webview打开本地Html文件
1.在路径前面加上file://
String filePath="file://"+path;webView.loadUrl( filePath);
2.打开权限
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
3.启用JavaScript 设置本地访问权限
webView.getSettings().setJavaScriptEnabled(true);webSettings.setAllowContentAccess(true);
4.如果js代码访问本地文件出现CORS跨源请求 可以通过重写WebViewClient的shouldInterceptRequest函数拦截请求并替换为本地资源
webView.setWebViewClient(new WebViewClient(){@Nullable@Overridepublic WebResourceResponse shouldInterceptRequest(WebView view, WebResourceRequest request) {// 获取请求的URLString url = null;if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {url = request.getUrl().toString();}// 检查URL是否符合你想要替换的file域规则if (url.startsWith("file://")) {String path=url;try {if(path.contains(".jpg")||path.contains(".png")){Map<String, String> headers = new HashMap<>();headers.put("Access-Control-Allow-Origin", "*");InputStream inputStream = new FileInputStream(new File(path));if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {WebResourceResponse response= new WebResourceResponse("image/png", "UTF-8", inputStream);if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {response.setResponseHeaders(headers);}return response;}}else {} catch (IOException e) {// 处理异常e.printStackTrace();}}// 如果不是file域请求，则返回null继续加载return super.shouldInterceptRequest(view, request);}});
5.如果H5项目中用到了Fetch 出现报错Fetch API cannot load 是因为Fetch不支持使用file://访问本地文件， 可以在html文件中处理下
如果是 arraybuffer 可以这样处理
<script>window.fetch=function fetchLocal(url, data) {return new Promise(function (resolve, reject) {var xhr = new XMLHttpRequestxhr.onload = function () {resolve(new Response(xhr.response, { status: xhr.status }))}xhr.onerror = function () {reject(new TypeError('Local request failed'))}xhr.open('GET', url)xhr.responseType = "arraybuffer";xhr.send(null)})
}</script>
否则可以这样处理下
<script>window.fetch=function fetchLocal(url, data) {return new Promise(function(resolve, reject) {var xhr = new XMLHttpRequestxhr.onload = function() {resolve(new Response(xhr.responseText, {status: xhr.status}))}xhr.onerror = function() {reject(new TypeError('Local request failed'))}xhr.open('GET', url)xhr.send(data)})
}</script>
至此，就可以离线访问本地的Unity，Cocos等H5游戏