如果关闭网络适配器,则应从缓存加载webview.这部分不起作用.我已经按照下面的教程并从中获取了一些部分,以便将网站页面保存在SD卡上保存的缓存中.

如果我运行该应用程序,则会显示该网站.如果我然后关闭网络适配器并访问该网站,它将不会显示.我检查了SD卡上的缓存目录,并且部分站点已写入缓存.

为什么网站在离线时不会从缓存中加载？

是否可以将网页保留为缓存,直到说应用程序被卸载或android决定否则？

tutorial

本教程介绍如何在SD卡上创建目录并写入目录.目录确实存在,但在脱机模式下不会从此缓存中恢复webview.

下面是我如何调用显示webview的mainactivity.

Intent i = new Intent(getApplicationContext(),MainActivity.class);
                //i.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
                i.putExtra("name","hardcoded client name");
                i.putExtra("email","hardcoded email");
                startActivity(i);
                finish();

.

这是完整的MainActivity.您可以忽略第一部分,因为这是处理GCM推送通知内容的代码,一切正常.我需要知道为什么webview不会从缓存中加载.

import static com.bmi.bmitestapp.CommonUtilities.DISPLAY_MESSAGE_ACTION;
import static com.bmi.bmitestapp.CommonUtilities.EXTRA_MESSAGE;
import static com.bmi.bmitestapp.CommonUtilities.SENDER_ID;

import java.io.File;

import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.webkit.WebChromeClient;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.TextView;
import android.widget.Toast;
import android.webkit.*;


import com.google.android.gcm.GCMRegistrar;

public class MainActivity extends Activity {
    private static final String TAG = MainActivity.class.getSimpleName();
    // label to display gcm messages
    TextView lblMessage;
    WebView webView;
    // Asyntask
    AsyncTask<Void,Void,Void> mRegisterTask;

    // Alert dialog manager
    AlertDialogManager alert = new AlertDialogManager();

    // Connection detector
    ConnectionDetector cd;

    public static String name;
    public static String email;

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

        Log.e(TAG,"in onCreate in mainactivity");
        cd = new ConnectionDetector(getApplicationContext());

        // Check if Internet present
//        if (!cd.isConnectingToInternet()) {
//            // Internet Connection is not present
//            alert.showAlertDialog(MainActivity.this,//                    "Internet Connection Error",//                    "Please connect to working Internet connection",false);
//            // stop executing code by return
//            return;
//        }

        // Getting name,email from intent
        Intent i = getIntent();

        name = i.getStringExtra("name");
        email = i.getStringExtra("email");     

        // Make sure the device has the proper dependencies.
        GCMRegistrar.checkDevice(this);

        // Make sure the manifest was properly set - comment out this line
        // while developing the app,then uncomment it when it's ready.
        GCMRegistrar.checkManifest(this);

        lblMessage = (TextView) findViewById(R.id.lblMessage);

        registerReceiver(mHandleMessageReceiver,new IntentFilter(
                DISPLAY_MESSAGE_ACTION));

        // Get GCM registration id
        final String regId = GCMRegistrar.getRegistrationId(this);

        // Check if regid already presents
        if (regId.equals("")) {
            // Registration is not present,register now with GCM
            GCMRegistrar.register(this,SENDER_ID);
        } else {
            // Device is already registered on GCM
            if (GCMRegistrar.isRegisteredOnServer(this)) {
                // Skips registration.
                Toast.makeText(getApplicationContext(),"Already registered with GCM",Toast.LENGTH_LONG).show();
            } else {
                // Try to register again,but not in the UI thread.
                // It's also necessary to cancel the thread onDestroy(),// hence the use of AsyncTask instead of a raw thread.
                final Context context = this;
                mRegisterTask = new AsyncTask<Void,Void>() {

                    @Override
                    protected Void doInBackground(Void... params) {
                        // Register on our server
                        // On server creates a new user
                        ServerUtilities.register(context,name,email,regId);
                        return null;
                    }

                    @Override
                    protected void onPostExecute(Void result) {
                        mRegisterTask = null;
                    }

                };
                mRegisterTask.execute(null,null,null);
            }
        }

            webView = (WebView)findViewById(R.id.webView1);
            // Initialize the WebView
            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);

            // 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().setAppCacheEnabled(true);




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

            if (savedInstanceState == null)
                        {



        if(isNetworkAvailable() == true){
            Log.e(TAG,"we have a network connection");
            webView.getSettings().setCacheMode(WebSettings.LOAD_DEFAULT);

            webView.loadUrl("http://bmi.cubecore.co.uk");


        } else {
            Log.e(TAG,"we don't have a network connection");
            webView.getSettings().setCacheMode(WebSettings.LOAD_CACHE_ONLY);

            webView.loadUrl("http://bmi.cubecore.co.uk");
        }


                        } 

    }      //end of oncreate


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


    /**
     * Receiving push messages
     * */
    private final BroadcastReceiver mHandleMessageReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context,Intent intent) {
            String newMessage = intent.getExtras().getString(EXTRA_MESSAGE);
            // Waking up mobile if it is sleeping
            WakeLocker.acquire(getApplicationContext());

            /**
             * Take appropriate action on this message
             * depending upon your app requirement
             * For now i am just displaying it on the screen
             * */

            // Showing received message
            lblMessage.append(newMessage + "\n");
            Toast.makeText(getApplicationContext(),"New Message: " + newMessage,Toast.LENGTH_LONG).show();

            // Releasing wake lock
            WakeLocker.release();
        }
    };

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

        // Clear the cache (this clears the WebViews cache for the entire application)
        //webView.clearCache(false);

        if (mRegisterTask != null) {
            mRegisterTask.cancel(true);
        }
        try {
            unregisterReceiver(mHandleMessageReceiver);
            GCMRegistrar.onDestroy(this);
        } catch (Exception e) {
            Log.e("UnRegister Receiver Error","> " + e.getMessage());
        }



    }



    @Override
    public void onBackPressed() {
        super.onBackPressed();


    }

    @Override
    protected void onResume() {
        super.onResume();
        Log.e(TAG,"in onResume in mainactivity");

    }



    @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);
    }

}

.

这是上面教程中写入sdcard的代码.

package com.bmi.bmitestapp;

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;

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

    @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();
        }
    }
}

我以为我会包括一点点伐木.这是在网络适配器打开的情况下从全新安装进行的日志记录.

01-29 14:13:10.220: D/dalvikvm(16904): Late-enabling CheckJNI
01-29 14:13:10.470: E/ApplicationExt(16904): inside appext
01-29 14:13:10.720: E/RegisterActivity(16904): in onresume in registeractivity
01-29 14:13:10.880: D/libEGL(16904): loaded /system/lib/egl/libEGL_tegra.so
01-29 14:13:11.000: D/libEGL(16904): loaded /system/lib/egl/libGLESv1_CM_tegra.so
01-29 14:13:11.030: D/libEGL(16904): loaded /system/lib/egl/libGLESv2_tegra.so
01-29 14:13:11.070: D/OpenGLRenderer(16904): Enabling debug mode 0
01-29 14:13:18.390: E/ApplicationExt(16904): extStorageAppCachePath = /mnt/sdcard/Android/data/com.bmi.bmitestapp/cache
01-29 14:13:18.390: D/webview(16904): [InitTabEffectPivot] >> nScreenWidth = 720
01-29 14:13:18.390: D/webview(16904): [InitTabEffectPivot] >> nScreenHeight = 1280
01-29 14:13:18.390: D/sqliteDatabaseCpp(16904): Registering sqlite logging func: /data/data/com.bmi.bmitestapp/databases/webview.db
01-29 14:13:18.390: D/sqliteDatabaseCpp(16904): DB info: open db,path = /data/data/com.bmi.bmitestapp/databases,key = sefraes,flag = 6,cannot stat file,errno = 2,message = No such file or directory
01-29 14:13:18.400: E/MainActivity(16904): in onCreate in mainactivity
01-29 14:13:18.400: D/sqliteDatabaseCpp(16904): DB info: path = /data/data/com.bmi.bmitestapp/databases,handle: 0x1f9a858,type: w,r/w: (0,1),mode: delete,disk free size: 1276 M
01-29 14:13:18.400: D/GCMRegistrar(16904): resetting backoff for com.bmi.bmitestapp
01-29 14:13:18.420: V/GCMRegistrar(16904): Registering app com.bmi.bmitestapp of senders 598080744593
01-29 14:13:18.430: E/ApplicationExt(16904): extStorageAppCachePath = /mnt/sdcard/Android/data/com.bmi.bmitestapp/cache
01-29 14:13:18.430: E/MainActivity(16904): appCachePath = /mnt/sdcard/Android/data/com.bmi.bmitestapp/cache
01-29 14:13:18.430: E/MainActivity(16904): we have a network connection
01-29 14:13:18.430: E/MainActivity(16904): in onResume in mainactivity
01-29 14:13:18.490: W/webcore(16904): java.lang.Throwable: EventHub.removeMessages(int what = 107) is not supported before the WebViewCore is set up.
01-29 14:13:18.490: W/webcore(16904):   at android.webkit.WebViewCore$EventHub.removeMessages(WebViewCore.java:1974)
01-29 14:13:18.490: W/webcore(16904):   at android.webkit.WebViewCore$EventHub.access$9100(WebViewCore.java:1008)
01-29 14:13:18.490: W/webcore(16904):   at android.webkit.WebViewCore.removeMessages(WebViewCore.java:2215)
01-29 14:13:18.490: W/webcore(16904):   at android.webkit.WebView.sendOurVisibleRect(WebView.java:3285)
01-29 14:13:18.490: W/webcore(16904):   at android.webkit.ZoomManager.setZoomScale(ZoomManager.java:772)
01-29 14:13:18.490: W/webcore(16904):   at android.webkit.ZoomManager.access$1900(ZoomManager.java:59)
01-29 14:13:18.490: W/webcore(16904):   at android.webkit.ZoomManager$PostScale.run(ZoomManager.java:1345)
01-29 14:13:18.490: W/webcore(16904):   at android.os.Handler.handleCallback(Handler.java:608)
01-29 14:13:18.490: W/webcore(16904):   at android.os.Handler.dispatchMessage(Handler.java:92)
01-29 14:13:18.490: W/webcore(16904):   at android.os.Looper.loop(Looper.java:156)
01-29 14:13:18.490: W/webcore(16904):   at android.app.ActivityThread.main(ActivityThread.java:5045)
01-29 14:13:18.490: W/webcore(16904):   at java.lang.reflect.Method.invokeNative(Native Method)
01-29 14:13:18.490: W/webcore(16904):   at java.lang.reflect.Method.invoke(Method.java:511)
01-29 14:13:18.490: W/webcore(16904):   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
01-29 14:13:18.490: W/webcore(16904):   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
01-29 14:13:18.490: W/webcore(16904):   at dalvik.system.NativeStart.main(Native Method)
01-29 14:13:18.500: W/webcore(16904): java.lang.Throwable: EventHub.removeMessages(int what = 105) is not supported before the WebViewCore is set up.
01-29 14:13:18.500: W/webcore(16904):   at android.webkit.WebViewCore$EventHub.removeMessages(WebViewCore.java:1974)
01-29 14:13:18.500: W/webcore(16904):   at android.webkit.WebViewCore$EventHub.access$9100(WebViewCore.java:1008)
01-29 14:13:18.500: W/webcore(16904):   at android.webkit.WebViewCore.removeMessages(WebViewCore.java:2215)
01-29 14:13:18.500: W/webcore(16904):   at android.webkit.WebView.sendViewSizeZoom(WebView.java:3520)
01-29 14:13:18.500: W/webcore(16904):   at android.webkit.ZoomManager.setZoomScale(ZoomManager.java:778)
01-29 14:13:18.500: W/webcore(16904):   at android.webkit.ZoomManager.access$1900(ZoomManager.java:59)
01-29 14:13:18.500: W/webcore(16904):   at android.webkit.ZoomManager$PostScale.run(ZoomManager.java:1345)
01-29 14:13:18.500: W/webcore(16904):   at android.os.Handler.handleCallback(Handler.java:608)
01-29 14:13:18.500: W/webcore(16904):   at android.os.Handler.dispatchMessage(Handler.java:92)
01-29 14:13:18.500: W/webcore(16904):   at android.os.Looper.loop(Looper.java:156)
01-29 14:13:18.500: W/webcore(16904):   at android.app.ActivityThread.main(ActivityThread.java:5045)
01-29 14:13:18.500: W/webcore(16904):   at java.lang.reflect.Method.invokeNative(Native Method)
01-29 14:13:18.500: W/webcore(16904):   at java.lang.reflect.Method.invoke(Method.java:511)
01-29 14:13:18.500: W/webcore(16904):   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
01-29 14:13:18.500: W/webcore(16904):   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
01-29 14:13:18.500: W/webcore(16904):   at dalvik.system.NativeStart.main(Native Method)
01-29 14:13:18.530: D/OpenGLRenderer(16904): Flushing caches (mode 0)
01-29 14:13:18.570: I/sqliteDatabaseCpp(16904): sqlite returned: error code = 1,msg = no such table: CacheGroups
01-29 14:13:18.570: I/sqliteDatabaseCpp(16904): sqlite returned: error code = 1,msg = no such table: Caches
01-29 14:13:18.570: I/sqliteDatabaseCpp(16904): sqlite returned: error code = 1,msg = no such table: Origins
01-29 14:13:18.570: I/sqliteDatabaseCpp(16904): sqlite returned: error code = 1,msg = no such table: DeletedCacheResources
01-29 14:13:18.850: E/ApplicationExt(16904): extStorageAppCachePath = /mnt/sdcard/Android/data/com.bmi.bmitestapp/cache
01-29 14:13:19.330: I/PRIME(16904): <CallBackProxy> Send to WebViewClient.
01-29 14:13:19.370: V/GCMBroadcastReceiver(16904): onReceive: com.google.android.c2dm.intent.REGISTRATION
01-29 14:13:19.370: V/GCMBroadcastReceiver(16904): GCM IntentService class: com.bmi.bmitestapp.GCMIntentService
01-29 14:13:19.370: V/GCMBaseIntentService(16904): Acquiring wakelock
01-29 14:13:19.460: V/GCMBaseIntentService(16904): Intent service name: GCMIntentService-598080744593-1
01-29 14:13:19.470: E/GCMRegistrar(16904): internal error: retry receiver class not set yet
01-29 14:13:19.480: V/GCMRegistrar(16904): Registering receiver
01-29 14:13:19.480: D/GCMBaseIntentService(16904): handleRegistration: registrationId = APA91bFytZvnkmsEVHSnw5VRxIwfPRmPsSRVrgRNRa5ww3oqCfnLEZMaBBNtQtlZoK4RD4VQXfAfKDsQUa53PwQBH_rwuI_gEEdHQhxadpBVmJ7L3Dxy90Bzryg_aCWx20-cdZ32cbiiaGR3zUMjpqZizYQbnARN4w,error = null,unregistered = null
01-29 14:13:19.480: D/GCMRegistrar(16904): resetting backoff for com.bmi.bmitestapp
01-29 14:13:19.480: V/GCMRegistrar(16904): Saving regId on app version 1
01-29 14:13:19.490: I/GCMIntentService(16904): Device registered: regId = APA91bFytZvnkmsEVHSnw5VRxIwfPRmPsSRVrgRNRa5ww3oqCfnLEZMaBBNtQtlZoK4RD4VQXfAfKDsQUa53PwQBH_rwuI_gEEdHQhxadpBVmJ7L3Dxy90Bzryg_aCWx20-cdZ32cbiiaGR3zUMjpqZizYQbnARN4w
01-29 14:13:19.490: D/NAME(16904): hardcoded client name
01-29 14:13:19.490: I/bmi GCM(16904): registering device (regId = APA91bFytZvnkmsEVHSnw5VRxIwfPRmPsSRVrgRNRa5ww3oqCfnLEZMaBBNtQtlZoK4RD4VQXfAfKDsQUa53PwQBH_rwuI_gEEdHQhxadpBVmJ7L3Dxy90Bzryg_aCWx20-cdZ32cbiiaGR3zUMjpqZizYQbnARN4w)
01-29 14:13:19.490: D/bmi GCM(16904): Attempt #1 to register
01-29 14:13:19.500: V/bmi GCM(16904): Posting 'email=hardcoded email&regId=APA91bFytZvnkmsEVHSnw5VRxIwfPRmPsSRVrgRNRa5ww3oqCfnLEZMaBBNtQtlZoK4RD4VQXfAfKDsQUa53PwQBH_rwuI_gEEdHQhxadpBVmJ7L3Dxy90Bzryg_aCWx20-cdZ32cbiiaGR3zUMjpqZizYQbnARN4w&name=hardcoded client name' to http://mobilewebexpert.co.uk/pushtest/register.PHP
01-29 14:13:19.500: E/URL(16904): > http://mobilewebexpert.co.uk/pushtest/register.PHP
01-29 14:13:20.610: V/GCMRegistrar(16904): Setting registeredOnServer status as true until 2013-02-05 14:13:20.617
01-29 14:13:20.620: V/GCMBaseIntentService(16904): Releasing wakelock
01-29 14:13:21.470: D/skia(16904): notifyPluginsOnFrameLoad not postponed
01-29 14:13:21.570: D/sqliteDatabase(16904): Create pool connection
01-29 14:13:21.570: D/sqliteDatabaseCpp(16904): DB info: open db,flag = 1,file size = 12288
01-29 14:13:21.570: D/sqliteDatabaseCpp(16904): DB info: path = /data/data/com.bmi.bmitestapp/databases,handle: 0x2797350,type: r,r/w: (1,mode: wal,disk free size: 1276 M

.

这是我关闭网络适配器后的日志记录.

01-29 14:16:57.080: E/RegisterActivity(16904): in onresume in registeractivity
01-29 14:17:03.490: D/webview(16904): [InitTabEffectPivot] >> nScreenWidth = 720
01-29 14:17:03.490: D/webview(16904): [InitTabEffectPivot] >> nScreenHeight = 1280
01-29 14:17:03.490: E/MainActivity(16904): in onCreate in mainactivity
01-29 14:17:03.490: V/GCMRegistrar(16904): Is registered on server: true
01-29 14:17:03.500: E/ApplicationExt(16904): extStorageAppCachePath = /mnt/sdcard/Android/data/com.bmi.bmitestapp/cache
01-29 14:17:03.500: E/MainActivity(16904): appCachePath = /mnt/sdcard/Android/data/com.bmi.bmitestapp/cache
01-29 14:17:03.500: E/MainActivity(16904): we don't have a network connection
01-29 14:17:03.500: E/MainActivity(16904): in onResume in mainactivity
01-29 14:17:03.500: D/chromium(16904): Unknown chromium error: -400
01-29 14:17:03.540: D/skia(16904): notifyPluginsOnFrameLoad not postponed
01-29 14:17:03.580: D/OpenGLRenderer(16904): Flushing caches (mode 0)

有一点我注意到,它可能没什么,但注册性是指调用MainActivity的活动. RegisterActivity只有一个按钮,可以触发MainActivity的Intent.网络适​​配器关闭后,我必须按下registerAcivity上的按钮,该按钮调用MainActivity中的onCreate.它就像是一个MainActivity的新实例？这可能会影响webview的缓存.实际上,必须在此过程中调用主要活动的onDestroy.

另一件事引起了我的注意.

01-29 14:17:03.580: D/OpenGLRenderer(16904): Flushing caches (mode 0)