鸿蒙开发 之 ArkUI状态管理

1.@state

import { Header } from '../common/components/CommonComponents';

class Person{
  name: string
  age: number
  gf: Person

  constructor(name: string, age: number, gf?: Person) {
    this.name = name
    this.age = age
    this.gf = gf
  }
}

@Entry
@Component
struct StatePage2 {
  idx: number = 1
  @State p: Person = new Person('Jack', 21, new Person('柔丝', 18))
  @State gfs: Person[] = [
    new Person('柔丝', 18),
    new Person('露西', 19),
  ]

  build() {
    Column({space: 10}) {
      Header()

      Text(`${this.p.name} : ${this.p.age}`)
        .fontSize(50)
        .fontWeight(FontWeight.Bold)
        .onClick(() => {
          this.p.age++
        })
      Text(`${this.p.gf.name} : ${this.p.gf.age}`)
        .fontSize(50)
        .fontWeight(FontWeight.Bold)
        .onClick(() => {
          this.p.gf.age++
        })
      Button('添加')
        .onClick(() => {
          this.gfs.push(new Person('女友' + this.idx++, 20))
        })

      Text('=女友列表=')
        .fontSize(50)
        .fontWeight(FontWeight.Bold)
      ForEach(
        this.gfs,
        (p, index) => {
          Row(){
            Text(`${p.name} : ${p.age}`)
              .fontSize(30)
              .onClick(() => {
                this.gfs[index] = new Person(p.name, p.age+1)
              })
            Button('删除')
              .onClick(() => {
                this.gfs.splice(index, 1)
              })
          }
          .width('100%')
          .justifyContent(FlexAlign.SpaceBetween)
        }
      )

    }
    .width('100%')
    .height('100%')
    .padding(10)
  }
}


@Component
struct StatePage {
  @State name: string = 'Jack'
  @State age: number = 21

  build() {
    Column() {
      Text(`${this.name} : ${this.age}`)
        .fontSize(50)
        .fontWeight(FontWeight.Bold)
        .onClick(() => {
          this.age++
        })
    }
    .width('100%')
    .height('100%')
    .justifyContent(FlexAlign.Center)
  }
}

1.2@state任务统计案例

import { Header } from '../common/components/CommonComponents';
// 任务类
@Observed
class Task{
  static id: number = 1
  // 任务名称
  name: string = `任务${Task.id++}`
  // 任务状态：是否完成
  finished: boolean = false
}

// 统一的卡片样式
@Styles function card(){
  .width('95%')
  .padding(20)
  .backgroundColor(Color.White)
  .borderRadius(15)
  .shadow({radius: 6, color: '#1F000000', offsetX: 2, offsetY: 4})
}

// 任务完成样式
@Extend(Text) function finishedTask(){
  .decoration({type:TextDecorationType.LineThrough})
  .fontColor('#B1B2B1')
}

// 任务统计信息
class StatInfo {
  totalTask: number = 0
  finishTask: number = 0
}

@Entry
@Component
struct PropPage {
  // 统计信息
  @Provide stat: StatInfo = new StatInfo()

  build() {
    Column({space: 10}){
      Header()

      // 1.任务进度卡片
      TaskStatistics()

      // 2.任务列表
      TaskList()
    }
    .width('100%')
    .height('100%')
    .backgroundColor('#F1F2F3')
  }
}


@Component
struct TaskStatistics {
  @Consume stat: StatInfo

  build() {
    Row(){
      Text('任务进度：')
        .fontSize(30)
        .fontWeight(FontWeight.Bold)
      Stack(){
        Progress({
          value: this.stat.finishTask,
          total: this.stat.totalTask,
          type: ProgressType.Ring
        })
          .width(100)
        Row(){
          Text(this.stat.finishTask.toString())
            .fontSize(24)
            .fontColor('#36D')
          Text(' / ' + this.stat.totalTask.toString())
            .fontSize(24)
        }
      }
    }
    .card()
    .margin({top: 5, bottom: 10})
    .justifyContent(FlexAlign.SpaceEvenly)
  }
}

@Component
struct TaskList {
  // 总任务数量
  @Consume stat: StatInfo
  // 任务数组
  @State tasks: Task[] = []

  handleTaskChange(){
    // 1.更新任务总数量
    this.stat.totalTask = this.tasks.length
    // 2.更新已完成任务数量
    this.stat.finishTask = this.tasks.filter(item => item.finished).length
  }

  build() {
    Column(){
      // 2.新增任务按钮
      Button('新增任务')
        .width(200)
        .margin({bottom: 10})
        .onClick(() => {
          // 1.新增任务数据
          this.tasks.push(new Task())
          // 2.更新任务总数量
          this.handleTaskChange()
        })

      // 3.任务列表
      List({space: 10}){
        ForEach(
          this.tasks,
          (item: Task, index) => {
            ListItem(){
              TaskItem({item: item, onTaskChange: this.handleTaskChange.bind(this)})
            }
            .swipeAction({end: this.DeleteButton(index)})
          }
        )
      }
      .width('100%')
      .layoutWeight(1)
      .alignListItem(ListItemAlign.Center)
    }
  }

  @Builder DeleteButton(index: number){
    Button(){
      Image($r('app.media.ic_public_delete_filled'))
        .fillColor(Color.White)
        .width(20)
    }
    .width(40)
    .height(40)
    .type(ButtonType.Circle)
    .backgroundColor(Color.Red)
    .margin(5)
    .onClick(() => {
      this.tasks.splice(index, 1)
      this.handleTaskChange()
    })
  }
}

@Component
struct TaskItem {
  @ObjectLink item: Task
  onTaskChange: () => void

  build() {
    Row(){
      if(this.item.finished){
        Text(this.item.name)
          .finishedTask()
      }else{
        Text(this.item.name)
      }
      Checkbox()
        .select(this.item.finished)
        .onChange(val => {
          // 1.更新当前任务状态
          this.item.finished = val
          // 2.更新已完成任务数量
          this.onTaskChange()
        })
    }
    .card()
    .justifyContent(FlexAlign.SpaceBetween)
  }
}

2. @Prop和@Link装饰器

当父子组件之间需要数据同步时，可以使用@Prop和@Link装饰器

2. @Provide和@Consume可以跨组件