIds);
 		return pairs.stream().collect(Collectors.groupingBy(s -> s[0].toString(),
 				Collectors.mapping(s -> s[1].toString(), Collectors.toList())));