String[] strArray = {"aaa","bbb","ccc"}；
String str= StringUtils.join(strArry,",");
System.out.println(str);

String str = "aaa,bbb,ccc";
String strArray = str.split(",");
for(String s : strArray){
  System.out.println(s);   
}

//数据源
String string = "1,2,3,4,5";
//长度5 下标从0开始 到4
String substring = string.substring(0, string.length() - 1);
//以逗号分割，得出的数据存到 result 里面
String[] result = substring.split(",");
for (String r : result) {
  System.out.println("分割结果是: " + r);
}