app/lib/utils/color_util.dart

import 'package:flutter/widgets.dart';

class ColorsUtil {
   /// 十六进制颜色，
   /// hex, 十六进制值，例如：0xffffff,
   /// alpha, 透明度 [0.0,1.0]
   static Color hexColor(int hex,{double alpha = 1}){
    if (alpha < 0){
      alpha = 0;
    }else if (alpha > 1){
      alpha = 1;
    }
    return Color.fromRGBO((hex & 0xFF0000) >> 16 ,
         (hex & 0x00FF00) >> 8,
         (hex & 0x0000FF) >> 0,
         alpha);
   }
   static Color hexToColor(String s) {
    // 如果传入的十六进制颜色值不符合要求，返回默认值
    if (s == null || s.length != 7 ||
        int.tryParse(s.substring(1, 7), radix: 16) == null) {
      s = '#999999';
    }
    return new Color(int.parse(s.substring(1, 7), radix: 16) + 0xFF000000);
  }
}