废话不多说，代码走起，

//判断是否微信登陆
isWeiXinLogin() {
    var ua = window.navigator.userAgent.toLowerCase();
    console.log(ua);//mozilla/5.0 (iphone; cpu iphone os 9_1 like mac os x) applewebkit/601.1.46 (khtml, like gecko)version/9.0 mobile/13b143 safari/601.1
    if (ua.match(/MicroMessenger/i) == 'micromessenger') {
        return true; // 微信中打开
    } else {
        return false; // 普通浏览器中打开
    }
},

实例： app 分享下载页面的链接到微信中，用户点击链接在微信中打开，点击下载确不是跳转到浏览器中进行下载，而是直接在微信中打开下载文件，会出现乱码，所有需要 判断是否是在微信浏览器中打开还是在普通浏览器中打开，

image.png

上代码：

<template>
    <view>
        <view class="top-img"><image src="../../static/img/download-img.png" mode=""></image></view>
        <view class="content-box100"></view>
        <view class="download-wrap">
            <view class="left-logo">
                <image src="../../static/img/logo.png" mode=""></image>
                <text class="js-text">应用名称</text>
            </view>
            <button class="download-btn" @click="DownLoadAndroid">安卓下载</button>
        </view>
        <view class="content-box50"></view>
        <view class="download-wrap">
            <view class="left-logo">
                <image src="../../static/img/logo.png" mode=""></image>
                <text class="js-text">应用名称</text>
            </view>
            <button class="download-btn" @click="DownLoadIOS">IOS下载</button>
        </view>
        <view class="content-box100"></view>
        <view class="content-box50"></view>
        <!-- 弹出层插件 -->
        <uni-popup ref="popup" type="dialog">
            <uni-popup-dialog type="input" mode="base" :content="content" :duration="2000" :before-close="true" @close="close" @confirm="confirm">IOS下载暂未开放</uni-popup-dialog>
        </uni-popup>
    </view>
</template>

export default {
    data() {
        return {
            content: '',
            platform: ''
        };
    },
    onLoad() {
        uni.getSystemInfo({
            success: res => {
                console.log(res.platform)
                this.$data.platform = res.platform;
            }
        });
          
    },
    methods: {
        //判断是否微信登陆
        isWeiXinLogin() {
            var ua = window.navigator.userAgent.toLowerCase();
            console.log(ua);//mozilla/5.0 (iphone; cpu iphone os 9_1 like mac os x) applewebkit/601.1.46 (khtml, like gecko)version/9.0 mobile/13b143 safari/601.1
            if (ua.match(/MicroMessenger/i) == 'micromessenger') {
                return true;
            } else {
                return false;
            }
        },
        //安卓下载
        DownLoadAndroid() {
            if (this.isWeiXinLogin()) {
                uni.showToast({
                    icon:'none',
                    title:'点击右上角 ··· 在浏览器中打开下载',
                    duration:3000
                })
                return;
            }
            var downloadUrl = 'http://192.168.0.251:9999/android/android.apk'; // 下载地址
            var urlStr = encodeURI(downloadUrl)
            // #ifdef APP-PLUS
            plus.runtime.openURL(urlStr);
            return;
            // #endif
            
            // #ifdef H5 
            window.open(urlStr);
            // #endif
        },
        // IOS下载
        DownLoadIOS() {
            uni.showToast({
                icon: 'none',
                title: 'IOS下载暂未开放',
                duration: 3000
            });
        },
    }
};
</script>

CSS

<style lang="less">
.top-img {
    width: 750rpx;
    height: 685rpx;
    image {
        width: 750rpx;
        height: 685rpx;
    }
}
.download-wrap {
    display: flex;
    width: 670rpx;
    margin: 0 auto;
    justify-content: space-between;
    align-items: center;
    .left-logo {
        height: 160rpx;
        display: flex;
        align-items: center;
        .js-text {
            font-size: 40rpx;
            font-weight: 500;
            color: #000000;
            margin-left: 10rpx;
        }
        image {
            width: 160rpx;
            height: 160rpx;
        }
    }
    .download-btn {
        width: 250rpx;
        height: 80rpx;
        background: linear-gradient(359deg, rgba(47, 128, 237, 1) 0%, rgba(86, 204, 242, 1) 100%);
        text-align: center;
        line-height: 80rpx;
        border-radius: 40px;
        box-shadow: 0px 1px 4px 0px rgba(47, 128, 237, 0.6);
        color: #ffffff;
        font-size: 40rpx;
        margin: 0;
        font-weight: 500;
    }
}
</style>