webkit下的WebChromeClient

下面摘自开源中国社区WebChromeClient的源码，官方对方法作用和参数的解释非常详细，直接看英文注释理解更深刻，就不翻译了：

WebChromeClient：

/** * 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.content.pm.ActivityInfo;import android.graphics.Bitmap;import android.net.Uri;import android.os.Message;import android.view.View;public class WebChromeClient {    /***     * Tell the host application the current progress of loading a page.     * @param view The WebView that initiated the callback.     * @param newProgress Current page loading progress, represented by     *                    an integer between 0 and 100.     */    public void onProgressChanged(WebView view, int newProgress) {}    /***     * Notify the host application of a change in the document title.     * @param view The WebView that initiated the callback.     * @param title A String containing the new title of the document.     */    public void onReceivedTitle(WebView view, String title) {}    /***     * Notify the host application of a new favicon for the current page.     * @param view The WebView that initiated the callback.     * @param icon A Bitmap containing the favicon for the current page.     */    public void onReceivedIcon(WebView view, Bitmap icon) {}    /***     * Notify the host application of the url for an apple-touch-icon.     * @param view The WebView that initiated the callback.     * @param url The icon url.     * @param precomposed True if the url is for a precomposed touch icon.     */    public void onReceivedTouchIconUrl(WebView view, String url,            boolean precomposed) {}    /***     * A callback interface used by the host application to notify     * the current page that its custom view has been dismissed.     */    public interface CustomViewCallback {        /***         * Invoked when the host application dismisses the         * custom view.         */        public void onCustomViewHidden();    }    /***     * Notify the host application that the current page would     * like to show a custom View.     * @param view is the View object to be shown.     * @param callback is the callback to be invoked if and when the view     * is dismissed.     */    public void onShowCustomView(View view, CustomViewCallback callback) {};    /***     * Notify the host application that the current page would     * like to show a custom View in a particular orientation.     * @param view is the View object to be shown.     * @param requestedOrientation An orientation constant as used in     * {@link ActivityInfo#screenOrientation ActivityInfo.screenOrientation}.     * @param callback is the callback to be invoked if and when the view     * is dismissed.     */    public void onShowCustomView(View view, int requestedOrientation,            CustomViewCallback callback) {};        /***     * Notify the host application that the current page would     * like to hide its custom view.     */    public void onHideCustomView() {}    /***     * Request the host application to create a new Webview. The host     * application should handle placement of the new WebView in the view     * system. The default behavior returns null.     * @param view The WebView that initiated the callback.     * @param dialog True if the new window is meant to be a small dialog     *               window.     * @param userGesture True if the request was initiated by a user gesture     *                    such as clicking a link.     * @param resultMsg The message to send when done creating a new WebView.     *                  Set the new WebView through resultMsg.obj which is      *                  WebView.WebViewTransport() and then call     *                  resultMsg.sendToTarget();     * @return Similar to javscript dialogs, this method should return true if     *         the client is going to handle creating a new WebView. Note that     *         the WebView will halt processing if this method returns true so     *         make sure to call resultMsg.sendToTarget(). It is undefined     *         behavior to call resultMsg.sendToTarget() after returning false     *         from this method.     */    public boolean onCreateWindow(WebView view, boolean dialog,            boolean userGesture, Message resultMsg) {        return false;    }    /***     * Request display and focus for this WebView. This may happen due to     * another WebView opening a link in this WebView and requesting that this     * WebView be displayed.     * @param view The WebView that needs to be focused.     */    public void onRequestFocus(WebView view) {}    /***     * Notify the host application to close the given WebView and remove it     * from the view system if necessary. At this point, WebCore has stopped     * any loading in this window and has removed any cross-scripting ability     * in javascript.     * @param window The WebView that needs to be closed.     */    public void onCloseWindow(WebView window) {}    /***     * Tell the client to display a javascript alert dialog.  If the client     * returns true, WebView will assume that the client will handle the     * dialog.  If the client returns false, it will continue execution.     * @param view The WebView that initiated the callback.     * @param url The url of the page requesting the dialog.     * @param message Message to be displayed in the window.     * @param result A JsResult to confirm that the user hit enter.     * @return boolean Whether the client will handle the alert dialog.     */    public boolean onJsAlert(WebView view, String url, String message,            JsResult result) {        return false;    }    /***     * Tell the client to display a confirm dialog to the user. If the client     * returns true, WebView will assume that the client will handle the     * confirm dialog and call the appropriate JsResult method. If the     * client returns false, a default value of false will be returned to     * javascript. The default behavior is to return false.     * @param view The WebView that initiated the callback.     * @param url The url of the page requesting the dialog.     * @param message Message to be displayed in the window.     * @param result A JsResult used to send the user's response to     *               javascript.     * @return boolean Whether the client will handle the confirm dialog.     */    public boolean onJsConfirm(WebView view, String url, String message,            JsResult result) {        return false;    }    /***     * Tell the client to display a prompt dialog to the user. If the client     * returns true, WebView will assume that the client will handle the     * prompt dialog and call the appropriate JsPromptResult method. If the     * client returns false, a default value of false will be returned to to     * javascript. The default behavior is to return false.     * @param view The WebView that initiated the callback.     * @param url The url of the page requesting the dialog.     * @param message Message to be displayed in the window.     * @param defaultValue The default value displayed in the prompt dialog.     * @param result A JsPromptResult used to send the user's reponse to     *               javascript.     * @return boolean Whether the client will handle the prompt dialog.     */    public boolean onJsPrompt(WebView view, String url, String message,            String defaultValue, JsPromptResult result) {        return false;    }    /***     * Tell the client to display a dialog to confirm navigation away from the     * current page. This is the result of the onbeforeunload javascript event.     * If the client returns true, WebView will assume that the client will     * handle the confirm dialog and call the appropriate JsResult method. If     * the client returns false, a default value of true will be returned to     * javascript to accept navigation away from the current page. The default     * behavior is to return false. Setting the JsResult to true will navigate     * away from the current page, false will cancel the navigation.     * @param view The WebView that initiated the callback.     * @param url The url of the page requesting the dialog.     * @param message Message to be displayed in the window.     * @param result A JsResult used to send the user's response to     *               javascript.     * @return boolean Whether the client will handle the confirm dialog.     */    public boolean onJsBeforeUnload(WebView view, String url, String message,            JsResult result) {        return false;    }   /***    * Tell the client that the database quota for the origin has been exceeded.    * @param url The URL that triggered the notification    * @param databaseIdentifier The identifier of the database that caused the    *     quota overflow.    * @param currentQuota The current quota for the origin.    * @param estimatedSize The estimated size of the database.    * @param totalUsedQuota is the sum of all origins' quota.    * @param quotaUpdater A callback to inform the WebCore thread that a new    *     quota is available. This callback must always be executed at some    *     point to ensure that the sleeping WebCore thread is woken up.    */    public void onExceededDatabaseQuota(String url, String databaseIdentifier,        long currentQuota, long estimatedSize, long totalUsedQuota,        WebStorage.QuotaUpdater quotaUpdater) {        // This default implementation passes the current quota back to WebCore.        // WebCore will interpret this that new quota was declined.        quotaUpdater.updateQuota(currentQuota);    }   /***    * Tell the client that the Application Cache has exceeded its max size.    * @param spaceNeeded is the amount of disk space that would be needed    * in order for the last appcache operation to succeed.    * @param totalUsedQuota is the sum of all origins' quota.    * @param quotaUpdater A callback to inform the WebCore thread that a new    * app cache size is available. This callback must always be executed at    * some point to ensure that the sleeping WebCore thread is woken up.    */    public void onReachedMaxAppCacheSize(long spaceNeeded, long totalUsedQuota,            WebStorage.QuotaUpdater quotaUpdater) {        quotaUpdater.updateQuota(0);    }    /***     * Instructs the client to show a prompt to ask the user to set the     * Geolocation permission state for the specified origin.     */    public void onGeolocationPermissionsShowPrompt(String origin,            GeolocationPermissions.Callback callback) {}    /***     * Instructs the client to hide the Geolocation permissions prompt.     */    public void onGeolocationPermissionsHidePrompt() {}    /***     * Tell the client that a JavaScript execution timeout has occured. And the     * client may decide whether or not to interrupt the execution. If the     * client returns true, the JavaScript will be interrupted. If the client     * returns false, the execution will continue. Note that in the case of     * continuing execution, the timeout counter will be reset, and the callback     * will continue to occur if the script does not finish at the next check     * point.     * @return boolean Whether the JavaScript execution should be interrupted.     */    public boolean onJsTimeout() {        return true;    }    /***     * Report a JavaScript error message to the host application. The ChromeClient     * should override this to process the log message as they see fit.     * @param message The error message to report.     * @param lineNumber The line number of the error.     * @param sourceID The name of the source file that caused the error.     * @deprecated Use {@link #onConsoleMessage(ConsoleMessage) onConsoleMessage(ConsoleMessage)}     *      instead.     */    @Deprecated    public void onConsoleMessage(String message, int lineNumber, String sourceID) { }    /***     * Report a JavaScript console message to the host application. The ChromeClient     * should override this to process the log message as they see fit.     * @param consoleMessage Object containing details of the console message.     * @return true if the message is handled by the client.     */    public boolean onConsoleMessage(ConsoleMessage consoleMessage) {        // Call the old version of this function for backwards compatability.        onConsoleMessage(consoleMessage.message(), consoleMessage.lineNumber(),                consoleMessage.sourceId());        return false;    }    /***     * When not playing, video elements are represented by a 'poster' image. The     * image to use can be specified by the poster attribute of the video tag in     * HTML. If the attribute is absent, then a default poster will be used. This     * method allows the ChromeClient to provide that default image.     *     * @return Bitmap The image to use as a default poster, or null if no such image is     * available.     */    public Bitmap getDefaultVideoPoster() {        return null;    }    /***     * When the user starts to playback a video element, it may take time for enough     * data to be buffered before the first frames can be rendered. While this buffering     * is taking place, the ChromeClient can use this function to provide a View to be     * displayed. For example, the ChromeClient could show a spinner animation.     *     * @return View The View to be displayed whilst the video is loading.     */    public View getVideoLoadingProgressView() {        return null;    }    /*** Obtains a list of all visited history items, used for link coloring     */    public void getVisitedHistory(ValueCallback<String[]> callback) {    }    /***     * Tell the client to open a file chooser.     * @param uploadFile A ValueCallback to set the URI of the file to upload.     *      onReceiveValue must be called to wake up the thread.a     * @param acceptType The value of the 'accept' attribute of the input tag     *         associated with this file picker.     * @hide     */    public void openFileChooser(ValueCallback<Uri> uploadFile, String acceptType) {        uploadFile.onReceiveValue(null);    }    /***     * Tell the client that the page being viewed is web app capable,     * i.e. has specified the fullscreen-web-app-capable meta tag.     * @hide     */    public void setInstallableWebApp() { }    /***     * Tell the client that the page being viewed has an autofillable     * form and the user would like to set a profile up.     * @param msg A Message to send once the user has successfully     *      set up a profile and to inform the WebTextView it should     *      now autofill using that new profile.     * @hide     */    public void setupAutoFill(Message msg) { }}