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：

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 = 1type SelectType = {subcategory: string,count: number}@Entry@Componentstruct Index {@State send: string = ''@State result: number = 0private 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]

/** 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<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 = 0let readIntArrtry {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