List 转字符串后去掉前后 [ ]
第一种
List<String> list = Arrays.asList("a","b","c");
//注意防止空指针
System.out.println(StringUtils.strip(list.toString(),"[]"));
第二种
List<String> list = Arrays.asList("a","b","c");
System.out.println(Joiner.on(",").skipNulls().join(list));