检查的方法是放在app.vue里面的

	<script>
	import { hostCharge } from "util/httpUrl.js"
	import Util from "util/util.js"
		
	export default {
		onLaunch: function() {
			
			// console.log('App Launch')
			//#ifdef APP-PLUS
			this.checkUpdateVersion()
			
			//#endif
			
		},
		methods: {
			//检查版本更新
			async checkUpdateVersion(){
				//锁定屏幕方向
				plus.screen.lockOrientation('portrait-primary')
				try{
					//获取版本更新
					let { data: { data, code, flag, message } } = await Util.httpRequest({
						url: `${hostCharge}/check/version`,
						data: {
							versionCode: uni.getStorageSync('versionCode')
						}
					})
					if(code === 20000){
						uni.showModal({
							title: '温馨提示',
							content: `有新的版本可下载${data.versionCode}是否下载？`,
							success:(res) => {
								if(res.confirm){
									console.log(res.confirm)
									//判断手机类型
									// 也可以用5+app的方法:plus.os.name.toLowerCase() == 'ios'
									if(uni.getSystemInfoSync().platform === 'ios'){
										plus.runtime.openURL(data.updateUrl)
									} else {
										//新建下载任务
										var downloadTask = plus.downloader.createDownload(data.updateUrl, {}, (download,status) => {
											if(status === 200){
												//安装APK文件
												plus.runtime.install(download.filename, {}, function(error) {
													uni.showModal({
														showCancle: false,
														content: '安装失败'
													})
												})
											} else {
												uni.showModal({
													showCancle: false,
													title: '更新失败！！！'
												})
											}
										})
										try {
											// 开始下载
											downloadTask.start()
											//监听下载
											var that = this 
											var showLoading = plus.nativeUI.showWaiting("正在下载")
											downloadTask.addEventListener('statechanged', function(download,status){
												switch (download.state) {
													case 1:
														uni.showToast({
															title: '下载中'
														})
														break;
													case 2:
														//出现下载弹框和进度
														that.$scope.globalData.updateProgress.popup = true
														that.$scope.globalData.updateProgress.percent = parseInt(parseFloat(download.downloadedSize) / parseFloat(download.totalSize) * 100)
																	
														// uni.showLoading({
														// 	title: `正在下载${that.$scope.globalData.updateProgress.percent}%`
														// })
														break;
													case 3:
														plus.nativeUI.closeWaiting()
												}
											})
										} catch (err) {
											plus.nativeUI.closeWaiting()
											uni.showModal({
												showCancle: false,
												content: '下载失败，请稍后重试'
											})
										}
									}
									//检验过一次版本就加入缓存，不再检测
									uni.setStorageSync('isCheckVersion', true)
								}
							}
						})
					} else {
						uni.showModal({
							showCancle: false,
							content: message
						})
					}
				} catch(e) {
					uni.showModal({
						showCancle: false,
						content: '获取数据失败'
					})
				}
			}
		},
		globalData: {
			userInfo: {},
			restaurantData: {},
			//下载弹窗和进度条
			updateProgress: {
				popup: false,
				precent: 0
			}
		}
	}
</script>

在首页的onReady生命周期进行判断updateProgress的popup，为true的显示弹框，对precent进行赋值
弹框我就没展示了，虽然页面有点丑，哈哈哈