WebViewCompat

addWebMessageListener

public static void addWebMessageListener (WebView webView, 
                String jsObjectName, 
                Set<String> allowedOriginRules, 
                WebViewCompat.WebMessageListener listener)

Adds a WebViewCompat.WebMessageListener to the WebView and injects a JavaScript object into each frame that the WebViewCompat.WebMessageListener will listen on.

The injected JavaScript object will be named jsObjectName in the global scope. This will inject the JavaScript object in any frame whose origin matches allowedOriginRules for every navigation after this call, and the JavaScript object will be available immediately when the page begins to load.

Each allowedOriginRules entry must follow the format SCHEME "://" [ HOSTNAME_PATTERN [ ":" PORT ] ], each part is explained in the below table:

Note that this is a powerful API, as the JavaScript object will be injected when the frame's origin matches any one of the allowed origins. The HTTPS scheme is strongly recommended for security; allowing HTTP origins exposes the injected object to any potential network-based attackers. If a wildcard "*" is provided, it will inject the JavaScript object to all frames. A wildcard should only be used if the app wants any third party web page to be able to use the injected object. When using a wildcard, the app must treat received messages as untrustworthy and validate any data carefully.

This method can be called multiple times to inject multiple JavaScript objects.

Let's say the injected JavaScript object is named myObject. We will have following methods on that object once it is available to use:

 // Web page (in JavaScript)
 // message needs to be a JavaScript String, MessagePorts is an optional parameter.
 myObject.postMessage(message[, MessagePorts])

 // To receive messages posted from the app side, assign a function to the "onmessage"
 // property. This function should accept a single "event" argument. "event" has a "data"
 // property, which is the message string from the app side.
 myObject.onmessage = function(event) { ... }

 // To be compatible with DOM EventTarget's addEventListener, it accepts type and listener
 // parameters, where type can be only "message" type and listener can only be a JavaScript
 // function for myObject. An event object will be passed to listener with a "data" property,
 // which is the message string from the app side.
 myObject.addEventListener(type, listener)

 // To be compatible with DOM EventTarget's removeEventListener, it accepts type and listener
 // parameters, where type can be only "message" type and listener can only be a JavaScript
 // function for myObject.
 myObject.removeEventListener(type, listener)
 

We start the communication between JavaScript and the app from the JavaScript side. In order to send message from the app to JavaScript, it needs to post a message from JavaScript first, so the app will have a JavaScriptReplyProxy object to respond. Example:

 // Web page (in JavaScript)
 myObject.onmessage = function(event) {
   // prints "Got it!" when we receive the app's response.
   console.log(event.data);
 }
 myObject.postMessage("I'm ready!");
 

 // App (in Java)
 WebMessageListener myListener = new WebMessageListener() {
   @Override
   public void onPostMessage(WebView view, WebMessageCompat message, Uri sourceOrigin,
            boolean isMainFrame, JavaScriptReplyProxy replyProxy) {
     // do something about view, message, sourceOrigin and isMainFrame.
     replyProxy.postMessage("Got it!");
   }
 };
 if (WebViewFeature.isFeatureSupported(WebViewFeature.WEB_MESSAGE_LISTENER)) {
   WebViewCompat.addWebMessageListener(webView, "myObject", rules, myListener);
 }
 

This method should only be called if WebViewFeature.isFeatureSupported(String) returns true for WebViewFeature.WEB_MESSAGE_LISTENER.

createWebMessageChannel

public static WebMessagePortCompat[] createWebMessageChannel (WebView webview)

Creates a message channel to communicate with JS and returns the message ports that represent the endpoints of this message channel. The HTML5 message channel functionality is described here

The returned message channels are entangled and already in started state.

This method should only be called if WebViewFeature.isFeatureSupported(String) returns true for WebViewFeature.CREATE_WEB_MESSAGE_CHANNEL.

getCurrentWebViewPackage

public static PackageInfo getCurrentWebViewPackage (Context context)

If WebView has already been loaded into the current process this method will return the package that was used to load it. Otherwise, the package that would be used if the WebView was loaded right now will be returned; this does not cause WebView to be loaded, so this information may become outdated at any time. The WebView package changes either when the current WebView package is updated, disabled, or uninstalled. It can also be changed through a Developer Setting. If the WebView package changes, any app process that has loaded WebView will be killed. The next time the app starts and loads WebView it will use the new WebView package instead.

getSafeBrowsingPrivacyPolicyUrl

public static Uri getSafeBrowsingPrivacyPolicyUrl ()

Returns a URL pointing to the privacy policy for Safe Browsing reporting.

This method should only be called if WebViewFeature.isFeatureSupported(String) returns true for WebViewFeature.SAFE_BROWSING_PRIVACY_POLICY_URL.

getWebChromeClient

public static WebChromeClient getWebChromeClient (WebView webview)

Gets the WebChromeClient.

This method should only be called if WebViewFeature.isFeatureSupported(String) returns true for WebViewFeature.GET_WEB_CHROME_CLIENT.

getWebViewClient

public static WebViewClient getWebViewClient (WebView webview)

Gets the WebViewClient for the WebView argument.

This method should only be called if WebViewFeature.isFeatureSupported(String) returns true for WebViewFeature.GET_WEB_VIEW_CLIENT.

getWebViewRenderProcess

public static WebViewRenderProcess getWebViewRenderProcess (WebView webview)

Gets the WebView renderer associated with this WebView.

In Android O and above, WebView may run in "multiprocess" mode. In multiprocess mode, rendering of web content is performed by a sandboxed renderer process separate to the application process. This renderer process may be shared with other WebViews in the application, but is not shared with other application processes.

If WebView is running in multiprocess mode, this method returns a handle to the renderer process associated with the WebView, which can be used to control the renderer process.

This method should only be called if WebViewFeature.isFeatureSupported(String) returns true for WebViewFeature.GET_WEB_VIEW_RENDERER.

getWebViewRenderProcessClient

public static WebViewRenderProcessClient getWebViewRenderProcessClient (WebView webview)

Gets the renderer client object associated with this WebView.

This method should only be called if WebViewFeature.isFeatureSupported(String) returns true for WebViewFeature.WEB_VIEW_RENDERER_CLIENT_BASIC_USAGE.

isMultiProcessEnabled

public static boolean isMultiProcessEnabled ()

Returns true if WebView is running in multi process mode.

In Android O and above, WebView may run in "multiprocess" mode. In multiprocess mode, rendering of web content is performed by a sandboxed renderer process separate to the application process. This renderer process may be shared with other WebViews in the application, but is not shared with other application processes.

postVisualStateCallback

public static void postVisualStateCallback (WebView webview, 
                long requestId, 
                WebViewCompat.VisualStateCallback callback)

Posts a WebViewCompat.VisualStateCallback, which will be called when the current state of the WebView is ready to be drawn.

Because updates to the DOM are processed asynchronously, updates to the DOM may not immediately be reflected visually by subsequent WebView.onDraw(Canvas) invocations. The WebViewCompat.VisualStateCallback provides a mechanism to notify the caller when the contents of the DOM at the current time are ready to be drawn the next time the WebView draws.

The next draw after the callback completes is guaranteed to reflect all the updates to the DOM up to the point at which the WebViewCompat.VisualStateCallback was posted, but it may also contain updates applied after the callback was posted.

The state of the DOM covered by this API includes the following:

• primitive HTML elements (div, img, span, etc..)
• images
• CSS animations
• WebGL
• canvas

• the video tag

To guarantee that the WebView will successfully render the first frame after the WebViewCompat.VisualStateCallback.onComplete(long) method has been called a set of conditions must be met:

• If the WebView's visibility is set to VISIBLE then * the WebView must be attached to the view hierarchy.
• If the WebView's visibility is set to INVISIBLE then the WebView must be attached to the view hierarchy and must be made VISIBLE from the WebViewCompat.VisualStateCallback.onComplete(long) method.
• If the WebView's visibility is set to GONE then the WebView must be attached to the view hierarchy and its LayoutParams's width and height need to be set to fixed values and must be made VISIBLE from the WebViewCompat.VisualStateCallback.onComplete(long) method.

When using this API it is also recommended to enable pre-rasterization if the WebView is off screen to avoid flickering. See WebSettings.setOffscreenPreRaster(boolean) for more details and do consider its caveats.

This method should only be called if WebViewFeature.isFeatureSupported(String) returns true for WebViewFeature.VISUAL_STATE_CALLBACK.

postWebMessage

public static void postWebMessage (WebView webview, 
                WebMessageCompat message, 
                Uri targetOrigin)

Post a message to main frame. The embedded application can restrict the messages to a certain target origin. See HTML5 spec for how target origin can be used.

A target origin can be set as a wildcard ("*"). However this is not recommended. See the page above for security issues.

This method should only be called if WebViewFeature.isFeatureSupported(String) returns true for WebViewFeature.POST_WEB_MESSAGE.

removeWebMessageListener

public static void removeWebMessageListener (WebView webview, 
                String jsObjectName)

Removes the WebMessageListener associated with jsObjectName.

Note that after this call, the injected JavaScript object is still in the JavaScript context, however any message sent after this call won't reach the WebMessageListener.

This method should only be called if WebViewFeature.isFeatureSupported(String) returns true for WebViewFeature.WEB_MESSAGE_LISTENER.