HarmonyOS 怎么控制web返回上一页？

@Entry  
@Component  
struct WebComponent {  
  controller: WebController = new WebController()  
  
  build() {  
    Column() {  
      Button('backward')  
        .onClick(() => {  
          this.controller.backward()  
        })  
      Web({ src: 'www.example.com', controller: this.controller })  
    }  
  }  
}