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    <p>I get dozens of crash log caused by this exception from my app (which depends on webview heavily), involved ROM version are 4.0.4 and 4.0.3.</p> <p>It seems that there is no normal way to fix it, so i tried following hacking approach.</p> <p>code snipet on 4.0.4:</p> <pre><code>private static Handler sWebCoreHandler; // Class for providing Handler creation inside the WebCore thread. private static class WebCoreThread implements Runnable { // Message id for initializing a new WebViewCore. private static final int INITIALIZE = 0; private static final int REDUCE_PRIORITY = 1; private static final int RESUME_PRIORITY = 2; public void run() { Looper.prepare(); Assert.assertNull(sWebCoreHandler); synchronized (WebViewCore.class) { sWebCoreHandler = new Handler() { @Override public void handleMessage(Message msg) { // ... // Process.setPriority(...) } }; // ... } // ... } } </code></pre> <p>I think this exception is thrown from sWebCoreHandler.handleMessage(), if we can wrap try/catch on handleMessage(), the problem could be fixed.</p> <p>Handler class has four members:</p> <pre><code>final MessageQueue mQueue; final Looper mLooper; final Callback mCallback; IMessenger mMessenger; </code></pre> <p>mQueue is set as mLooper.mQueue, mCallback is null in sWebCoreHandler, so we just need to set mLooper and mMessenger with values in sWebCoreHandler.</p> <pre><code>static Handler sProxyHandler = null; static void tryTweakWebCoreHandler() { // 4.0.3/4.0.4 rom if (Build.VERSION.SDK_INT == Build.VERSION_CODES.ICE_CREAM_SANDWICH_MR1) { tweakWebCoreHandle(); } } static private void tweakWebCoreHandle() { if (sProxyHandler != null) return; try { Field f = Class.forName("android.webkit.WebViewCore").getDeclaredField("sWebCoreHandler"); f.setAccessible(true); Object h = f.get(null); Object mMessenger = null; Method m = Handler.class.getDeclaredMethod("getIMessenger", (Class&lt;?&gt;[])null); m.setAccessible(true); mMessenger = m.invoke(h, (Object[])null); sProxyHandler = new WebCoreProxyHandler((Handler)h); if (mMessenger != null) { Field f1 = Handler.class.getDeclaredField("mMessenger"); f1.setAccessible(true); f1.set(sProxyHandler, mMessenger); } f.set(null, sProxyHandler); // Log.w(TAG, "sWebCoreHandler: " + h); } catch (Throwable e) { Log.w(TAG, "exception: " + e); } if (sProxyHandler == null) sProxyHandler = new Handler(); } static class WebCoreProxyHandler extends Handler { final Handler handler; public WebCoreProxyHandler(Handler handler) { super(handler.getLooper()); this.handler = handler; } public void handleMessage(Message msg) { // Log.w("WebCoreProxyHandler", "handle msg: " + msg.what); try { handler.handleMessage(msg); } catch (Throwable tr) { Log.w("WebCoreProxyHandler", "exception: " + tr); } } } </code></pre> <p>Remain problem is when to invoke tryTweakWebCoreHandler(). I tried to invoke it after a WebView instance is created and tested on some devices, WebCoreProxyHandler.handleMessage() can be called.</p> <p>Note: i just made some simple test, i'm not sure this problem is resolved as the origin exception can not be reproduced reliably.</p> <p>If you decide to try this approach, please do enough test.</p>
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    1. POAndroid WebView No permission to modify given thread, which permission should I declare？
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