TextArea有特殊字符时，将下划线变红并且添加提示，删除特殊字符以后再恢复如何实现？

@Entry 
@Component 
struct Second { 
  @State message: string = 'Hello World'; 
  @State isFlag: boolean = false; 
  private text: string = ''; 
 
  isHasSpecialCharacter(value: string) { 
    let addStr = value.substring(this.text.length) 
    let regex = new RegExp(/[`~!@#$%^&*()_\-+=<>?:"{}|,.\/;'\\[\]·~！@#￥%……&*（）——\-+={}|《》？：“”【】、；‘'，。、]/); 
    if (!regex.test(addStr)) { 
      this.text = value 
      this.isFlag = false 
    } else { 
      this.isFlag = true 
    } 
  } 
 
  build() { 
    Row() { 
      Column() { 
        Text(this.message) 
          .fontSize(30) 
          .fontWeight(FontWeight.Bold) 
          .margin({ top: 20 }) 
        TextArea({ text: this.text, placeholder: "请输入" }) 
          .width("80%") 
          .height("25%") 
          .margin({ left: 10, top: 10 }) 
          .onChange((value) => { 
            this.isHasSpecialCharacter(value); 
          }) 
        if (this.isFlag) { 
          Divider() 
            .vertical(false) 
            .color(Color.Red) 
            .strokeWidth(2) 
            .width("80%") 
            .margin({ left: 10, top: 10 }) 
          Text('不能包含特殊字符') 
            .fontSize(20) 
            .fontColor(Color.Red) 
            .margin({ left: 10, top: 10 }) 
            .textAlign(TextAlign.Start) 
            .width("80%") 
        } 
      } 
      .height('100%') 
      .width('100%') 
    } 
  } 
}