记录 Android(安卓)WebView 开发过程的坑和解决方法

这篇主要总结 WebView 相关的疑难 bug，由于 Android 版本严重碎片化，在使用 WebView 的时候也会遇到各种个样的坑，特别是 4.4 之后更换了 WebView 内核，4.2 以下有部分漏洞，所以想把经历过的 WebView 这些坑记录下来，仅供参考。

1、

java.lang.NullPointerException    at android.webkit.AccessibilityInjector$TextToSpeechWrapper$1.onInit(AccessibilityInjector.java:753)    at android.speech.tts.TextToSpeech.dispatchOnInit(TextToSpeech.java:640)    at android.speech.tts.TextToSpeech.initTts(TextToSpeech.java:619)    at android.speech.tts.TextToSpeech.(TextToSpeech.java:553)    at android.webkit.AccessibilityInjector$TextToSpeechWrapper.(AccessibilityInjector.java:676)    at android.webkit.AccessibilityInjector.addTtsApis(AccessibilityInjector.java:480)    at android.webkit.AccessibilityInjector.addAccessibilityApisIfNecessary(AccessibilityInjector.java:168)    at android.webkit.AccessibilityInjector.onPageStarted(AccessibilityInjector.java:340)    at android.webkit.WebViewClassic.onPageStarted(WebViewClassic.java:4480)    at android.webkit.CallbackProxy.handleMessage(CallbackProxy.java:366)    at android.os.Handler.dispatchMessage(Handler.java:107)    at android.os.Looper.loop(Looper.java:194)    at android.app.ActivityThread.main(ActivityThread.java:5407)    at java.lang.reflect.Method.invokeNative(Native Method)    at java.lang.reflect.Method.invoke(Method.java:525)    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)    at dalvik.system.NativeStart.main(Native Method)

此问题在4.2.1和4.2.2比较集中，关闭辅助功能，google 下很多结果都是一样的。

修复方法：在初始化 WebView 时调用disableAccessibility方法即可。

public static void disableAccessibility(Context context) {        if (Build.VERSION.SDK_INT == 17/*4.2 (Build.VERSION_CODES.JELLY_BEAN_MR1)*/) {            if (context != null) {                try {                    AccessibilityManager am = (AccessibilityManager) context.getSystemService(Context.ACCESSIBILITY_SERVICE);                    if (!am.isEnabled()) {                        //Not need to disable accessibility                        return;                    }                    Method setState = am.getClass().getDeclaredMethod("setState", int.class);                    setState.setAccessible(true);                    setState.invoke(am, 0);/**{@link AccessibilityManager#STATE_FLAG_ACCESSIBILITY_ENABLED}*/                } catch (Exception ignored) {                    ignored.printStackTrace();                }            }        }    }

2、

AndroidRuntimeException: android.content.pm.PackageManager$NameNotFoundException: com.google.android.webview    at android.app.ActivityThread.handleBindApplication(ActivityThread.java:4604)    at android.app.ActivityThread.access$1500(ActivityThread.java:154)    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1389)    at android.os.Handler.dispatchMessage(Handler.java:102)    at android.os.Looper.loop(Looper.java:135)    at android.app.ActivityThread.main(ActivityThread.java:5302)    at java.lang.reflect.Method.invoke(Native Method)    at java.lang.reflect.Method.invoke(Method.java:372)    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:916)    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:711)Caused by: android.util.AndroidRuntimeException: android.content.pm.PackageManager$NameNotFoundException: com.google.android.webview    at android.webkit.WebViewFactory.getFactoryClass(WebViewFactory.java:174)    at android.webkit.WebViewFactory.getProvider(WebViewFactory.java:109)    at android.webkit.WebView.getFactory(WebView.java:2194)    at android.webkit.WebView.ensureProviderCreated(WebView.java:2189)    at android.webkit.WebView.setOverScrollMode(WebView.java:2248)    at android.view.View.(View.java:3588)    at android.view.View.(View.java:3682)    at android.view.ViewGroup.(ViewGroup.java:497)    at android.widget.AbsoluteLayout.(AbsoluteLayout.java:55)    at android.webkit.WebView.(WebView.java:544)    at android.webkit.WebView.(WebView.java:489)    at android.webkit.WebView.(WebView.java:472)    at android.webkit.WebView.(WebView.java:459)    at android.webkit.WebView.(WebView.java:449)

现象：在创建 WebView 时崩溃，跟进栈信息，我们需要在 setOverScrollMode 方法上加异常保护处理

修复方法：

try {    super.setOverScrollMode(mode);} catch (Throwable e) {    e.printStackTrace();}

不过上面捕获的异常范围有点广，在github上找到一个更全面的修复方法

try{    super.setOverScrollMode(mode);} catch(Throwable e){        String messageCause = e.getCause() == null ? e.toString() : e.getCause().toString();String trace = Log.getStackTraceString(e);if (trace.contains("android.content.pm.PackageManager$NameNotFoundException")  || trace.contains("java.lang.RuntimeException: Cannot load WebView")    || trace.contains("android.webkit.WebViewFactory$MissingWebViewPackageException: Failed to load WebView provider: No WebView installed")) {      e.printStackTrace();    }else{      throw e;    }        }

3、

at android.webkit.BrowserFrame.nativeLoadUrl(Native Method)System.err:     at android.webkit.BrowserFrame.loadUrl(BrowserFrame.java:279)System.err:     at android.webkit.WebViewCore.loadUrl(WebViewCore.java:2011)System.err:     at android.webkit.WebViewCore.access$1900(WebViewCore.java:57)System.err:     at android.webkit.WebViewCore$EventHub$1.handleMessage(WebViewCore.java:1303)System.err:     at android.os.Handler.dispatchMessage(Handler.java:99)System.err:     at android.os.Looper.loop(Looper.java:137)System.err:     at android.webkit.WebViewCore$WebCoreThread.run(WebViewCore.java:812)System.err:     at java.lang.Thread.run(Thread.java:856)webcoreglue: *** Uncaught exception returned from Java call!System.err: java.lang.NullPointerExceptionSystem.err:     at android.webkit.WebViewClassic.clearView(WebViewClassic.java:2868)System.err:     at android.webkit.WebViewCore.setupViewport(WebViewCore.java:2497)System.err:     at android.webkit.WebViewCore.updateViewport(WebViewCore.java:2479)System.err:     at android.webkit.BrowserFrame.nativeLoadUrl(Native Method)System.err:     at android.webkit.BrowserFrame.loadUrl(BrowserFrame.java:279)System.err:     at android.webkit.WebViewCore.loadUrl(WebViewCore.java:2011)System.err:     at android.webkit.WebViewCore.access$1900(WebViewCore.java:57)System.err:     at android.webkit.WebViewCore$EventHub$1.handleMessage(WebViewCore.java:1303)System.err:     at android.os.Handler.dispatchMessage(Handler.java:99)System.err:     at android.os.Looper.loop(Looper.java:137)

这个bug是在某些设备上发生的，是在调用webView.destroy() 之前调用了loadurl操作发生的，也不是毕现问题，所以只能跟进源码查看，
在清空 webview destroy 时，调用清理方法，内部可能时机有问题，会出现，WebViewClassic 中 mWebViewCore 对象为null，其内部为handler消息机制。

修复方法：

public void logdUrl(final String url) {    try {        super.loadUrl(url);    } catch (NullPointerException e) {        e.printStackTrace();    }}

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