鸿蒙实战开发：数据交互【RPC连接】

概述

本示例展示了同一设备中前后台的数据交互，用户前台选择相应的商品与数目，后台计算出结果，回传给前台展示。

样例展示

基础信息

RPC连接

介绍

本示例使用[@ohos.rpc]相关接口，实现了一个前台选择商品和数目，后台计算总价的功能，使用rpc进行前台和后台的通信。

效果预览

主页	选择列表

使用说明：

点击商品种类的空白方框，弹出商品选择列表，选择点击对应的商品，空白方框显示相应内容。
点击商品选择框后的 + 或 - 按钮，选择商品所对应的数量。
点击 Confirm an order 按钮，根据相应的菜品数量与单价，计算出总价并显示。

具体实现

发送数据：在首页的sortString()中通过rpc.MessageSequence.create()创建MessageSequence对象，然后通过MessageSequence.writeStringArray()将我们的处理过的购物数据写入MessageSequence对象中，通过rpc.RemoteObject.sendMessageRequest()将我们得出总价所需要的参数发送到进程中，源码参考：[Index.ets]

Copyright (c) 2021-2023 Huawei Device Co., Ltd.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

import rpc from '@ohos.rpc'

import ReceivedData from '../model/ReceivedData'

import { ProcessData } from '../model/ProcessData'

import { Logger } from '../common/Logger'

import { MyDataSource } from '../model/OptionsData'

import { OPTIONS } from '../muck/MyData'

import { TitleBar } from '../common/TitleBar'

import { FlexList } from '../common/FlexList'

const REQUEST_CODE: number = 1

type SelectType = {

subcategory: string,

count: number

}

@Entry

@Component

struct Index {

@State send: string = ''

@State result: number = 0

private Process: ProcessData = new ProcessData()

private selectStuffs: Array<SelectType> = new Array(4).fill({ subcategory: '', count: 0 })



selectStuff(index: number, good: string, count: number) {

  Logger.info(`index=  ${index}, count= ${count}, good= ${good}`)

  this.selectStuffs[index] = { subcategory: good, count: count }

}



async sortString(sendData: Array<string>) {

  Logger.info(`sortString is ${sendData}`)

  Logger.info(`sendData typeof ${typeof (sendData)}`)

  let option: rpc.MessageOption = new rpc.MessageOption()

  let data: rpc.MessageSequence = rpc.MessageSequence.create()

  let reply: rpc.MessageSequence = rpc.MessageSequence.create()

  Logger.info(`getCallingUid: ${ReceivedData.getCallingUid()}  getCallingPid: ${ReceivedData.getCallingPid()}`)

  data.writeStringArray(sendData)

  try {

    await ReceivedData.sendMessageRequest(REQUEST_CODE, data, reply, option)

  } catch (err) {

    Logger.error(`sortString failed, ${JSON.stringify(err)}`)

  }

  this.result = reply.readInt()

  reply.reclaim()

}



build() {

  Scroll() {

    Column() {

      TitleBar()

      LazyForEach(new MyDataSource(OPTIONS), (item, index) => {

        Row() {

          FlexList({

            category: item.category,

            menu: item.subcategory,

            index: index,

            selectStuff: this.selectStuff.bind(this)

          })

        }

      }, item => JSON.stringify(item))



      Column() {

        Row() {

          Text($r('app.string.final_price'))

            .width('65%')

            .height(25)

            .fontSize(18)

            .textAlign(TextAlign.Center)



          Text(this.result.toString())

            .id('totalPrice')

            .height(25)

            .fontSize(20)

            .margin({ left: '5%' })

            .textAlign(TextAlign.Center)

        }

        .justifyContent(FlexAlign.Center)

        .width('80%')



        Button($r('app.string.confirm'))

          .id('confirmOrderBtn')

          .width('80%')

          .height(40)

          .margin({ top: 30 })

          .onClick(() => {

            let priceArray = this.Process.getPrice(this.selectStuffs)

            Logger.info(`priceArray= ${priceArray}`)

            this.sortString(priceArray)

          })

      }

      .width('100%')

      .justifyContent(FlexAlign.Center)

      .margin({ top: 20 })

      .height('30%')

    }

    .width('100%')

  }

}

}

读取数据：处理MessageRequest请求的接口封装在ReceivedData里面，在这里接收传递来的数据，然后经过处理得出总价，并通过rpc.MessageParcel.writeInt()写入MessageParcel对象，源码参考：[ReceivedData.ets]

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

import rpc from '@ohos.rpc'

import { Logger } from '../common/Logger'

import { PRICE_LIST } from '../muck/MyData'

const TAG = '[eTSRPC.ReceivedData]'

let resultList: Array<number> = Array.from({ length: 4 }, () => 0)

class ReceivedData extends rpc.RemoteObject {

onRemoteRequest(code: number, data: rpc.MessageParcel, reply: rpc.MessageParcel, option: rpc.MessageOption): boolean {

  Logger.info(TAG, `called`)

  if (code === 1) {

    let result = 0

    let readIntArr

    try {

      readIntArr = data.readStringArray()

    } catch (err) {

      Logger.error(`readStringArray failed, code is ${err.code}, message is ${err.message}`)

    }

    Logger.info(TAG, `readIntArr= ${readIntArr}`)

    for (let i = 0; i < 4; i++) {

      if (readIntArr[i] === '0') {

        resultList[i] = 0

      } else {

        resultList[i] = PRICE_LIST.get(readIntArr[i]) * Number(readIntArr[i+4])

      }

      Logger.info(TAG, `this.resultList= ${resultList}`)

      result += resultList[i]

    }

    try {

      reply.writeInt(result)

    } catch (err) {

      Logger.error(TAG, `writeInt failed, code is ${err.code}, message is ${err.message}`)

    }

    Logger.info(TAG, `result= ${result}`)

  } else {

    Logger.info(TAG, `unknown request code`)

  }

  return true

}

}

export default new ReceivedData('send')

鸿蒙OpenHarmony知识待更新