应用子窗口的开发流程是什么

import UIAbility from '@ohos.app.ability.UIAbility'; 
import window from '@ohos.window'; 
import { BusinessError } from '@ohos.base'; 
 
let windowStage_: window.WindowStage | null = null; 
let sub_windowClass: window.Window | null = null; 
 
export default class EntryAbility extends UIAbility { 
  showSubWindow() { 
    // 1.创建应用子窗口。 
    if (windowStage_ == null) { 
      console.error('Failed to create the subwindow. Cause: windowStage_ is null'); 
    } else { 
      windowStage_.createSubWindow("mySubWindow", (err: BusinessError, data) => { 
        if (err.code) { 
          console.error('Failed to create the subwindow. Cause: ' + JSON.stringify(err)); 
          return; 
        } 
        sub_windowClass = data; 
        // 2.子窗口创建成功后，设置子窗口的位置、大小及相关属性等。 
        sub_windowClass.moveWindowTo(300, 300, (err: BusinessError) => { 
          if (err.code) { 
            console.error('Failed to move the window. Cause:' + JSON.stringify(err)); 
            return; 
          } 
          console.info('Succeeded in moving the window.'); 
        }); 
        sub_windowClass.resize(500, 500, (err: BusinessError) => { 
          if (err.code) { 
            console.error('Failed to change the window size. Cause:' + JSON.stringify(err)); 
            return; 
          } 
          console.info('Succeeded in changing the window size.'); 
        }); 
        // 3.为子窗口加载对应的目标页面。 
        sub_windowClass.setUIContent("pages/page3", (err: BusinessError) => { 
          if (err.code) { 
            console.error('Failed to load the content. Cause:' + JSON.stringify(err)); 
            return; 
          } 
          // 3.显示子窗口。 
          (sub_windowClass as window.Window).showWindow((err: BusinessError) => { 
            if (err.code) { 
              console.error('Failed to show the window. Cause: ' + JSON.stringify(err)); 
              return; 
            } 
            console.info('Succeeded in showing the window.'); 
          }); 
        }); 
      }) 
    } 
  } 
  destroySubWindow() { 
    // 4.销毁子窗口。当不再需要子窗口时，可根据具体实现逻辑，使用destroy对其进行销毁。 
    (sub_windowClass as window.Window).destroyWindow((err: BusinessError) => { 
      if (err.code) { 
        console.error('Failed to destroy the window. Cause: ' + JSON.stringify(err)); 
        return; 
      } 
    }); 
  } 
  onWindowStageCreate(windowStage: window.WindowStage) { 
    windowStage_ = windowStage; 
    // 开发者可以在适当的时机，如主窗口上按钮点击事件等，创建子窗口。并不一定需要在onWindowStageCreate调用，这里仅作展示 
    this.showSubWindow(); 
  } 
  onWindowStageDestroy() { 
    // 开发者可以在适当的时机，如子窗口上点击关闭按钮等，销毁子窗口。并不一定需要在onWindowStageDestroy调用，这里仅作展示 
    this.destroySubWindow(); 
  } 
};