关于Android HTML5 audio autoplay无效问题的解决方案

WebView webView = this.finishActivity(R.id.main_act_webview);
// ... ...
// 其他配置
// ... ...
// 设置4.2以后版本支持autoPlay，非用户手势促发
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {
webView.getSettings().setMediaPlaybackRequiresUserGesture(false);
}

/**
* Gets the WebSettings object used to control the settings for this
* WebView.
*
* @return a WebSettings object that can be used to control this WebView's
* settings
*/
public WebSettings getSettings() {
checkThread();
return mProvider.getSettings();
}

/**
* @hide
*/
@SuppressWarnings("deprecation") // for super() call into deprecated base class constructor.
protected WebView(Context context,AttributeSet attrs,int defStyleAttr,int defStyleRes,Map<String,Object> javaScriptInterfaces,boolean privateBrowsing) {
super(context,attrs,defStyleAttr,defStyleRes);
if (context == null) {
throw new IllegalArgumentException("Invalid context argument");
}
sEnforceThreadChecking = context.getApplicationInfo().targetSdkVersion >=
Build.VERSION_CODES.JELLY_BEAN_MR2;
checkThread();
ensureProviderCreated();
mProvider.init(javaScriptInterfaces,privateBrowsing);
// Post condition of creating a webview is the CookieSyncManager.getInstance() is allowed.
CookieSyncManager.setGetInstanceIsAllowed();
}

private void ensureProviderCreated() {
checkThread();
if (mProvider == null) {
// As this can get called during the base class constructor chain,pass the minimum
// number of dependencies here; the rest are deferred to init().
mProvider = getFactory().createWebView(this,new PrivateAccess());
}
}

static WebViewFactoryProvider getProvider() {
synchronized (sProviderLock) {
// For now the main purpose of this function (and the factory abstraction) is to keep
// us honest and minimize usage of WebView internals when binding the proxy.
if (sProviderInstance != null) return sProviderInstance;
final int uid = android.os.Process.myUid();
if (uid == android.os.Process.ROOT_UID || uid == android.os.Process.SYSTEM_UID) {
throw new UnsupportedOperationException(
"For security reasons,WebView is not allowed in privileged processes");
}
Trace.traceBegin(Trace.TRACE_TAG_WEBVIEW,"WebViewFactory.getProvider()");
try {
Class<WebViewFactoryProvider> providerClass = getProviderClass();
StrictMode.ThreadPolicy oldPolicy = StrictMode.allowThreadDiskReads();
Trace.traceBegin(Trace.TRACE_TAG_WEBVIEW,"providerClass.newInstance()");
try {
sProviderInstance = providerClass.getConstructor(WebViewDelegate.class)
.newInstance(new WebViewDelegate());
if (DEBUG) Log.v(LOGTAG,"Loaded provider: " + sProviderInstance);
return sProviderInstance;
} catch (Exception e) {
Log.e(LOGTAG,"error instantiating provider",e);
throw new AndroidRuntimeException(e);
} finally {
Trace.traceEnd(Trace.TRACE_TAG_WEBVIEW);
StrictMode.setThreadPolicy(oldPolicy);
}
} finally {
Trace.traceEnd(Trace.TRACE_TAG_WEBVIEW);
}
}
}

private static Class<WebViewFactoryProvider> getProviderClass() {
try {
// First fetch the package info so we can log the webview package version.
sPackageInfo = fetchPackageInfo();
Log.i(LOGTAG,"Loading " + sPackageInfo.packageName + " version " +
sPackageInfo.versionName + " (code " + sPackageInfo.versionCode + ")");
Trace.traceBegin(Trace.TRACE_TAG_WEBVIEW,"WebViewFactory.loadNativeLibrary()");
loadNativeLibrary();
Trace.traceEnd(Trace.TRACE_TAG_WEBVIEW);
Trace.traceBegin(Trace.TRACE_TAG_WEBVIEW,"WebViewFactory.getChromiumProviderClass()");
try {
return getChromiumProviderClass();
} catch (ClassNotFoundException e) {
Log.e(LOGTAG,"error loading provider",e);
throw new AndroidRuntimeException(e);
} finally {
Trace.traceEnd(Trace.TRACE_TAG_WEBVIEW);
}
} catch (MissingWebViewPackageException e) {
// If the package doesn't exist,then try loading the null WebView instead.
// If that succeeds,then this is a device without WebView support; if it fails then
// swallow the failure,complain that the real WebView is missing and rethrow the
// original exception.
try {
return (Class<WebViewFactoryProvider>) Class.forName(NULL_WEBVIEW_FACTORY);
} catch (ClassNotFoundException e2) {
// Ignore.
}
Log.e(LOGTAG,"Chromium WebView package does not exist",e);
throw new AndroidRuntimeException(e);
}
}

// throws MissingWebViewPackageException
private static Class<WebViewFactoryProvider> getChromiumProviderClass()
throws ClassNotFoundException {
Application initialApplication = AppGlobals.getInitialApplication();
try {
// Construct a package context to load the Java code into the current app.
Context webViewContext = initialApplication.createPackageContext(
sPackageInfo.packageName,Context.CONTEXT_INCLUDE_CODE | Context.CONTEXT_IGNORE_SECURITY);
initialApplication.getAssets().addAssetPath(
webViewContext.getApplicationInfo().sourceDir);
ClassLoader clazzLoader = webViewContext.getClassLoader();
Trace.traceBegin(Trace.TRACE_TAG_WEBVIEW,"Class.forName()");
try {
return (Class<WebViewFactoryProvider>) Class.forName(CHROMIUM_WEBVIEW_FACTORY,true,clazzLoader);
} finally {
Trace.traceEnd(Trace.TRACE_TAG_WEBVIEW);
}
} catch (PackageManager.NameNotFoundException e) {
throw new MissingWebViewPackageException(e);
}
}

private static final String CHROMIUM_WEBVIEW_FACTORY =
"com.android.webview.chromium.WebViewChromiumFactoryProvider";

@Override
public WebViewProvider createWebView(WebView webView,WebView.PrivateAccess privateAccess) {
WebViewChromium wvc = new WebViewChromium(this,webView,privateAccess);
synchronized (mLock) {
if (mWebViewsToStart != null) {
mWebViewsToStart.add(new WeakReference<WebViewChromium>(wvc));
}
}
ResourceProvider.registerResources(webView.getContext());
return wvc;
}

@Override
public WebSettings getSettings() {
return mWebSettings;
}

@Override
// BUG=6790250 |javaScriptInterfaces| was only ever used by the obsolete DumpRenderTree
// so is ignored. TODO: remove it from WebViewProvider.
public void init(final Map<String,final boolean privateBrowsing) {
if (privateBrowsing) {
mFactory.startYourEngines(true);
final String msg = "Private browsing is not supported in WebView.";
if (mAppTargetSdkVersion >= Build.VERSION_CODES.KITKAT) {
throw new IllegalArgumentException(msg);
} else {
Log.w(TAG,msg);
TextView warningLabel = new TextView(mWebView.getContext());
warningLabel.setText(mWebView.getContext().getString(
com.android.internal.R.string.webviewchromium_private_browsing_warning));
mWebView.addView(warningLabel);
}
}
// We will defer real initialization until we know which thread to do it on,unless:
// - we are on the main thread already (common case),// - the app is targeting >= JB MR2,in which case checkThread enforces that all usage
// comes from a single thread. (Note in JB MR2 this exception was in WebView.java).
if (mAppTargetSdkVersion >= Build.VERSION_CODES.JELLY_BEAN_MR2) {
mFactory.startYourEngines(false);
checkThread();
} else if (!mFactory.hasStarted()) {
if (Looper.myLooper() == Looper.getMainLooper()) {
mFactory.startYourEngines(true);
}
}
final boolean isAccessFromFileURLsGrantedByDefault =
mAppTargetSdkVersion < Build.VERSION_CODES.JELLY_BEAN;
final boolean areLegacyQuirksEnabled =
mAppTargetSdkVersion < Build.VERSION_CODES.KITKAT;
mContentsClientAdapter = new WebViewContentsClientAdapter(mWebView);
mWebSettings = new ContentSettingsAdapter(new AwSettings(
mWebView.getContext(),isAccessFromFileURLsGrantedByDefault,areLegacyQuirksEnabled));
mRunQueue.addTask(new Runnable() {
@Override
public void run() {
initForReal();
if (privateBrowsing) {
// Intentionally irreversibly disable the webview instance,so that private
// user data cannot leak through misuse of a non-privateBrowing WebView
// instance. Can't just null out mAwContents as we never null-check it
// before use.
destroy();
}
}
});
}

@Override
public void setMediaPlaybackRequiresUserGesture(boolean require) {
mAwSettings.setMediaPlaybackRequiresUserGesture(require);
}

public ContentSettingsAdapter(AwSettings awSettings) {
mAwSettings = awSettings;
}

mWebSettings = new ContentSettingsAdapter(new AwSettings(
mWebView.getContext(),areLegacyQuirksEnabled));

/**
* See {@link android.webkit.WebSettings#setMediaPlaybackRequiresUserGesture}.
*/
public void setMediaPlaybackRequiresUserGesture(boolean require) {
synchronized (mAwSettingsLock) {
if (mMediaPlaybackRequiresUserGesture != require) {
mMediaPlaybackRequiresUserGesture = require;
mEventHandler.updateWebkitPreferencesLocked();
}
}
}

@CalledByNative
private boolean getMediaPlaybackRequiresUserGestureLocked() {
return mMediaPlaybackRequiresUserGesture;
}

web_prefs->user_gesture_required_for_media_playback =
Java_AwSettings_getMediaPlaybackRequiresUserGestureLocked(env,obj);