WebView在頁面加載後顯示白屏

Question

我有一個WebView應該加載網站的移動版本，但是當我嘗試在WebView內加載它時，它只會顯示爲白色屏幕。我曾嘗試在我的android瀏覽器中加載相同的URL，並在我的桌面上使用User-Agent Switcher。我知道頁面也已經完成加載，因爲我有一個onPageFinished（）方法，當頁面顯示時顯示一個toast。每次我加載應用程序時，我都會看到一個白色屏幕，然後幾秒鐘後，Toast消息。

編輯：我已經嘗試了不同的移動網站，他們都在WebView中的工作，就是給我找麻煩的只有一個是這一個：https://zangleweb01.clovisusd.k12.ca.us/StudentConnect/Home/Login

MainActivity.java

package com.student.connect; 

import android.annotation.SuppressLint; 
import android.annotation.TargetApi; 
import android.app.ActionBar; 
import android.net.Uri; 
import android.os.Bundle; 
import android.content.Context; 
import android.content.Intent; 
import android.os.Build; 
import android.support.v4.app.FragmentActivity; 
import android.view.KeyEvent; 
import android.view.Menu; 
import android.view.View; 
import android.webkit.DownloadListener; 
import android.webkit.WebSettings; 
import android.webkit.WebView; 
import android.webkit.WebViewClient; 
import android.widget.ArrayAdapter; 
import android.widget.Toast; 

public class MainActivity extends FragmentActivity implements 
     ActionBar.OnNavigationListener { 

    /** 
    * The serialization (saved instance state) Bundle key representing the 
    * current dropdown position. 
    */ 
    private static final String STATE_SELECTED_NAVIGATION_ITEM = "selected_navigation_item"; 
    @SuppressWarnings("unused") 
    private WebView student_zangle; 

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

     // Set up the action bar to show a dropdown list. 
     final ActionBar actionBar = getActionBar(); 
     actionBar.setDisplayShowTitleEnabled(false); 
     actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_LIST); 

     // Set up the dropdown list navigation in the action bar. 
     actionBar.setListNavigationCallbacks(
     // Specify a SpinnerAdapter to populate the dropdown list. 
       new ArrayAdapter<String>(getActionBarThemedContextCompat(), 
         android.R.layout.simple_list_item_1, 
         android.R.id.text1, new String[] { 
           getString(R.string.title_section1), 
           getString(R.string.title_section2), 
           getString(R.string.title_section3), }), this); 
    } 

    /** 
    * Backward-compatible version of {@link ActionBar#getThemedContext()} that 
    * simply returns the {@link android.app.Activity} if 
    * <code>getThemedContext</code> is unavailable. 
    */ 
    @TargetApi(Build.VERSION_CODES.ICE_CREAM_SANDWICH) 
    private Context getActionBarThemedContextCompat() { 
     if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) { 
      return getActionBar().getThemedContext(); 
     } else { 
      return this; 
     } 
    } 

    @Override 
    public void onRestoreInstanceState(Bundle savedInstanceState) { 
     // Restore the previously serialized current dropdown position. 
     if (savedInstanceState.containsKey(STATE_SELECTED_NAVIGATION_ITEM)) { 
      getActionBar().setSelectedNavigationItem(
        savedInstanceState.getInt(STATE_SELECTED_NAVIGATION_ITEM)); 
     } 
    } 

    @Override 
    public void onSaveInstanceState(Bundle outState) { 
     // Serialize the current dropdown position. 
     outState.putInt(STATE_SELECTED_NAVIGATION_ITEM, getActionBar() 
       .getSelectedNavigationIndex()); 
    } 

    @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; 
    } 

    @SuppressLint("NewApi") 
    @Override 
    public boolean onNavigationItemSelected(int position, long id) 
    { 
     WebView student_zangle = (WebView) findViewById(R.id.student_zangle); 
     student_zangle.setWebViewClient(new YourWebClient()); 
     student_zangle.loadUrl("https://zangleweb01.clovisusd.k12.ca.us/StudentConnect/Home/Login"); 
     student_zangle.setDrawingCacheEnabled(false); 
     WebSettings settings = student_zangle.getSettings(); 
     student_zangle.setScrollBarStyle(View.SCROLLBARS_INSIDE_OVERLAY); 
     settings.setJavaScriptEnabled(true); 
     settings.setJavaScriptCanOpenWindowsAutomatically(true); 
     settings.setAllowUniversalAccessFromFileURLs(true); 
     settings.setAllowContentAccess(true); 

     student_zangle.setDownloadListener(new DownloadListener() 
     { 
      public void onDownloadStart(String url, String userAgent, 
        String contentDisposition, String mimetype, long contentLength) 
      { 
       Intent intent = new Intent(Intent.ACTION_VIEW); 
       intent.setType("application/x-rar-compressed"); 
       intent.setData(Uri.parse(url)); 
       startActivity(intent); 
      } 
     }); 
     return true; 
    } 


    @Override 
     public boolean onKeyDown(int keyCode, KeyEvent event) { 
     if (keyCode == KeyEvent.KEYCODE_BACK) { 
      moveTaskToBack(true); 
     } 
     return super.onKeyDown(keyCode, event); 
     } 

    private class YourWebClient extends WebViewClient {  
     @Override 
     public boolean shouldOverrideUrlLoading(WebView view, String url) { 
      if (url.contains("mailto")) 
      { 
       String mail = url.replaceFirst("mailto:", ""); 
       Intent intent = new Intent(Intent.ACTION_SEND); 
       intent.setType("message/rfc822"); 
       intent.putExtra(Intent.EXTRA_EMAIL, mail); 
       startActivity(intent); 
       return true;    
      } 
      view.loadUrl(url); 
      return true; 
     } 
     public void onPageFinished(WebView view, String url) 
     { 
      Toast.makeText(getApplicationContext(), "done", 
         Toast.LENGTH_LONG).show(); 
     } 
    } 
} 

Answer 1

嘗試buildDrawingCache有以下變化：

student_zangle.setDrawingCacheEnabled(true); 
student_zangle.buildDrawingCache(); 

注意：應避免調用此方法時硬件減速已啓用