Android中的WebView後退按鈕問題？

Question

我在我的應用程序中使用webview。

代碼：

webView.getSettings().setJavaScriptEnabled(true); 

    webView.setWebChromeClient(new WebChromeClient() { 
    public void onProgressChanged(WebView view, int progress) 
     { 
      activity.setTitle("Loading..."); 
      activity.setProgress(progress * 100); 

      if(progress == 100){ 

       activity.setTitle(R.string.app_name); 
       //view.canGoBack(); 
      } 
     } 
    }); 


    webView.setWebViewClient(new WebViewClient() { 

     @Override 
     public void onPageStarted(WebView view, String url, Bitmap favicon) { 
      // TODO Auto-generated method stub 
      super.onPageStarted(view, url, favicon); 
     } 

     @Override 
     public void onPageFinished(WebView view, String url) { 
      // TODO Auto-generated method stub 
      view.canGoBack(); 
      super.onPageFinished(view, url); 
     } 

    }); 
    //The URL that webview is loading 
    webView.loadUrl(uri); 
} 

@Override 
public boolean onKeyDown(int keyCode, KeyEvent event) { 
    // TODO Auto-generated method stub 
    if ((keyCode == KeyEvent.KEYCODE_BACK) && webView.canGoBack()) { 
     webView.goBack(); 
     return true;    
      } 
     return super.onKeyDown(keyCode, event); 
} 

當我按按後退按鈕，該應用程序是崩潰和在logcat中產生一個錯誤

07-29 12:47:56.341: ERROR/AndroidRuntime(10567): Uncaught handler: thread main exiting due to uncaught exception 
07-29 12:47:56.401: ERROR/AndroidRuntime(10567): java.lang.NullPointerException 
07-29 12:47:56.401: ERROR/AndroidRuntime(10567):  at com.MyDemo.WebViewActivity.onKeyDown(SiteViewActivity.java:74) 
07-29 12:47:56.401: ERROR/AndroidRuntime(10567):  at android.view.KeyEvent.dispatch(KeyEvent.java:1069) 
07-29 12:47:56.401: ERROR/AndroidRuntime(10567):  at android.app.Activity.dispatchKeyEvent(Activity.java:1980) 
07-29 12:47:56.401: ERROR/AndroidRuntime(10567):  at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchKeyEvent(PhoneWindow.java:1724) 
07-29 12:47:56.401: ERROR/AndroidRuntime(10567):  at android.view.ViewRoot.deliverKeyEventToViewHierarchy(ViewRoot.java:2424) 
07-29 12:47:56.401: ERROR/AndroidRuntime(10567):  at android.view.ViewRoot.handleFinishedEvent(ViewRoot.java:2394) 
07-29 12:47:56.401: ERROR/AndroidRuntime(10567):  at android.view.ViewRoot.handleMessage(ViewRoot.java:1726) 
07-29 12:47:56.401: ERROR/AndroidRuntime(10567):  at android.os.Handler.dispatchMessage(Handler.java:99) 
07-29 12:47:56.401: ERROR/AndroidRuntime(10567):  at android.os.Looper.loop(Looper.java:123) 
07-29 12:47:56.401: ERROR/AndroidRuntime(10567):  at android.app.ActivityThread.main(ActivityThread.java:3948) 
07-29 12:47:56.401: ERROR/AndroidRuntime(10567):  at java.lang.reflect.Method.invokeNative(Native Method) 
07-29 12:47:56.401: ERROR/AndroidRuntime(10567):  at java.lang.reflect.Method.invoke(Method.java:521) 
07-29 12:47:56.401: ERROR/AndroidRuntime(10567):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:782) 
07-29 12:47:56.401: ERROR/AndroidRuntime(10567):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:540) 
07-29 12:47:56.401: ERROR/AndroidRuntime(10567):  at dalvik.system.NativeStart.main(Native Method) 

我想回到以前的網頁，在網頁視圖。

Answer 1

也許這篇文章將幫助您：

How to go back to previous page if back button is pressed in WebView?

問候