Android WebView not loading second page from cache

I have an Android app that simply houses a website. I would like the app to cache the pages of the website for offline use.

I'm doing a simple test to see if the cache is working but unfortunately it is failing to load a page i have previously loaded in online mode, when offline. To make things clearer i load the following 2 pages when in online mode.

webView.loadUrl("http://www.bmimobile.co.uk/why-bmi.php", getHeaders());
webView.loadUrl("http://www.bmimobile.co.uk/", getHeaders());

I am hoping that the "why-bmi.php" page is loaded into the cache as well as the subsequent page http://www.bmimobile.co.uk/. The latter page has a link on it which refers to the first page. If i then come out of the app and turn the network adapter off then go back into the app the "http://www.bmimobile.co.uk/" page DOES display but when i click the "why-bmi" link that page DOES NOT display. I short toast message displays saying "error loading page".

Can anyone tell me why the webview is not caching loaded page for later offline use?

Here's the main activity and i've extended the Application object defining the appcachepath.

Thanks in advance

Matt

package uk.bmi.mobile;

import java.io.File;
import java.util.HashMap;
import java.util.Map;
import android.app.Activity;
import android.content.Context;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.Bundle;
import android.util.Log;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;



public class MainActivity extends Activity {


    private WebView webView;
    private static final String TAG = MainActivity.class.getSimpleName();
    ApplicationExt bmiAppObj;


    //instruct server to set it's headers to make resources cachable
    private Map<String, String> getHeaders() {
        Map<String, String> headers = new HashMap<String, String>();
        headers.put("IS_ALEX_APP", "1");
        return headers;
    }


    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Log.e(TAG, "in onCreate in mainactivity");



    }      //end of oncreate


    private boolean isNetworkAvailable() {
        ConnectivityManager connectivityManager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo activeNetworkInfo = connectivityManager.getActiveNetworkInfo();
        return activeNetworkInfo != null;
    }



    @Override
    protected void onResume() {
        super.onResume();

        Log.e(TAG, "in onResume in mainactivity");
        webView = (WebView)findViewById(R.id.webView1);
        bmiAppObj = (ApplicationExt)getApplication();


        if(isNetworkAvailable() == true){

            webView.getSettings().setSupportZoom(true);
            webView.getSettings().setBuiltInZoomControls(true);
            webView.setScrollBarStyle(WebView.SCROLLBARS_OUTSIDE_OVERLAY);
            webView.setScrollbarFadingEnabled(true);
            webView.getSettings().setLoadsImagesAutomatically(true);
            webView.getSettings().setDomStorageEnabled(true);
            webView.getSettings().setAppCacheEnabled(true);
            // Set cache size to 8 mb by default. should be more than enough
            webView.getSettings().setAppCacheMaxSize(1024*1024*8);
            // This next one is crazy. It's the DEFAULT location for your app's cache
            // But it didn't work for me without this line.
            // UPDATE: no hardcoded path. Thanks to Kevin Hawkins
            String appCachePath = getApplicationContext().getCacheDir().getAbsolutePath();
            Log.e(TAG, "appCachePath = " + appCachePath);
            webView.getSettings().setAppCachePath(appCachePath);
            webView.getSettings().setAllowFileAccess(true);

            webView.getSettings().setJavaScriptEnabled(true);

            // Load the URLs inside the WebView, not in the external web browser
            webView.setWebViewClient(new WebViewClient());  
            webView.getSettings().setCacheMode(WebSettings.LOAD_DEFAULT);


            webView.loadUrl("http://www.bmimobile.co.uk/why-bmi.php", getHeaders());
            webView.loadUrl("http://www.bmimobile.co.uk/", getHeaders());


            }else{

                webView.getSettings().setSupportZoom(true);
                webView.getSettings().setBuiltInZoomControls(true);
                webView.setScrollBarStyle(WebView.SCROLLBARS_OUTSIDE_OVERLAY);
                webView.setScrollbarFadingEnabled(true);
                webView.getSettings().setLoadsImagesAutomatically(true);
                webView.getSettings().setDomStorageEnabled(true);
                webView.getSettings().setAppCacheEnabled(true);
                // Set cache size to 8 mb by default. should be more than enough
                webView.getSettings().setAppCacheMaxSize(1024*1024*8);
                // This next one is crazy. It's the DEFAULT location for your app's cache
                // But it didn't work for me without this line.
                // UPDATE: no hardcoded path. Thanks to Kevin Hawkins
                String appCachePath = getApplicationContext().getCacheDir().getAbsolutePath();
                Log.e(TAG, "appCachePath = " + appCachePath);
                webView.getSettings().setAppCachePath(appCachePath);
                webView.getSettings().setAllowFileAccess(true);

                webView.getSettings().setJavaScriptEnabled(true);



                // Load the URLs inside the WebView, not in the external web browser
                webView.setWebViewClient(new WebViewClient());  



                webView.getSettings().setCacheMode(WebSettings.LOAD_CACHE_ONLY);

                webView.loadUrl("http://www.bmimobile.co.uk/", getHeaders());


            }


    }






    @Override
    public File getCacheDir()
    {
        // NOTE: this method is used in Android 2.1
        Log.e(TAG, "getcachedir");
        return getApplicationContext().getCacheDir();
    }

    @Override
    protected void onSaveInstanceState(Bundle outState)
    {
        super.onSaveInstanceState(outState);

        // Save the state of the WebView
        webView.saveState(outState);
    }

    @Override
    protected void onRestoreInstanceState(Bundle savedInstanceState)
    {
        super.onRestoreInstanceState(savedInstanceState);

        // Restore the state of the WebView
        webView.restoreState(savedInstanceState);
    }



}//end of mainActivity

package uk.bmi.mobile;

import java.io.File;

import android.app.Application;
import android.os.Environment;
import android.util.Log;

public class ApplicationExt extends Application
{
    private static final String TAG = ApplicationExt.class.getSimpleName();
    // NOTE: the content of this path will be deleted
    //       when the application is uninstalled (Android 2.2 and higher)
    protected File extStorageAppBasePath;

    protected File extStorageAppCachePath;

    Webservice webservice;
    BmiDB bmiDb;

    @Override
    public void onCreate()
    {
        super.onCreate();
         Log.e(TAG, "inside appext");

         webservice = new Webservice(this);
         bmiDb = new BmiDB(this);
        // Check if the external storage is writeable
        if (Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState()))
        {

            // Retrieve the base path for the application in the external storage
            File externalStorageDir = Environment.getExternalStorageDirectory();

            if (externalStorageDir != null)
            {
                // {SD_PATH}/Android/data/com.devahead.androidwebviewcacheonsd
                extStorageAppBasePath = new File(externalStorageDir.getAbsolutePath() +
                    File.separator + "Android" + File.separator + "data" +
                    File.separator + getPackageName());
            }

            if (extStorageAppBasePath != null)
            {
                // {SD_PATH}/Android/data/com.devahead.androidwebviewcacheonsd/cache
                extStorageAppCachePath = new File(extStorageAppBasePath.getAbsolutePath() +
                    File.separator + "cache");

                boolean isCachePathAvailable = true;

                if (!extStorageAppCachePath.exists())
                {
                    // Create the cache path on the external storage
                    isCachePathAvailable = extStorageAppCachePath.mkdirs();
                }

                if (!isCachePathAvailable)
                {
                    // Unable to create the cache path
                    extStorageAppCachePath = null;
                }
            }
        }
    }//end of onCreate

    @Override
    public File getCacheDir()
    {
        // NOTE: this method is used in Android 2.2 and higher

        if (extStorageAppCachePath != null)
        {
            // Use the external storage for the cache
            Log.e(TAG, "extStorageAppCachePath = " + extStorageAppCachePath);
            return extStorageAppCachePath;
        }
        else
        {
            // /data/data/com.devahead.androidwebviewcacheonsd/cache
            return super.getCacheDir();
        }
    }
}

.This is the logging when the app is first loaded in online mode

02-16 08:38:52.744: I/NONPRIME(8871): <CallBackProxy> Send to WebViewClient.
02-16 08:38:56.314: D/skia(8871): ----- started: [1 325] http://www.bmimobile.co.uk/images/mobile/bg-index.png
02-16 08:38:56.499: D/skia(8871): ----- started: [1 64] http://www.bmimobile.co.uk/CubeCore/modules/cubeMobile/images/bg-black-bar.png
02-16 08:38:56.509: D/skia(8871): ----- started: [26 20] http://www.bmimobile.co.uk/images/mobile/home-icon.png
02-16 08:38:56.529: D/skia(8871): ----- started: [275 189] http://www.bmimobile.co.uk/images/mobile/home-img.png
02-16 08:38:56.549: D/skia(8871): ----- started: [320 450] http://www.bmimobile.co.uk/images/mobile/welcome/bg-welcome.jpg
02-16 08:38:56.554: D/skia(8871): ----- started: [270 38] http://www.bmimobile.co.uk/images/mobile/welcome/next.png
02-16 08:38:56.584: D/skia(8871): ----- started: [16 17] http://www.bmimobile.co.uk/images/mobile/why.png
02-16 08:38:56.584: D/skia(8871): ----- started: [18 17] http://www.bmimobile.co.uk/images/mobile/services.png
02-16 08:38:56.584: D/skia(8871): ----- started: [20 15] http://www.bmimobile.co.uk/images/mobile/visit.png
02-16 08:38:56.589: D/skia(8871): ----- started: [20 15] http://www.bmimobile.co.uk/images/mobile/consultants.png
02-16 08:38:56.589: D/skia(8871): ----- started: [13 19] http://www.bmimobile.co.uk/images/mobile/contact.png

This is the logging when i've come out of the app turned off the network adapter then gone back into app in offline mode.

02-16 08:41:37.799: E/MainActivity(8871): in onResume in mainactivity
02-16 08:41:37.804: E/ApplicationExt(8871): extStorageAppCachePath = /storage/sdcard0/Android/data/uk.bmi.mobile/cache
02-16 08:41:37.804: E/MainActivity(8871): appCachePath = /storage/sdcard0/Android/data/uk.bmi.mobile/cache
02-16 08:41:37.834: W/dalvikvm(8871): disableGcForExternalAlloc: false

[edit1] Actually on closer inspection of the logging, it seems to have changed when loaded in online mode. below is the logcat in omline mode. There seems to be a problem with the cache storage.

02-19 15:16:10.497: E/ApplicationExt(5467): inside appext
02-19 15:16:10.687: E/ApplicationExt(5467): extStorageAppCachePath = /storage/sdcard0/Android/data/uk.bmi.mobile/cache
02-19 15:16:10.722: E/MainActivity(5467): in onCreate in mainactivity
02-19 15:16:10.727: E/MainActivity(5467): in onResume in mainactivity
02-19 15:16:10.737: E/ApplicationExt(5467): extStorageAppCachePath = /storage/sdcard0/Android/data/uk.bmi.mobile/cache
02-19 15:16:10.737: E/MainActivity(5467): appCachePath = /storage/sdcard0/Android/data/uk.bmi.mobile/cache
02-19 15:16:10.792: E/(5467): file /data/data/com.nvidia.NvCPLSvc/files/driverlist.txt: not found!
02-19 15:16:10.792: I/(5467): Attempting to load EGL implementation /system/lib//egl/libEGL_tegra_impl
02-19 15:16:10.807: I/(5467): Loaded EGL implementation /system/lib//egl/libEGL_tegra_impl
02-19 15:16:10.842: I/(5467): Loading GLESv2 implementation /system/lib//egl/libGLESv2_tegra_impl
02-19 15:16:10.882: E/SQLiteLog(5467): (1) no such table: CacheGroups
02-19 15:16:10.882: D/WebKit(5467): ERROR: 
02-19 15:16:10.882: D/WebKit(5467): Application Cache Storage: failed to execute statement "DELETE FROM CacheGroups" error "no such table: CacheGroups"
02-19 15:16:10.882: D/WebKit(5467): external/webkit/Source/WebCore/loader/appcache/ApplicationCacheStorage.cpp(558) : bool WebCore::ApplicationCacheStorage::executeSQLCommand(const WTF::String&)
02-19 15:16:10.882: E/SQLiteLog(5467): (1) no such table: Caches
02-19 15:16:10.882: D/WebKit(5467): ERROR: 
02-19 15:16:10.882: D/WebKit(5467): Application Cache Storage: failed to execute statement "DELETE FROM Caches" error "no such table: Caches"
02-19 15:16:10.882: D/WebKit(5467): external/webkit/Source/WebCore/loader/appcache/ApplicationCacheStorage.cpp(558) : bool WebCore::ApplicationCacheStorage::executeSQLCommand(const WTF::String&)
02-19 15:16:10.882: E/SQLiteLog(5467): (1) no such table: Origins
02-19 15:16:10.882: D/WebKit(5467): ERROR: 
02-19 15:16:10.882: D/WebKit(5467): Application Cache Storage: failed to execute statement "DELETE FROM Origins" error "no such table: Origins"
02-19 15:16:10.882: D/WebKit(5467): external/webkit/Source/WebCore/loader/appcache/ApplicationCacheStorage.cpp(558) : bool WebCore::ApplicationCacheStorage::executeSQLCommand(const WTF::String&)
02-19 15:16:10.882: E/SQLiteLog(5467): (1) no such table: DeletedCacheResources
02-19 15:16:10.992: E/ApplicationExt(5467): extStorageAppCachePath = /storage/sdcard0/Android/data/uk.bmi.mobile/cache
02-19 15:16:11.022: W/dalvikvm(5467): disableGcForExternalAlloc: false
02-19 15:16:13.787: I/NONPRIME(5467): <CallBackProxy> Send to WebViewClient.
02-19 15:16:21.427: D/skia(5467): ----- started: [1 325] http://www.bmimobile.co.uk/images/mobile/bg-index.png
02-19 15:16:21.517: D/skia(5467): ----- started: [1 64] http://www.bmimobile.co.uk/CubeCore/modules/cubeMobile/images/bg-black-bar.png
02-19 15:16:21.542: D/skia(5467): ----- started: [26 20] http://www.bmimobile.co.uk/images/mobile/home-icon.png
02-19 15:16:21.577: D/skia(5467): ----- started: [275 189] http://www.bmimobile.co.uk/images/mobile/home-img.png
02-19 15:16:21.597: D/skia(5467): ----- started: [270 38] http://www.bmimobile.co.uk/images/mobile/welcome/next.png
02-19 15:16:21.677: D/skia(5467): ----- started: [16 17] http://www.bmimobile.co.uk/images/mobile/why.png
02-19 15:16:21.677: D/skia(5467): ----- started: [20 15] http://www.bmimobile.co.uk/images/mobile/visit.png
02-19 15:16:21.677: D/skia(5467): ----- started: [18 17] http://www.bmimobile.co.uk/images/mobile/services.png
02-19 15:16:21.687: D/skia(5467): ----- started: [20 15] http://www.bmimobile.co.uk/images/mobile/consultants.png
02-19 15:16:21.687: D/skia(5467): ----- started: [13 19] http://www.bmimobile.co.uk/images/mobile/contact.png
02-19 15:16:21.692: D/skia(5467): ----- started: [320 450] http://www.bmimobile.co.uk/images/mobile/welcome/bg-welcome.jpg

[notes] if i click on the why-bmi button when in online mode then come out of the app, turn the adapter off then click the why-bmi button again then it shows the "error loading page" message.

If i however change to the following urls, my SO page is displayed. If i click the link to my bounty page(this page), then go offline, the SO page is display as you would expect but if you click the bounty link in offline mode then it DOES display. so there are differences between the SO site and the bmi site.

if(isNetworkAvailable() == true){

            webView.getSettings().setSupportZoom(true);
            webView.getSettings().setBuiltInZoomControls(true);
            webView.setScrollBarStyle(WebView.SCROLLBARS_OUTSIDE_OVERLAY);
            webView.setScrollbarFadingEnabled(true);
            webView.getSettings().setLoadsImagesAutomatically(true);
            webView.getSettings().setDomStorageEnabled(true);
            webView.getSettings().setAppCacheEnabled(true);
            // Set cache size to 8 mb by default. should be more than enough
            webView.getSettings().setAppCacheMaxSize(1024*1024*8);
            // This next one is crazy. It's the DEFAULT location for your app's cache
            // But it didn't work for me without this line.
            // UPDATE: no hardcoded path. Thanks to Kevin Hawkins
            String appCachePath = getApplicationContext().getCacheDir().getAbsolutePath();
            Log.e(TAG, "appCachePath = " + appCachePath);
            webView.getSettings().setAppCachePath(appCachePath);
            webView.getSettings().setAllowFileAccess(true);

            webView.getSettings().setJavaScriptEnabled(true);

            // Load the URLs inside the WebView, not in the external web browser
            webView.setWebViewClient(new WebViewClient());  
            webView.getSettings().setCacheMode(WebSettings.LOAD_DEFAULT);


            //webView.loadUrl("http://www.bmimobile.co.uk/why-bmi.php", getHeaders());
            //webView.loadUrl("http://www.bmimobile.co.uk/", getHeaders());

            webView.loadUrl("http://stackoverflow.com/users/532462/turtleboy?tab=bounties");
            webView.loadUrl("http://stackoverflow.com/users/532462/turtleboy");
            }else{

                webView.getSettings().setSupportZoom(true);
                webView.getSettings().setBuiltInZoomControls(true);
                webView.setScrollBarStyle(WebView.SCROLLBARS_OUTSIDE_OVERLAY);
                webView.setScrollbarFadingEnabled(true);
                webView.getSettings().setLoadsImagesAutomatically(true);
                webView.getSettings().setDomStorageEnabled(true);
                webView.getSettings().setAppCacheEnabled(true);
                // Set cache size to 8 mb by default. should be more than enough
                webView.getSettings().setAppCacheMaxSize(1024*1024*8);
                // This next one is crazy. It's the DEFAULT location for your app's cache
                // But it didn't work for me without this line.
                // UPDATE: no hardcoded path. Thanks to Kevin Hawkins
                String appCachePath = getApplicationContext().getCacheDir().getAbsolutePath();
                Log.e(TAG, "appCachePath = " + appCachePath);
                webView.getSettings().setAppCachePath(appCachePath);
                webView.getSettings().setAllowFileAccess(true);

                webView.getSettings().setJavaScriptEnabled(true);



                // Load the URLs inside the WebView, not in the external web browser
                webView.setWebViewClient(new WebViewClient());  



                webView.getSettings().setCacheMode(WebSettings.LOAD_CACHE_ONLY);

               // webView.loadUrl("http://www.bmimobile.co.uk/", getHeaders());
                webView.loadUrl("http://stackoverflow.com/users/532462/turtleboy");


            }


    }

[edit2]

    <?xml version="1.0" encoding="utf-8"?>
    <manifest xmlns:android="http://schemas.android.com/apk/res/android"
        package="uk.bmi.mobile"
        android:versionCode="5"
        android:versionName="1.0.4" >

        <!-- GCM requires Android SDK version 2.2 (API level <img src="http://www.androidhive.info/wp-includes/images/smilies/icon_cool.gif" alt="8)" class="wp-smiley"> or above. -->
        <uses-sdk
            android:minSdkVersion="8"
            android:targetSdkVersion="16" />

        <!-- GCM connects to Internet Services. -->
        <uses-permission android:name="android.permission.INTERNET" />

        <!-- GCM requires a Google account. -->
        <uses-permission android:name="android.permission.GET_ACCOUNTS" />

        <!-- Keeps the processor from sleeping when a message is received. -->
        <uses-permission android:name="android.permission.WAKE_LOCK" />

        <!-- Creates a custom permission so only this app can receive its messages. -->
        <permission
            android:name="uk.bmi.mobile.permission.C2D_MESSAGE"
            android:protectionLevel="signature" />

        <uses-permission android:name="uk.bmi.mobile.permission.C2D_MESSAGE" />

        <!-- This app has permission to register and receive data message. -->
        <uses-permission android:name="com.google.android.c2dm.permission.RECEIVE" />

        <!-- Network State Permissions to detect Internet status -->
        <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

        <!-- Permission to vibrate -->
        <uses-permission android:name="android.permission.VIBRATE" />

    <uses-permission android:name="android.permisson.ACCESS_WIFI_STATE"/>
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>

        <!-- Main activity. -->
        <application
            android:icon="@drawable/bmi_icon"
            android:label="@string/app_name"
            android:name="uk.bmi.mobile.ApplicationExt" >
            <!-- Register Activity -->
            <activity
                android:name=".RegisterActivity"
                android:label="@string/app_name" >
                <intent-filter>
                    <action android:name="android.intent.action.MAIN" />

                    <category android:name="android.intent.category.LAUNCHER" />
                </intent-filter>
            </activity>

            <!-- Main Activity -->
            <activity
                android:name="uk.bmi.mobile.MainActivity"
                android:configChanges="orientation|keyboardHidden"
                android:label="@string/app_name"
                 android:screenOrientation="portrait" >
            </activity>

            <receiver
                android:name="com.google.android.gcm.GCMBroadcastReceiver"
                android:permission="com.google.android.c2dm.permission.SEND" >
                <intent-filter>

                    <!-- Receives the actual messages. -->
                    <action android:name="com.google.android.c2dm.intent.RECEIVE" />
                    <!-- Receives the registration id. -->
                    <action android:name="com.google.android.c2dm.intent.REGISTRATION" />

                    <category android:name="uk.bmi.mobile" />
                </intent-filter>
            </receiver>

            <service android:name="uk.bmi.mobile.GCMIntentService" />
        </application>

    </manifest>

标签： android caching webview

5条回答

SAY GOODBYE

2楼-- · 2019-04-05 12:53

There are occasions that a WebView cannot be cached natively. If the page header contains the following fields, the WebView will not be able to cache the contents from that page.

Cache-Control: no-store, no-cache
Pragma: no-cache

In this case, youwill have to modify the page property on the server to solve the caching problem.

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ら.Afraid

3楼-- · 2019-04-05 12:56

This is not the exact answer to your question, as you are asking about webview cache. But, it can achieve the same result.

// saving page from web to file 
File file = new File(this.getExternalFilesDir(null), "fileName.html");
FileUtils.copyURLToFile(new URL("http://www.bmimobile.co.uk/why-bmi.php"), file);


// loading saved file in webview
webview.loadUrl("file://" + file.getPath());

This is a more flexible approach, as you have control over loading, saving, and much more.

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【Aperson】

4楼-- · 2019-04-05 13:03

Perhaps a solution to your problem would be to make an HTTP get request alongside your webview loading.

The result of the get request could be stored in a string persistenly in sharedpreferences, and it will be the HTML that your php renders.

in your android lifecycle, you can determine if the app is offline, and if it is offline you can load the last saved version of the site from string

webview.loadData(yourSavedString, "text/html", "UTF-8");

although if there are images you will have to make extra considerations, but if the images are not dynamic you can store them in your app's asset folder and replace the URL in the saved string with the asset locations.

although it does not solve why your webview is not caching, it will accomplish the same end goal or viewing the page offline

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一纸荒年 Trace。

5楼-- · 2019-04-05 13:11

Another very flexible and powerful option can be using HTML5 to manage the caching in your app..

Have a look at http://diveintohtml5.info/offline.html

You can simply enable caching in your app and manage the caching from the web end itself.

Best Regards

Aman Gautam

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欢心

6楼-- · 2019-04-05 13:17

Its little Silly that this works. There is a redirect in URL from

http://www.bmimobile.co.uk/ to http://www.bmimobile.co.uk/index.php

You Should try

webView.loadUrl("http://www.bmimobile.co.uk/why-bmi.php", getHeaders()); webView.loadUrl("http://www.bmimobile.co.uk/index.php", getHeaders());

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Android WebView not loading second page from cache

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