uniapp实现app自动更新详细步骤

onShow: function() {
	console.log('App Show')
	plus.runtime.getProperty(plus.runtime.appid, function(widgetInfo) {
	this.version = widgetInfo.version
	uni.request({
		url: 'http://xxxx.cczu.edu.cn:8081/api/dict',
		success: (res) => {
			function compareVersion(version1, version2) {
				const newVersion1 = `${version1}`.split('.').length < 3 ? `${version1}`.concat('.0') : `${version1}`;
				const newVersion2 = `${version2}`.split('.').length < 3 ? `${version2}`.concat('.0') : `${version2}`;
				  //计算版本号大小,转化大小
				 function toNum(a){
				 	const c = a.toString().split('.');
				 	const num_place = ["", "0", "00", "000", "0000"],
				 		r = num_place.reverse();
				 	for (let i = 0; i < c.length; i++){
				 		const len=c[i].length;
				 		c[i]=r[len]+c[i];
				 	}
				 		return c.join('');
				 	}
				 	// 检测版本号是否需要更新
				 	function checkPlugin(a, b) {
				 		const numA = toNum(a);
				 		const numB = toNum(b);
				 		return numA > numB ? 1 : numA < numB ? -1 : 0;
				 	}
				 		return checkPlugin(newVersion1 ,newVersion2);
				 	}
				 	for (let i of res.data.content) {
				 		if (i.description === 'app版本') {
							// 1代表app新包版本号大于本地版本号
				 			if (compareVersion(i.dictDetails[0].value, this.version) === 1) {
				 				uni.showModal({
				 					title: '提示',
				 					content: '发现新的应用安装包，点击确定立即更新',
				 					success: function (res) {
				 					   if (res.confirm) {
				 					       	console.log('用户点击确定');
											uni.showLoading({
												title: '更新中……'
											})
				 							uni.downloadFile({
				 								// 存放最新安装包的地址
				 								url: 'http://xxxx.xxxx.com/__UNI__xxxx.apk',
				 								success: (downloadResult) => {  
													uni.hideLoading();
				 								    if (downloadResult.statusCode === 200) { 
														uni.hideLoading();
				 								        plus.runtime.install(downloadResult.tempFilePath,{ 
				 								        	force: false 
				 								        }, function() {
				 								        	console.log('install success...');  
				 								            plus.runtime.restart();  
				 								        }, function(e) {  
															uni.hideLoading();
				 								            console.error('install fail...');  
				 								        });  
				 								    }
				 								}  
				 							}); 
				 					   } else if (res.cancel) {
				 					   		console.log('用户点击取消');
				 					   }
				 					}
				 				});
				 			} else {
				 		}
				 	}
				 }
			}
		});
	});
},