进度对话框第二次在带后退按钮的webview中显示问题

Question

我使用以下代码在webview中显示progressDialog。正常情况下，一切都很好，但在进度对话框加载时，我按下后退按钮，再次与webview进行相同的活动，它不会立即显示进度对话框，但过了一会儿，重复这两到三次应用程序崩溃。

同时显示_dialog.show() onpagstarted。

从onCreateDialog创建的ProgressDialog在第二次运行时停止动画

Android:对话框问题

但是没有用。

谁能指点我一下这个问题的解决办法是什么?

private static final int DIALOG_WEBVIEW = 0;
    private WebView _webView;
    private ProgressDialog _dialog;
oncreate()
{
_webView.canGoBack();
        _webView.setWebViewClient(new WebViewClient() {
            @Override
            public boolean shouldOverrideUrlLoading(WebView view, String url) {              
                view.loadUrl(url);
                return true;
            }

            @Override
            public void onPageStarted(WebView view, String url, Bitmap favicon) {


                showDialog(DIALOG_WEBVIEW); // crashes here
            }
            @Override
            public void onPageFinished(WebView view, String url) {

                if(_dialog.isShowing())
                {
                    removeDialog(DIALOG_WEBVIEW);
                }
            }

            @Override
            public void onReceivedError(WebView view, int errorCode,
                    String description, String failingUrl) {
                if (Constants.LOG)Log.d("recieved error-------------------------", "");
                super.onReceivedError(view, errorCode, description, failingUrl);
                if(_dialog.isShowing())
                {
                    removeDialog(DIALOG_WEBVIEW);
                }
            }

        });

}

@Override
    protected void onPrepareDialog(int id, Dialog dialog) {
        switch (id) {
        case DIALOG_WEBVIEW:
          _dialog.setMessage(Constants.TEXT_PLEASE_WAIT);
            _dialog.setCancelable(true);
            return;
        default:
            return ;
        }
    }
    @Override
    protected Dialog onCreateDialog(int id)
    {
        switch (id)
        {
            case DIALOG_WEBVIEW:
            {
                _dialog = new ProgressDialog(this);
                 _dialog.show();
                 return _dialog;
            }
            default:
                return null;
        }
    }

日志的猫

07-15 11:43:16.744: ERROR/AndroidRuntime(750): android.view.WindowManager$BadTokenException: Unable to add window -- token android.os.BinderProxy@406b7138 is not valid; is your activity running?
07-15 11:43:16.744: ERROR/AndroidRuntime(750):     at android.view.ViewRoot.setView(ViewRoot.java:527)
07-15 11:43:16.744: ERROR/AndroidRuntime(750):     at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:177)
07-15 11:43:16.744: ERROR/AndroidRuntime(750):     at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:91)
07-15 11:43:16.744: ERROR/AndroidRuntime(750):     at android.view.Window$LocalWindowManager.addView(Window.java:424)
07-15 11:43:16.744: ERROR/AndroidRuntime(750):     at android.app.Dialog.show(Dialog.java:241)
07-15 11:43:16.744: ERROR/AndroidRuntime(750):     at com.android.mobile.modules.volunteer.VolunteerScreenNew.onCreateDialog(VolunteerScreenNew.java:343)
07-15 11:43:16.744: ERROR/AndroidRuntime(750):     at android.app.Activity.onCreateDialog(Activity.java:2482)
07-15 11:43:16.744: ERROR/AndroidRuntime(750):     at android.app.Activity.createDialog(Activity.java:882)
07-15 11:43:16.744: ERROR/AndroidRuntime(750):     at android.app.Activity.showDialog(Activity.java:2557)
07-15 11:43:16.744: ERROR/AndroidRuntime(750):     at android.app.Activity.showDialog(Activity.java:2524)
07-15 11:43:16.744: ERROR/AndroidRuntime(750):     at com.android.mobile.modules.volunteer.VolunteerScreenNew$1.onPageStarted(VolunteerScreenNew.java:181)
07-15 11:43:16.744: ERROR/AndroidRuntime(750):     at android.webkit.CallbackProxy.handleMessage(CallbackProxy.java:264)
07-15 11:43:16.744: ERROR/AndroidRuntime(750):     at android.os.Handler.dispatchMessage(Handler.java:99)
07-15 11:43:16.744: ERROR/AndroidRuntime(750):     at android.os.Looper.loop(Looper.java:123)
07-15 11:43:16.744: ERROR/AndroidRuntime(750):     at android.app.ActivityThread.main(ActivityThread.java:3683)
07-15 11:43:16.744: ERROR/AndroidRuntime(750):     at java.lang.reflect.Method.invokeNative(Native Method)
07-15 11:43:16.744: ERROR/AndroidRuntime(750):     at java.lang.reflect.Method.invoke(Method.java:507)
07-15 11:43:16.744: ERROR/AndroidRuntime(750):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
07-15 11:43:16.744: ERROR/AndroidRuntime(750):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
07-15 11:43:16.744: ERROR/AndroidRuntime(750):     at dalvik.system.NativeStart.main(Native Method)

Answer 1

通常，我们可以使用以下代码

来覆盖后退按钮动作

@Override
public boolean onKeyDown(int keyCode, KeyEvent event){
if ( keyCode == KeyEvent.KEYCODE_BACK&& event.getRepeatCount() == 0)
{
onBackPressed();
}
return super.onKeyDown(keyCode, event);
}

创建一个方法onBackPressed()，并取消其中的对话框，并开始另一个活动