Shulou(Shulou.com)06/02 Report--

Editor to share with you a sample analysis of the basic application of Android WebView, I hope you will gain something after reading this article, let's discuss it together!

First, the basic configuration of WebView WebSettings ws = getSettings (); ws.setBuiltInZoomControls (true); / / hide the zoom button ws.setLayoutAlgorithm (WebSettings.LayoutAlgorithm.NORMAL); / / typesetting to adapt to the screen ws.setUseWideViewPort (true); / / scalable ws.setLoadWithOverviewMode (true); / / setUseWideViewPort method to set the window recommended by webview. The setLoadWithOverviewMode method sets the mode of the page loaded by webview. Ws.setSaveFormData (true); / / Save form data ws.setJavaScriptEnabled (true); / / whether you can interact with JS [if there is no JS interaction in the business, it is recommended to turn this off] ws.setGeolocationEnabled (true); / / enable geolocation [if there is no such service in the business, it is recommended to turn this off] ws.setDomStorageEnabled (true); ws.setJavaScriptCanOpenWindowsAutomatically (true) / allow the JS Alert dialog box to open [if there is no such business in the business, it is recommended to disable] ws.setSupportMultipleWindows (true); / / add 2, WebView supports music playback / / whether music playback ws.setPluginState (WebSettings.PluginState.ON); ws.setMixedContentMode (WebSettings.MIXED_CONTENT_ALWAYS_ALLOW); / / whether users are required to click to play ws.setMediaPlaybackRequiresUserGesture (true); 3. WebView supports video playback.

Android WebView plays videos (including full screen playback)

4. WebChromeClient/** * WebChromeClient is a dialog box that assists WebView in dealing with Javascript, website icon, website title, loading progress, etc. * / setWebChromeClient (new XWebChromeClient ())

The specific coverage methods are as follows:

Public static class XWebChromeClient extends WebChromeClient {/ * get page loading progress * @ param view * @ param newProgress * / @ Override public void onProgressChanged (WebView view, int newProgress) {super.onProgressChanged (view, newProgress); Log.d (TAG, "onProgressChanged--- > newProgress:" + newProgress) } / * get the website title (Android 6.0and get [capture HTTP ERROR] via title) * * @ param view * @ param title * / @ Override public void onReceivedTitle (WebView view, String title) {super.onReceivedTitle (view, title) Log.d (TAG, "onReceivedTitle--- > title:" + title); if (webTitleCallBack! = null) {webTitleCallBack.onReceived (title);} if (Build.VERSION.SDK_INT)

< Build.VERSION_CODES.M) { if (title.contains("404") || title.contains("500") || title.contains("Error")) { view.loadUrl("about:blank"); // 避免出现默认的错误界面 // 在这里可以考虑显示自定义错误页 // showErrorPage(); } } } /** * 网站图标 * * @param view * @param icon */ @Override public void onReceivedIcon(WebView view, Bitmap icon) { super.onReceivedIcon(view, icon); Log.d(TAG, "icon:" + icon); } /** * 拦截Alert弹框 * * @param view * @param url * @param message * @param result * @return */ @Override public boolean onJsAlert(WebView view, String url, String message, JsResult result) { Log.d(TAG, "onJsAlert"); return super.onJsAlert(view, url, message, result); } /** * 拦截 confirm弹框 * * @param view * @param url * @param message * @param result * @return */ @Override public boolean onJsConfirm(WebView view, String url, String message, JsResult result) { Log.d(TAG, "onJsConfirm"); return super.onJsConfirm(view, url, message, result); } /** * 打印console信息 * * @param consoleMessage * @return */ @Override public boolean onConsoleMessage(ConsoleMessage consoleMessage) { Log.d(TAG, "onConsoleMessage"); return super.onConsoleMessage(consoleMessage); } /** * 该方法在web页面请求某个尚未被允许或拒绝的权限时回调 * * @param request */ @Override public void onPermissionRequest(PermissionRequest request) { super.onPermissionRequest(request); Log.d(TAG, "onPermissionRequest--->

Request: "+ request);}} V. WebViewClient/** * WebViewClient is the * / setWebViewClient (new XWebViewClient ()) that helps WebView handle various notifications and request events.

The specific coverage methods are as follows:

Public class XWebViewClient extends WebViewClient {@ Override public void onPageStarted (WebView view, String url, Bitmap favicon) {super.onPageStarted (view, url, favicon); Log.d (TAG, "onPageStarted--- > url:" + url);} @ Override public void onPageFinished (WebView view, String url) {super.onPageFinished (view, url) Log.d (TAG, "onPageFinished--- > url:" + url); callback when loading errors on the WEB page, which are usually caused by a failure to connect to the server properly. * * @ param view * @ param errorCode * @ param description * @ param failingUrl * / the previous method [may also be called in the new version, so add a judgment Prevent repetition of] @ Override public void onReceivedError (WebView view, int errorCode, String description, String failingUrl) {super.onReceivedError (view, errorCode, description, failingUrl) If (Build.VERSION.SDK_INT

< Build.VERSION_CODES.M) { // 断网或者网络连接超时 showReceivedErrorPage(view, errorCode, description, failingUrl); } } /** * 当服务器返回错误码时回调 * * @param view * @param request * @param errorResponse */ //6.0新增方法 @RequiresApi(api = Build.VERSION_CODES.M) @Override public void onReceivedHttpError(WebView view, WebResourceRequest request, WebResourceResponse errorResponse) { super.onReceivedHttpError(view, request, errorResponse); // 这个方法在6.0才出现 if (Build.VERSION.SDK_INT >

= Build.VERSION_CODES.M) {int statusCode = 0; if (errorResponse! = null) {statusCode = errorResponse.getStatusCode ();} Log.d (TAG, "onReceivedHttpError--- > code =" + statusCode) If (404 = = statusCode | | 500 = = statusCode) {view.loadUrl ("about:blank"); / / avoid default error interface / / here you can consider displaying a custom error page / / showErrorPage ();}}

There are also the following methods, which should be paid special attention to when using:

1. Redirection problem

Redirection can be judged and processed in the shouldOverrideUrlLoading method:

/ * redirect analysis: * * @ param view * @ param request * @ return true: indicates that the current url has been loaded and will not be loaded even if the url is redirected. * false: indicates that the url is handled by the system by default, and whether the redirection is still redirected The method @ RequiresApi (api = Build.VERSION_CODES.N) @ Override public boolean shouldOverrideUrlLoading (WebView view, WebResourceRequest request) {Log.d (TAG, "shouldOverrideUrlLoading new--- > url:" + request.getUrl ()) until the * / method has been loaded AnalysisRequest (request); String url = (request.getUrl ()). ToString (); boolean hasGesture = request.hasGesture (); boolean isRedirect = request.isRedirect (); return shouldOverride (view, url);}

The case to be considered for WebView redirection is as follows:

1. It is the most common http url [excluding download url such as .doc .apk]

2. Downloaded http url [e.g. .doc .apk, etc.]

3. Non-http or https custom url [such as "weixin:// alipays://, etc.]

[deprecated] if you expect to open the web page without automatically evoking app, you can judge by request.hasGesture () [whether] click, if it is true only evoke a third-party app. (this scheme is sometimes not accurate, so the following scheme can be adopted.)

[recommend] defines a Boolean value such as: isClickWeb = false, which is assigned to true in the onTouchEvent DOWN method. Add judgment in the necessary position [refer to code for details]

/ * * Custom redirect processing method * @ param view * @ param url * @ return * / private boolean shouldOverride (WebView view, final String url) {/ / Business needs can be processed by redirectionJudge (view, url) If (SchemeUtil.isHttpProtocol (url) & &! SchemeUtil.isDownloadFile (url)) {return false;} if (SchemeUtil.isHttpProtocol (url) & & SchemeUtil.isDownloadFile (url)) {if (isClickWeb) {openDialog (url); return true }} if (! SchemeUtil.isHttpProtocol (url)) {boolean isValid = SchemeUtil.isSchemeValid (context, url); if (isValid & & isClickWeb) {openDialog (url) } else {Log.d (TAG, "this scheme is not valid [for example, the app is not installed in the phone]");} return true;} return false;} 2 to achieve preloading

Resource preloading can be implemented in the shouldInterceptRequest method:

/ * * [implement preloading] * sometimes there are more resources on a page, more pictures and CSS,js, and a huge behemoth like JQuery is referenced. * it takes a long time from loading to page rendering. One solution is to package these resources into APK. * then when the page loads these resources, let it get them locally, which can increase the loading speed and reduce the pressure on the server. * / @ Nullable @ Override public WebResourceResponse shouldInterceptRequest (WebView view, WebResourceRequest request) {if (request = = null) {return null;} String url = request.getUrl () .toString (); Log.d (TAG, "shouldInterceptRequest--- >" + url); return getWebResourceResponse (url) } protected WebResourceResponse getWebResourceResponse (String url) {/ / here [tag], etc. need to negotiate with the server, and then deal with if (url.contains ("[tag]")) {try {String localPath = url.replaceFirst ("^ http.* [tag]\]", "); InputStream is = getContext (). GetAssets (). Open (localPath) Log.d (TAG, "shouldInterceptRequest: localPath" + localPath); String mimeType = "text/javascript"; if (localPath.endsWith ("css")) {mimeType = "text/css";} return new WebResourceResponse (mimeType, "UTF-8", is) } catch (IOException e) {e.printStackTrace (); return null;}} else {return null;}} 3, add error page display limit

In the onReceivedError method, request.isForMainFrame () | | url.equals () determines to reduce the display of error pages as little as possible. That is, the error page is displayed only when the error page is the main page, so as to avoid display errors in the whole page, such as a certain icon, which will affect the entire page (such as some URL of NetEase music, this situation has occurred, and error page display can be avoided in this way).

/ * when loading error pages in this method, you need to determine whether isForMainFrame is true or whether the current url is the same url as the loaded url. The method after * * @ param view * @ param request * @ param error * / Android6.0 @ RequiresApi (api = Build.VERSION_CODES.M) @ Override public void onReceivedError (WebView view, WebResourceRequest request, WebResourceError error) {super.onReceivedError (view, request, error) If (Build.VERSION.SDK_INT > = Build.VERSION_CODES.M) {String url = request.getUrl () .toString (); int errorCode = error.getErrorCode (); String description = error.getDescription () .toString () Log.d (TAG, "onReceivedError--- >" + "url:" + url + "errorCode:" + errorCode + "description:" + description + "failingUrl:" + url + "request.isForMainFrame ():" + request.isForMainFrame ()) / / if the current network request is created for main frame, the error page if (request.isForMainFrame () | | url.equals (getUrl () {showReceivedErrorPage (view, error.getErrorCode (), error.getDescription (). ToString (), request.getUrl (). ToString ()) is displayed.

When the SSL certificate is invalid, it will cause the white screen problem. You can add handler.proceed () to the onReceivedSslError method.

Can solve the problem of white screen:

/ * [solve the problem of white screen] * call * * @ param view * @ param handler * @ param error * / @ Override public void onReceivedSslError (WebView view, SslErrorHandler handler) if the SSL certificate is invalid SslError error) {/ / handle here to avoid the SSL certificate invalid page blank screen handler.proceed () Super.onReceivedSslError (view, handler, error); Log.d (TAG, "onReceivedSslError--- > error =" + error);} after reading this article, I believe you have some understanding of "sample Analysis of Android WebView basic applications". If you want to know more about it, welcome to follow the industry information channel, thank you for reading!

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