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      1 /*
      2  * Copyright (C) 2012 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package android.webkit;
     18 
     19 import android.os.Build;
     20 import android.os.StrictMode;
     21 import android.os.SystemProperties;
     22 import android.util.AndroidRuntimeException;
     23 import android.util.Log;
     24 
     25 /**
     26  * Top level factory, used creating all the main WebView implementation classes.
     27  *
     28  * @hide
     29  */
     30 public final class WebViewFactory {
     31 
     32     private static final String CHROMIUM_WEBVIEW_FACTORY =
     33             "com.android.webview.chromium.WebViewChromiumFactoryProvider";
     34 
     35     private static final String LOGTAG = "WebViewFactory";
     36 
     37     private static final boolean DEBUG = false;
     38 
     39     private static class Preloader {
     40         static WebViewFactoryProvider sPreloadedProvider;
     41         static {
     42             try {
     43                 sPreloadedProvider = getFactoryClass().newInstance();
     44             } catch (Exception e) {
     45                 Log.w(LOGTAG, "error preloading provider", e);
     46             }
     47         }
     48     }
     49 
     50     // Cache the factory both for efficiency, and ensure any one process gets all webviews from the
     51     // same provider.
     52     private static WebViewFactoryProvider sProviderInstance;
     53     private static final Object sProviderLock = new Object();
     54 
     55     public static boolean isExperimentalWebViewAvailable() {
     56         // TODO: Remove callers of this method then remove it.
     57         return false;  // Hide the toggle in Developer Settings.
     58     }
     59 
     60     /** @hide */
     61     public static void setUseExperimentalWebView(boolean enable) {
     62         // TODO: Remove callers of this method then remove it.
     63     }
     64 
     65     /** @hide */
     66     public static boolean useExperimentalWebView() {
     67         // TODO: Remove callers of this method then remove it.
     68         return true;
     69     }
     70 
     71     /** @hide */
     72     public static boolean isUseExperimentalWebViewSet() {
     73         // TODO: Remove callers of this method then remove it.
     74         return false;  // User has not modifed Developer Settings
     75     }
     76 
     77     static WebViewFactoryProvider getProvider() {
     78         synchronized (sProviderLock) {
     79             // For now the main purpose of this function (and the factory abstraction) is to keep
     80             // us honest and minimize usage of WebView internals when binding the proxy.
     81             if (sProviderInstance != null) return sProviderInstance;
     82 
     83             Class<WebViewFactoryProvider> providerClass;
     84             try {
     85                 providerClass = getFactoryClass();
     86             } catch (ClassNotFoundException e) {
     87                 Log.e(LOGTAG, "error loading provider", e);
     88                 throw new AndroidRuntimeException(e);
     89             }
     90 
     91             // This implicitly loads Preloader even if it wasn't preloaded at boot.
     92             if (Preloader.sPreloadedProvider != null &&
     93                 Preloader.sPreloadedProvider.getClass() == providerClass) {
     94                 sProviderInstance = Preloader.sPreloadedProvider;
     95                 if (DEBUG) Log.v(LOGTAG, "Using preloaded provider: " + sProviderInstance);
     96                 return sProviderInstance;
     97             }
     98 
     99             // The preloaded provider isn't the one we wanted; construct our own.
    100             StrictMode.ThreadPolicy oldPolicy = StrictMode.allowThreadDiskReads();
    101             try {
    102                 sProviderInstance = providerClass.newInstance();
    103                 if (DEBUG) Log.v(LOGTAG, "Loaded provider: " + sProviderInstance);
    104                 return sProviderInstance;
    105             } catch (Exception e) {
    106                 Log.e(LOGTAG, "error instantiating provider", e);
    107                 throw new AndroidRuntimeException(e);
    108             } finally {
    109                 StrictMode.setThreadPolicy(oldPolicy);
    110             }
    111         }
    112     }
    113 
    114     private static Class<WebViewFactoryProvider> getFactoryClass() throws ClassNotFoundException {
    115         return (Class<WebViewFactoryProvider>) Class.forName(CHROMIUM_WEBVIEW_FACTORY);
    116     }
    117 }
    118