Flutter 修改 DropdownButton 按钮的背景色

Flutter 修改 DropdownButton 按钮的背景色

 Container(
            padding: const EdgeInsets.symmetric(horizontal: 20.0),
            child: Row(
              mainAxisAlignment: MainAxisAlignment.spaceBetween,
              children: [
                Text(widget.title),
                Container(
                  height: 30.0,
                  padding:
                      const EdgeInsets.symmetric(horizontal: 10, vertical: 5),
                  decoration: BoxDecoration(
                    color: const Color(0xFFF7F9FA),
                    borderRadius: BorderRadius.circular(8),
                  ),
                  child: DropdownButton<String>(
                    value: dropdownValue,
                    elevation: 16,
                    underline: Container(
                      height: 2,
                    ),
                    onChanged: (String? newValue) {
                      setState(() {
                        dropdownValue = newValue!;
                      });
                    },
                    items: <String>['年', '月', '日']
                        .map<DropdownMenuItem<String>>((String value) {
                      return DropdownMenuItem<String>(
                        value: value,
                        child: Text(value),
                      );
                    }).toList(),
                  ),
                )
              ],
            ),
          ),