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

使用说明：

1. 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。
2. 点击商品选择框后的 + 或 - 按钮，选择商品所对应的数量。
3. 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 = 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) {

    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%')

    }

  }

}
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• 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]

/*

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

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



const TAG = '[eTSRPC.ReceivedData]'

let resultList: Array = 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')
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