Android Dev Summit, October 23-24: two days of technical content, directly from the Android team. Sign-up for livestream updates.

WebViewCompat

public class WebViewCompat
extends Object

java.lang.Object
   ↳ androidx.webkit.WebViewCompat


Compatibility version of WebView

Summary

Nested classes

interface WebViewCompat.VisualStateCallback

Callback interface supplied to WebViewCompat.postVisualStateCallback(WebView, long, WebViewCompat.VisualStateCallback) for receiving notifications about the visual state. 

Public methods

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.

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.

static Uri getSafeBrowsingPrivacyPolicyUrl()

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

static WebChromeClient getWebChromeClient(WebView webview)

Gets the WebChromeClient.

static WebViewClient getWebViewClient(WebView webview)

Gets the WebViewClient for the WebView argument.

static WebViewRenderProcess getWebViewRenderProcess(WebView webview)

Gets the WebView renderer associated with this WebView.

static WebViewRenderProcessClient getWebViewRenderProcessClient(WebView webview)

Gets the renderer client object associated with this WebView.

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.

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

Post a message to main frame.

static void setSafeBrowsingWhitelist(List<String> hosts, ValueCallback<Boolean> callback)

Sets the list of hosts (domain names/IP addresses) that are exempt from SafeBrowsing checks.

static void setWebViewRenderProcessClient(WebView webview, Executor executor, WebViewRenderProcessClient webViewRenderProcessClient)

Sets the renderer client object associated with this WebView.

static void setWebViewRenderProcessClient(WebView webview, WebViewRenderProcessClient webViewRenderProcessClient)

Sets the renderer client object associated with this WebView.

static void startSafeBrowsing(Context context, ValueCallback<Boolean> callback)

Starts Safe Browsing initialization.

Inherited methods

Public methods

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.

Parameters
webview WebView

Returns
WebMessagePortCompat[] an array of size two, containing the two message ports that form the 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.

Parameters
context Context

Returns
PackageInfo the current WebView package, or null if there is none.

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.

Returns
Uri the url pointing to a privacy policy document which can be displayed to users.

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.

Parameters
webview WebView

Returns
WebChromeClient the WebChromeClient, or null if not yet set

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.

Parameters
webview WebView

Returns
WebViewClient the WebViewClient, or a default client if not yet set

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.

Parameters
webview WebView

Returns
WebViewRenderProcess the WebViewRenderProcess renderer handle associated with this WebView, or null if WebView is not runing in multiprocess mode.

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.

Parameters
webview WebView

Returns
WebViewRenderProcessClient the WebViewRenderProcessClient object associated with this WebView, if one has been set via setWebViewRenderProcessClient(WebView, WebViewRenderProcessClient) or null otherwise.

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
It does not include the state of:
  • 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:

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.

Parameters
webview WebView

requestId long: An id that will be returned in the callback to allow callers to match requests with callbacks.

callback WebViewCompat.VisualStateCallback: The callback to be invoked.

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.

Parameters
webview WebView

message WebMessageCompat: the WebMessage

targetOrigin Uri: the target origin.

setSafeBrowsingWhitelist

public static void setSafeBrowsingWhitelist (List<String> hosts, 
                ValueCallback<Boolean> callback)

Sets the list of hosts (domain names/IP addresses) that are exempt from SafeBrowsing checks. The list is global for all the WebViews.

Each rule should take one of these:

Rule Example Matches Subdomain
HOSTNAME example.com Yes
.HOSTNAME .example.com No
IPV4_LITERAL 192.168.1.1 No
IPV6_LITERAL_WITH_BRACKETS [10:20:30:40:50:60:70:80]No

All other rules, including wildcards, are invalid.

The correct syntax for hosts is defined by RFC 3986.

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

Parameters
hosts List: the list of hosts

callback ValueCallback: will be called with true if hosts are successfully added to the whitelist. It will be called with false if any hosts are malformed. The callback will be run on the UI thread

setWebViewRenderProcessClient

public static void setWebViewRenderProcessClient (WebView webview, 
                Executor executor, 
                WebViewRenderProcessClient webViewRenderProcessClient)

Sets the renderer client object associated with this WebView.

The renderer client encapsulates callbacks relevant to WebView renderer state. See WebViewRenderProcessClient for details.

Although many WebView instances may share a single underlying renderer, and renderers may live either in the application process, or in a sandboxed process that is isolated from the application process, instances of WebViewRenderProcessClient are set per-WebView. Callbacks represent renderer events from the perspective of this WebView, and may or may not be correlated with renderer events affecting other WebViews.

The renderer client encapsulates callbacks relevant to WebView renderer state. See WebViewRenderProcessClient for details.

Although many WebView instances may share a single underlying renderer, and renderers may live either in the application process, or in a sandboxed process that is isolated from the application process, instances of WebViewRenderProcessClient are set per-WebView. Callbacks represent renderer events from the perspective of this WebView, and may or may not be correlated with renderer events affecting other WebViews.

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

Parameters
webview WebView: the WebView on which to monitor responsiveness.

executor Executor: the Executor that will be used to execute callbacks.

webViewRenderProcessClient WebViewRenderProcessClient: the WebViewRenderProcessClient to set for callbacks.

setWebViewRenderProcessClient

public static void setWebViewRenderProcessClient (WebView webview, 
                WebViewRenderProcessClient webViewRenderProcessClient)

Sets the renderer client object associated with this WebView.

See setWebViewRenderProcessClient(WebView, Executor, WebViewRenderProcessClient) for details, with the following differences:

Callbacks will execute directly on the thread on which this WebView was instantiated.

Passing null for webViewRenderProcessClient will clear the renderer client object for this WebView.

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

Parameters
webview WebView: the WebView on which to monitor responsiveness.

webViewRenderProcessClient WebViewRenderProcessClient: the WebViewRenderProcessClient to set for callbacks.

startSafeBrowsing

public static void startSafeBrowsing (Context context, 
                ValueCallback<Boolean> callback)

Starts Safe Browsing initialization.

URL loads are not guaranteed to be protected by Safe Browsing until after callback is invoked with true. Safe Browsing is not fully supported on all devices. For those devices callback will receive false.

This should not be called if Safe Browsing has been disabled by manifest tag or WebSettings.setSafeBrowsingEnabled(boolean). This prepares resources used for Safe Browsing.

This should be called with the Application Context (and will always use the Application context to do its work regardless).

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

Parameters
context Context: Application Context.

callback ValueCallback: will be called on the UI thread with true if initialization is successful, false otherwise.