h5与原生的交互，JSBridge

1.新建一个文件

// import Vue from 'vue';
export const setupWebViewJavascriptBridge = callback => {
    var u = navigator.userAgent;
    var isiOS = !!u.match(/\(i[^;]+;( U;)? CPU.+Mac OS X/);
    if (!isiOS) {
        if (window.WebViewJavascriptBridge) {
            // eslint-disable-next-line no-undef
            callback(WebViewJavascriptBridge);
        } else {
            document.addEventListener(
                'WebViewJavascriptBridgeReady',
                function () {
                    // eslint-disable-next-line no-undef
                    callback(WebViewJavascriptBridge);
                },
                false
            );
        }
    } else {
        if (window.WebViewJavascriptBridge) {
            return callback(window.WebViewJavascriptBridge);
        }
        if (window.WVJBCallbacks) {
            return window.WVJBCallbacks.push(callback);
        }
        window.WVJBCallbacks = [callback];
        var WVJBIframe = document.createElement('iframe');
        WVJBIframe.style.display = 'none';
        WVJBIframe.src = 'wvjbscheme://__BRIDGE_LOADED__';
        document.documentElement.appendChild(WVJBIframe);
        setTimeout(function () {
            document.documentElement.removeChild(WVJBIframe);
        }, 0);
    }
};

export const  appUtil={
    //网点管家下载附件
    downLoadFn(params){
        setupWebViewJavascriptBridge(function(bridge){
            bridge.callHandler('downLoadFn',params)
        })
    }
}

2.在那个页面中使用，就在那个页面中引入，并且调用改方法

import { appUtil } from "../assets/JSBridge/JSBridge.js";
appUtil.downLoadFn(params)//调用原生方法

或者下载的时候拿到url的地址http：//xxx,让安卓监听一下Webview监听下载的回调，然后让手机浏览器下载就行
安卓的代码

webView.setDownloadListener(new DownloadListener() {
            @Override
            public void onDownloadStart(String url, String userAgent, String contentDisposition, String mimetype, long contentLength) {
                Intent intent = new Intent(Intent.ACTION_VIEW);
                intent.addCategory(Intent.CATEGORY_BROWSABLE);
                intent.setData(Uri.parse(url));
                startActivity(intent);
            }
        });