整形数组List<int>转为字符串

  List<int> charCodes = const [97, 98, 99, 100];
  print(String.fromCharCodes(charCodes));  //"abcd"

字符串转整形数组List<int>

List<int> a = "ABCD".codeUnits;
print(a);  // [65, 66, 67, 68]

字符 <------->ASCII值
A <-------->65
B <-------->66
C <-------->67
D <-------->68