android/webkit/WebViewClient.java

/*
 * Copyright (C) 2008 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.webkit;

import android.graphics.Bitmap;
import android.net.http.SslError;
import android.os.Message;
import android.view.InputEvent;
import android.view.KeyEvent;
import android.view.ViewRootImpl;

public class WebViewClient {

    /**
     * Give the host application a chance to take over the control when a new
     * url is about to be loaded in the current WebView. If WebViewClient is not
     * provided, by default WebView will ask Activity Manager to choose the
     * proper handler for the url. If WebViewClient is provided, return true
     * means the host application handles the url, while return false means the
     * current WebView handles the url.
     * This method is not called for requests using the POST "method".
     *
     * @param view The WebView that is initiating the callback.
     * @param url The url to be loaded.
     * @return True if the host application wants to leave the current WebView
     *         and handle the url itself, otherwise return false.
     */
    public boolean shouldOverrideUrlLoading(WebView view, String url) {
        return false;
    }

    /**
     * Notify the host application that a page has started loading. This method
     * is called once for each main frame load so a page with iframes or
     * framesets will call onPageStarted one time for the main frame. This also
     * means that onPageStarted will not be called when the contents of an
     * embedded frame changes, i.e. clicking a link whose target is an iframe,
     * it will also not be called for fragment navigations (navigations to
     * #fragment_id).
     *
     * @param view The WebView that is initiating the callback.
     * @param url The url to be loaded.
     * @param favicon The favicon for this page if it already exists in the
     *            database.
     */
    public void onPageStarted(WebView view, String url, Bitmap favicon) {
    }

    /**
     * Notify the host application that a page has finished loading. This method
     * is called only for main frame. When onPageFinished() is called, the
     * rendering picture may not be updated yet. To get the notification for the
     * new Picture, use {@link WebView.PictureListener#onNewPicture}.
     *
     * @param view The WebView that is initiating the callback.
     * @param url The url of the page.
     */
    public void onPageFinished(WebView view, String url) {
    }

    /**
     * Notify the host application that the WebView will load the resource
     * specified by the given url.
     *
     * @param view The WebView that is initiating the callback.
     * @param url The url of the resource the WebView will load.
     */
    public void onLoadResource(WebView view, String url) {
    }

    /**
     * Notify the host application that {@link android.webkit.WebView} content left over from
     * previous page navigations will no longer be drawn.
     *
     * <p>This callback can be used to determine the point at which it is safe to make a recycled
     * {@link android.webkit.WebView} visible, ensuring that no stale content is shown. It is called
     * at the earliest point at which it can be guaranteed that {@link WebView#onDraw} will no
     * longer draw any content from previous navigations. The next draw will display either the
     * {@link WebView#setBackgroundColor background color} of the {@link WebView}, or some of the
     * contents of the newly loaded page.
     *
     * <p>This method is called when the body of the HTTP response has started loading, is reflected
     * in the DOM, and will be visible in subsequent draws. This callback occurs early in the
     * document loading process, and as such you should expect that linked resources (for example,
     * css and images) may not be available.</p>
     *
     * <p>For more fine-grained notification of visual state updates, see {@link
     * WebView#postVisualStateCallback}.</p>
     *
     * <p>Please note that all the conditions and recommendations applicable to
     * {@link WebView#postVisualStateCallback} also apply to this API.<p>
     *
     * <p>This callback is only called for main frame navigations.</p>
     *
     * @param view The {@link android.webkit.WebView} for which the navigation occurred.
     * @param url  The URL corresponding to the page navigation that triggered this callback.
     */
    public void onPageCommitVisible(WebView view, String url) {
    }

    /**
     * Notify the host application of a resource request and allow the
     * application to return the data.  If the return value is null, the WebView
     * will continue to load the resource as usual.  Otherwise, the return
     * response and data will be used.  NOTE: This method is called on a thread
     * other than the UI thread so clients should exercise caution
     * when accessing private data or the view system.
     *
     * @param view The {@link android.webkit.WebView} that is requesting the
     *             resource.
     * @param url The raw url of the resource.
     * @return A {@link android.webkit.WebResourceResponse} containing the
     *         response information or null if the WebView should load the
     *         resource itself.
     * @deprecated Use {@link #shouldInterceptRequest(WebView, WebResourceRequest)
     *             shouldInterceptRequest(WebView, WebResourceRequest)} instead.
     */
    @Deprecated
    public WebResourceResponse shouldInterceptRequest(WebView view,
            String url) {
        return null;
    }

    /**
     * Notify the host application of a resource request and allow the
     * application to return the data.  If the return value is null, the WebView
     * will continue to load the resource as usual.  Otherwise, the return
     * response and data will be used.  NOTE: This method is called on a thread
     * other than the UI thread so clients should exercise caution
     * when accessing private data or the view system.
     *
     * @param view The {@link android.webkit.WebView} that is requesting the
     *             resource.
     * @param request Object containing the details of the request.
     * @return A {@link android.webkit.WebResourceResponse} containing the
     *         response information or null if the WebView should load the
     *         resource itself.
     */
    public WebResourceResponse shouldInterceptRequest(WebView view,
            WebResourceRequest request) {
        return shouldInterceptRequest(view, request.getUrl().toString());
    }

    /**
     * Notify the host application that there have been an excessive number of
     * HTTP redirects. As the host application if it would like to continue
     * trying to load the resource. The default behavior is to send the cancel
     * message.
     *
     * @param view The WebView that is initiating the callback.
     * @param cancelMsg The message to send if the host wants to cancel
     * @param continueMsg The message to send if the host wants to continue
     * @deprecated This method is no longer called. When the WebView encounters
     *             a redirect loop, it will cancel the load.
     */
    @Deprecated
    public void onTooManyRedirects(WebView view, Message cancelMsg,
            Message continueMsg) {
        cancelMsg.sendToTarget();
    }

    // These ints must match up to the hidden values in EventHandler.
    /** Generic error */
    public static final int ERROR_UNKNOWN = -1;
    /** Server or proxy hostname lookup failed */
    public static final int ERROR_HOST_LOOKUP = -2;
    /** Unsupported authentication scheme (not basic or digest) */
    public static final int ERROR_UNSUPPORTED_AUTH_SCHEME = -3;
    /** User authentication failed on server */
    public static final int ERROR_AUTHENTICATION = -4;
    /** User authentication failed on proxy */
    public static final int ERROR_PROXY_AUTHENTICATION = -5;
    /** Failed to connect to the server */
    public static final int ERROR_CONNECT = -6;
    /** Failed to read or write to the server */
    public static final int ERROR_IO = -7;
    /** Connection timed out */
    public static final int ERROR_TIMEOUT = -8;
    /** Too many redirects */
    public static final int ERROR_REDIRECT_LOOP = -9;
    /** Unsupported URI scheme */
    public static final int ERROR_UNSUPPORTED_SCHEME = -10;
    /** Failed to perform SSL handshake */
    public static final int ERROR_FAILED_SSL_HANDSHAKE = -11;
    /** Malformed URL */
    public static final int ERROR_BAD_URL = -12;
    /** Generic file error */
    public static final int ERROR_FILE = -13;
    /** File not found */
    public static final int ERROR_FILE_NOT_FOUND = -14;
    /** Too many requests during this load */
    public static final int ERROR_TOO_MANY_REQUESTS = -15;

    /**
     * Report an error to the host application. These errors are unrecoverable
     * (i.e. the main resource is unavailable). The errorCode parameter
     * corresponds to one of the ERROR_* constants.
     * @param view The WebView that is initiating the callback.
     * @param errorCode The error code corresponding to an ERROR_* value.
     * @param description A String describing the error.
     * @param failingUrl The url that failed to load.
     * @deprecated Use {@link #onReceivedError(WebView, WebResourceRequest, WebResourceError)
     *             onReceivedError(WebView, WebResourceRequest, WebResourceError)} instead.
     */
    @Deprecated
    public void onReceivedError(WebView view, int errorCode,
            String description, String failingUrl) {
    }

    /**
     * Report web resource loading error to the host application. These errors usually indicate
     * inability to connect to the server. Note that unlike the deprecated version of the callback,
     * the new version will be called for any resource (iframe, image, etc), not just for the main
     * page. Thus, it is recommended to perform minimum required work in this callback.
     * @param view The WebView that is initiating the callback.
     * @param request The originating request.
     * @param error Information about the error occured.
     */
    public void onReceivedError(WebView view, WebResourceRequest request, WebResourceError error) {
        if (request.isForMainFrame()) {
            onReceivedError(view,
                    error.getErrorCode(), error.getDescription().toString(),
                    request.getUrl().toString());
        }
    }

    /**
     * Notify the host application that an HTTP error has been received from the server while
     * loading a resource.  HTTP errors have status codes &gt;= 400.  This callback will be called
     * for any resource (iframe, image, etc), not just for the main page. Thus, it is recommended to
     * perform minimum required work in this callback. Note that the content of the server
     * response may not be provided within the <b>errorResponse</b> parameter.
     * @param view The WebView that is initiating the callback.
     * @param request The originating request.
     * @param errorResponse Information about the error occured.
     */
    public void onReceivedHttpError(
            WebView view, WebResourceRequest request, WebResourceResponse errorResponse) {
    }

    /**
     * As the host application if the browser should resend data as the
     * requested page was a result of a POST. The default is to not resend the
     * data.
     *
     * @param view The WebView that is initiating the callback.
     * @param dontResend The message to send if the browser should not resend
     * @param resend The message to send if the browser should resend data
     */
    public void onFormResubmission(WebView view, Message dontResend,
            Message resend) {
        dontResend.sendToTarget();
    }

    /**
     * Notify the host application to update its visited links database.
     *
     * @param view The WebView that is initiating the callback.
     * @param url The url being visited.
     * @param isReload True if this url is being reloaded.
     */
    public void doUpdateVisitedHistory(WebView view, String url,
            boolean isReload) {
    }

    /**
     * Notify the host application that an SSL error occurred while loading a
     * resource. The host application must call either handler.cancel() or
     * handler.proceed(). Note that the decision may be retained for use in
     * response to future SSL errors. The default behavior is to cancel the
     * load.
     *
     * @param view The WebView that is initiating the callback.
     * @param handler An SslErrorHandler object that will handle the user's
     *            response.
     * @param error The SSL error object.
     */
    public void onReceivedSslError(WebView view, SslErrorHandler handler,
            SslError error) {
        handler.cancel();
    }

    /**
     * Notify the host application to handle a SSL client certificate
     * request. The host application is responsible for showing the UI
     * if desired and providing the keys. There are three ways to
     * respond: proceed(), cancel() or ignore(). Webview stores the response
     * in memory (for the life of the application) if proceed() or cancel() is
     * called and does not call onReceivedClientCertRequest() again for the
     * same host and port pair. Webview does not store the response if ignore()
     * is called.
     *
     * This method is called on the UI thread. During the callback, the
     * connection is suspended.
     *
     * For most use cases, the application program should implement the
     * {@link android.security.KeyChainAliasCallback} interface and pass it to
     * {@link android.security.KeyChain#choosePrivateKeyAlias} to start an
     * activity for the user to choose the proper alias. The keychain activity will
     * provide the alias through the callback method in the implemented interface. Next
     * the application should create an async task to call
     * {@link android.security.KeyChain#getPrivateKey} to receive the key.
     *
     * An example implementation of client certificates can be seen at
     * <A href="https://android.googlesource.com/platform/packages/apps/Browser/+/android-5.1.1_r1/src/com/android/browser/Tab.java">
     * AOSP Browser</a>
     *
     * The default behavior is to cancel, returning no client certificate.
     *
     * @param view The WebView that is initiating the callback
     * @param request An instance of a {@link ClientCertRequest}
     *
     */
    public void onReceivedClientCertRequest(WebView view, ClientCertRequest request) {
        request.cancel();
    }

    /**
     * Notifies the host application that the WebView received an HTTP
     * authentication request. The host application can use the supplied
     * {@link HttpAuthHandler} to set the WebView's response to the request.
     * The default behavior is to cancel the request.
     *
     * @param view the WebView that is initiating the callback
     * @param handler the HttpAuthHandler used to set the WebView's response
     * @param host the host requiring authentication
     * @param realm the realm for which authentication is required
     * @see WebView#getHttpAuthUsernamePassword
     */
    public void onReceivedHttpAuthRequest(WebView view,
            HttpAuthHandler handler, String host, String realm) {
        handler.cancel();
    }

    /**
     * Give the host application a chance to handle the key event synchronously.
     * e.g. menu shortcut key events need to be filtered this way. If return
     * true, WebView will not handle the key event. If return false, WebView
     * will always handle the key event, so none of the super in the view chain
     * will see the key event. The default behavior returns false.
     *
     * @param view The WebView that is initiating the callback.
     * @param event The key event.
     * @return True if the host application wants to handle the key event
     *         itself, otherwise return false
     */
    public boolean shouldOverrideKeyEvent(WebView view, KeyEvent event) {
        return false;
    }

    /**
     * Notify the host application that a key was not handled by the WebView.
     * Except system keys, WebView always consumes the keys in the normal flow
     * or if shouldOverrideKeyEvent returns true. This is called asynchronously
     * from where the key is dispatched. It gives the host application a chance
     * to handle the unhandled key events.
     *
     * @param view The WebView that is initiating the callback.
     * @param event The key event.
     * @deprecated This method is subsumed by the more generic onUnhandledInputEvent.
     */
    @Deprecated
    public void onUnhandledKeyEvent(WebView view, KeyEvent event) {
        onUnhandledInputEventInternal(view, event);
    }

    /**
     * Notify the host application that a input event was not handled by the WebView.
     * Except system keys, WebView always consumes input events in the normal flow
     * or if shouldOverrideKeyEvent returns true. This is called asynchronously
     * from where the event is dispatched. It gives the host application a chance
     * to handle the unhandled input events.
     *
     * Note that if the event is a {@link android.view.MotionEvent}, then it's lifetime is only
     * that of the function call. If the WebViewClient wishes to use the event beyond that, then it
     * <i>must</i> create a copy of the event.
     *
     * It is the responsibility of overriders of this method to call
     * {@link #onUnhandledKeyEvent(WebView, KeyEvent)}
     * when appropriate if they wish to continue receiving events through it.
     *
     * @param view The WebView that is initiating the callback.
     * @param event The input event.
     */
    public void onUnhandledInputEvent(WebView view, InputEvent event) {
        if (event instanceof KeyEvent) {
            onUnhandledKeyEvent(view, (KeyEvent) event);
            return;
        }
        onUnhandledInputEventInternal(view, event);
    }

    private void onUnhandledInputEventInternal(WebView view, InputEvent event) {
        ViewRootImpl root = view.getViewRootImpl();
        if (root != null) {
            root.dispatchUnhandledInputEvent(event);
        }
    }

    /**
     * Notify the host application that the scale applied to the WebView has
     * changed.
     *
     * @param view he WebView that is initiating the callback.
     * @param oldScale The old scale factor
     * @param newScale The new scale factor
     */
    public void onScaleChanged(WebView view, float oldScale, float newScale) {
    }

    /**
     * Notify the host application that a request to automatically log in the
     * user has been processed.
     * @param view The WebView requesting the login.
     * @param realm The account realm used to look up accounts.
     * @param account An optional account. If not null, the account should be
     *                checked against accounts on the device. If it is a valid
     *                account, it should be used to log in the user.
     * @param args Authenticator specific arguments used to log in the user.
     */
    public void onReceivedLoginRequest(WebView view, String realm,
            String account, String args) {
    }
}