3

我制作了一个包含 webview 的应用程序，可以在需要时切换缓存模式。从加载默认到加载缓存其他网络。我遇到的第一个问题是在警报对话框处于活动状态时更改方向时应用程序崩溃。我所做的是当我输入时控制方向变化：

    this.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_SENSOR);

在构建 webview 的方法上，我放了：

    this.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_NOSENSOR);

在调用警报对话框的方法上。但是现在，问题是当缓存模式设置为加载缓存其他网络时应用程序崩溃，正在加载缓存并且方向已更改。我确信只有在加载缓存时才会出现此错误，因为根据我的测试，再次建立连接时它会再次正常工作。

以下是我的主要活动的完整代码，当然没有导入：

public class MainActivity extends Activity
{

    private WebView wv;
    private ProgressBar progress;
    private static String mycaturl="www.sampleurl1.com";
    private static String errurl="www.sampleurl2.com";

    @SuppressLint("NewApi")
    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);     
        StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitNetwork().build();
        StrictMode.setThreadPolicy(policy);
        if (reachable(this))
        {
            Toast.makeText(this, "Reachable", Toast.LENGTH_SHORT).show();
            buildwv( savedInstanceState, WebSettings.LOAD_DEFAULT, mycaturl );
        }
        else
        {
            Toast.makeText(this, "Unreachable", Toast.LENGTH_SHORT).show();
            eolc( savedInstanceState );
        }
    }


    @SuppressLint({ "SetJavaScriptEnabled" })
    public void buildwv(Bundle sis, int load, String url)
    {
        this.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_SENSOR);

        setContentView(R.layout.activity_main);

        //assigning objects to variables
        wv=(WebView) findViewById(R.id.wv);
        wv.setWebViewClient( new wvc() );
        progress=(ProgressBar) findViewById(R.id.progress);

        //websettings
        WebSettings ws = wv.getSettings();
        ws.setAppCacheMaxSize( 100 * 1024 * 1024 ); // 100MB
        ws.setAppCachePath( this.getCacheDir().getAbsolutePath() );
        ws.setAllowFileAccess( true );
        ws.setAppCacheEnabled( true );
        ws.setJavaScriptEnabled( true );
        ws.setCacheMode(load);

        //if instance is saved, to catch orientation change
        if(sis==null)
        {   wv.loadUrl(url);    }
    }


    public void eolc(final Bundle sis)
    {
        this.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_NOSENSOR);

        AlertDialog.Builder alertDialog = new AlertDialog.Builder( MainActivity.this );

        alertDialog.setTitle("PATAY ANG WA-LA!!");
        alertDialog.setMessage("Host is unreachable. Load from cache or exit.");
        alertDialog.setIcon(R.drawable.tick);
        //alertDialog.setCanceledOnTouchOutside(false);
        alertDialog.setCancelable(false);

        alertDialog.setPositiveButton( "Load from Cache", new DialogInterface.OnClickListener()
        {
            public void onClick(DialogInterface dialog,int which)
            {
                // Write your code here to execute after dialog
                Toast.makeText(getApplicationContext(), "You chose to load cache.", Toast.LENGTH_SHORT).show();
                buildwv( sis, WebSettings.LOAD_CACHE_ELSE_NETWORK, mycaturl );
            }
        });

        alertDialog.setNeutralButton( "Help", new DialogInterface.OnClickListener()
        {
            public void onClick(DialogInterface dialog, int which)
            {
                Toast.makeText(getApplicationContext(), "You chose Help. EOLC", Toast.LENGTH_SHORT).show();

                buildwv( sis, WebSettings.LOAD_CACHE_ELSE_NETWORK, errurl );
            }
        });

        alertDialog.setNegativeButton( "Exit", new DialogInterface.OnClickListener()
        {
            public void onClick(DialogInterface dialog, int which)
            {
                // Write your code here to execute after dialog
                Toast.makeText(getApplicationContext(), "You chose to exit.", Toast.LENGTH_SHORT).show();
                finish();
            }
        });

        alertDialog.create();
        alertDialog.show();
    }


    public void roe()
    {
        this.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_NOSENSOR);

        AlertDialog.Builder alertDialog = new AlertDialog.Builder( MainActivity.this );

        alertDialog.setTitle("TANGA ANG WA-LA!!");
        alertDialog.setMessage("Host is unreachable. Restart to load cache or exit.");
        alertDialog.setIcon(R.drawable.tick);
        alertDialog.setCancelable(false);

        alertDialog.setPositiveButton( "Restart", new DialogInterface.OnClickListener()
        {
            public void onClick(DialogInterface dialog,int which)
            {
                Toast.makeText(getApplicationContext(), "You chose to restart and load cache.", Toast.LENGTH_SHORT).show();
                Intent i = getBaseContext().getPackageManager()
                         .getLaunchIntentForPackage( getBaseContext().getPackageName() );
                i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_NEW_TASK );
                startActivity(i);
            }
        });

        alertDialog.setNeutralButton( "Help", new DialogInterface.OnClickListener()
        {
            public void onClick(DialogInterface dialog, int which)
            {
                Toast.makeText(getApplicationContext(), "You chose Help. ROE", Toast.LENGTH_SHORT).show();
                wv.stopLoading();
                wv.loadUrl( errurl );
            }
        });

        alertDialog.setNegativeButton( "Exit", new DialogInterface.OnClickListener()
        {
            public void onClick(DialogInterface dialog, int which)
            {
                Toast.makeText(getApplicationContext(), "You chose to exit.", Toast.LENGTH_SHORT).show();
                finish();
            }
        });

        alertDialog.create();
        alertDialog.show();
    }


    private class wvc extends WebViewClient
    {

          //when page started loading
          public void onPageStarted(WebView view, String url, Bitmap favicon)
          {
              //circular progress bar open
              progress.setVisibility(View.VISIBLE);

              //if reachable and setting cache on every new page
              //setcache(getApplicationContext()); 

              if (url==mycaturl)
              {
                  WebSettings ws = wv.getSettings();

                  if ( !reachable(getApplicationContext()) )
                  {
                      if ( ws.getCacheMode() == WebSettings.LOAD_DEFAULT )
                      {
                          roe();
                      }
                      else if ( ws.getCacheMode() == WebSettings.LOAD_CACHE_ELSE_NETWORK )
                      {
                          Toast.makeText(getApplicationContext(), "loading cache coz not reachable", Toast.LENGTH_SHORT).show();
                      }
                      else
                      {
                          Toast.makeText(getApplicationContext(), "websetting out of range", Toast.LENGTH_SHORT).show();
                      }
                  }
              }
          }


          //when page finished
          @Override
          public void onPageFinished(WebView view, String url) 
          {
              super.onPageFinished(view, mycaturl);
              Toast.makeText(getApplicationContext(), "PAGE DONE LOADING!!", Toast.LENGTH_SHORT).show();

              //circular progress bar close
              progress.setVisibility(View.GONE);
          }


          //when received an error
          @Override
          public void onReceivedError(WebView view, int errorCode, String description, String failingUrl)
          {
              wv.stopLoading();
              //wv.loadUrl("file:///android_asset/otherpages/errorpage.htm");
              WebSettings ws = wv.getSettings();

              if ( ws.getCacheMode() == WebSettings.LOAD_DEFAULT )
              {
                  Toast.makeText(getApplicationContext(), "Page unavailable", Toast.LENGTH_SHORT).show();
              }
              else
              {
                  Toast.makeText(getApplicationContext(), "Page not cached", Toast.LENGTH_SHORT).show();
              }
              roe();
          }
      }


    //checking connectivity by checking if site is reachable
    public static boolean reachable(Context context) 
    {
        final ConnectivityManager connMgr = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
        final NetworkInfo netInfo = connMgr.getActiveNetworkInfo();

        if (netInfo != null && netInfo.isConnected()) 
        {
            try 
            {
                URL url = new URL(mycaturl);
                HttpURLConnection urlc = (HttpURLConnection) url.openConnection();
                urlc.setConnectTimeout(5000); // five seconds timeout in milliseconds
                urlc.connect();
                if (urlc.getResponseCode() == 200) // good response
                {   return true;    } else {    return false;   }
            }
            catch (IOException e)
            {   return false;   }
        }
        else
        {   return false;   }
    }


    //options menu inflation
    @Override
    public boolean onCreateOptionsMenu(Menu menu) 
    {
        // inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }


    //when back button is pressed
    public void onBackPressed ()
    {
        if (wv.isFocused() && wv.canGoBack())
        {   wv.goBack();    }   else {  finish();   }
    }


    //when options button is pressed
    @Override

    public boolean onOptionsItemSelected(MenuItem item)
    {
        switch (item.getItemId())
        {
            case R.id.item1:
                wv.loadUrl( errurl );
                break;
            case R.id.item2:
                String currurl=wv.getUrl();
                wv.loadUrl(currurl);   
                break;
            case R.id.item3:
                Intent i = getBaseContext().getPackageManager()
                 .getLaunchIntentForPackage( getBaseContext().getPackageName() );
                i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
                startActivity(i);
                break;
            case R.id.item4:
                finish();
                break;
            default:
                break;
        }
        return true;
    } 


    //saving instance state
    @Override
    protected void onSaveInstanceState(Bundle outState )
    {
        super.onSaveInstanceState(outState);
        wv.saveState(outState);
    }


    //restoring instance state
    @Override
    protected void onRestoreInstanceState(Bundle savedInstanceState)
    {
        super.onSaveInstanceState(savedInstanceState);
        wv.restoreState(savedInstanceState);
    }

}

这是我的清单：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.msiecsapps.mycatlog"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="17" />

    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" /> 

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.msiecsapps.mycatlog.Splash"
            android:label="@string/app_name" 
            android:theme="@android:style/Theme.NoTitleBar.Fullscreen" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <activity
            android:name="com.msiecsapps.mycatlog.MainActivity"
            android:label="@string/app_name" >
        </activity>
    </application>

</manifest>

以下是 Logcat 上显示的一些内容：

08-23 15:23:13.615: V/MediaPlayer(31183): disconnect
08-23 15:23:13.615: V/MediaPlayer(31183): destructor
08-23 15:23:13.615: W/SurfaceView(31183): CHECK surface infomation creating=false formatChanged=false sizeChanged=false visible=false visibleChanged=true surfaceChanged=true realSizeChanged=false redrawNeeded=false left=false top=false
08-23 15:23:13.650: V/MediaPlayer(31183): disconnect
08-23 15:23:47.375: I/webclipboard(31183): clipservice: android.sec.clipboard.ClipboardExManager@41eaae10
08-23 15:23:47.470: V/webkit(31183): BrowserFrame constructor: this=Handler (android.webkit.BrowserFrame) {41eaac20}
08-23 15:23:47.610: E/SpannableStringBuilder(31183): SPAN_EXCLUSIVE_EXCLUSIVE spans cannot have a zero length
08-23 15:23:47.610: E/SpannableStringBuilder(31183): SPAN_EXCLUSIVE_EXCLUSIVE spans cannot have a zero length
08-23 15:23:47.705: I/GATE(31183): <GATE-M>DEV_ACTION_COMPLETED</GATE-M>
08-23 15:23:51.575: D/dalvikvm(31183): GC_CONCURRENT freed 215K, 9% free 13356K/14599K, paused 2ms+3ms, total 29ms
08-23 15:23:51.580: V/MediaPlayer-JNI(31183): native_finalize
08-23 15:23:51.580: V/MediaPlayer-JNI(31183): release
08-23 15:23:51.620: D/AndroidRuntime(31183): Shutting down VM
08-23 15:23:51.620: W/dalvikvm(31183): threadid=1: thread exiting with uncaught exception (group=0x410a82a0)
08-23 15:23:51.630: E/AndroidRuntime(31183): FATAL EXCEPTION: main
08-23 15:23:51.630: E/AndroidRuntime(31183): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.msiecsapps.mycatlog/com.msiecsapps.mycatlog.MainActivity}: java.lang.NullPointerException
08-23 15:23:51.630: E/AndroidRuntime(31183):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2100)
08-23 15:23:51.630: E/AndroidRuntime(31183):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2125)
08-23 15:23:51.630: E/AndroidRuntime(31183):    at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:3553)
08-23 15:23:51.630: E/AndroidRuntime(31183):    at android.app.ActivityThread.access$700(ActivityThread.java:140)
08-23 15:23:51.630: E/AndroidRuntime(31183):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1233)
08-23 15:23:51.630: E/AndroidRuntime(31183):    at android.os.Handler.dispatchMessage(Handler.java:99)
08-23 15:23:51.630: E/AndroidRuntime(31183):    at android.os.Looper.loop(Looper.java:137)
08-23 15:23:51.630: E/AndroidRuntime(31183):    at android.app.ActivityThread.main(ActivityThread.java:4898)
08-23 15:23:51.630: E/AndroidRuntime(31183):    at java.lang.reflect.Method.invokeNative(Native Method)
08-23 15:23:51.630: E/AndroidRuntime(31183):    at java.lang.reflect.Method.invoke(Method.java:511)
08-23 15:23:51.630: E/AndroidRuntime(31183):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1006)
08-23 15:23:51.630: E/AndroidRuntime(31183):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:773)
08-23 15:23:51.630: E/AndroidRuntime(31183):    at dalvik.system.NativeStart.main(Native Method)
08-23 15:23:51.630: E/AndroidRuntime(31183): Caused by: java.lang.NullPointerException
08-23 15:23:51.630: E/AndroidRuntime(31183):    at com.msiecsapps.mycatlog.MainActivity.onRestoreInstanceState(MainActivity.java:332)
08-23 15:23:51.630: E/AndroidRuntime(31183):    at android.app.Activity.performRestoreInstanceState(Activity.java:944)
08-23 15:23:51.630: E/AndroidRuntime(31183):    at android.app.Instrumentation.callActivityOnRestoreInstanceState(Instrumentation.java:1134)
08-23 15:23:51.630: E/AndroidRuntime(31183):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2078)
08-23 15:23:51.630: E/AndroidRuntime(31183):    ... 12 more
08-23 15:24:06.700: I/Process(31183): Sending signal. PID: 31183 SIG: 9
08-23 15:24:07.240: D/AndroidRuntime(1122): Shutting down VM
08-23 15:24:07.240: W/dalvikvm(1122): threadid=1: thread exiting with uncaught exception (group=0x410a82a0)
08-23 15:24:07.245: E/AndroidRuntime(1122): FATAL EXCEPTION: main
08-23 15:24:07.245: E/AndroidRuntime(1122): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.msiecsapps.mycatlog/com.msiecsapps.mycatlog.MainActivity}: java.lang.NullPointerException
08-23 15:24:07.245: E/AndroidRuntime(1122):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2100)
08-23 15:24:07.245: E/AndroidRuntime(1122):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2125)
08-23 15:24:07.245: E/AndroidRuntime(1122):     at android.app.ActivityThread.access$600(ActivityThread.java:140)
08-23 15:24:07.245: E/AndroidRuntime(1122):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1227)
08-23 15:24:07.245: E/AndroidRuntime(1122):     at android.os.Handler.dispatchMessage(Handler.java:99)
08-23 15:24:07.245: E/AndroidRuntime(1122):     at android.os.Looper.loop(Looper.java:137)
08-23 15:24:07.245: E/AndroidRuntime(1122):     at android.app.ActivityThread.main(ActivityThread.java:4898)
08-23 15:24:07.245: E/AndroidRuntime(1122):     at java.lang.reflect.Method.invokeNative(Native Method)
08-23 15:24:07.245: E/AndroidRuntime(1122):     at java.lang.reflect.Method.invoke(Method.java:511)
08-23 15:24:07.245: E/AndroidRuntime(1122):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1006)
08-23 15:24:07.245: E/AndroidRuntime(1122):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:773)
08-23 15:24:07.245: E/AndroidRuntime(1122):     at dalvik.system.NativeStart.main(Native Method)
08-23 15:24:07.245: E/AndroidRuntime(1122): Caused by: java.lang.NullPointerException
08-23 15:24:07.245: E/AndroidRuntime(1122):     at com.msiecsapps.mycatlog.MainActivity.onRestoreInstanceState(MainActivity.java:332)
08-23 15:24:07.245: E/AndroidRuntime(1122):     at android.app.Activity.performRestoreInstanceState(Activity.java:944)
08-23 15:24:07.245: E/AndroidRuntime(1122):     at android.app.Instrumentation.callActivityOnRestoreInstanceState(Instrumentation.java:1134)
08-23 15:24:07.245: E/AndroidRuntime(1122):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2078)
08-23 15:24:07.245: E/AndroidRuntime(1122):     ... 11 more

我认为这些日志是从我的初始屏幕断开连接的那一刻起，检查站点是否可访问，在警报对话框中选择从缓存加载（设置缓存模式以加载缓存其他网络），当缓存页面加载时，我倾斜phon 改变方向。在那里，虚拟机被关闭了。

请帮我。提前致谢。

4

1 回答 1

1

在你做任何其他事情之前：

  1. 转到您的设备（手机/平板电脑）上的设置，转到“开发人员设置”并选择“USB-error-report”打开。
  2. 通过 USB 将您的设备连接到您的 PC，瞧：您将看到从您的设备记录的 logcat。

为了能够处理问题/为 android 开发，您将需要上述内容。

之后：“我遇到的第一个问题是，在警报对话框处于活动状态时更改方向时应用程序崩溃” => 后退一步，回到这个问题。您应该能够以其他方式处理此问题，请在此处打印此问题的 logcat 日志，以便我们为您提供帮助。

于 2013-08-22T08:56:58.950 回答