做一个FragmentTransaction后WebViewFragment web视图为空 [英] WebViewFragment webView is null after doing a FragmentTransaction

问题描述

目前，我有我的应用程序设置了一个 ListFragment 在右边的左边和 DetailsFragment （类似到下面的片剂的布局）。

I currently have my application set up with a ListFragment on the left and a DetailsFragment on the right (similar to the layout on the tablet below).

在细节的片段（片段列表旁边），我有一个转到的交易按钮，当pressed应更换detailsFragment与 WebViewFragment 。

On the details fragment (fragment next to the list) I have a goto deal button, which when pressed should replace the detailsFragment with a WebViewFragment.

我遇到的问题是，试图加载在webviewfragment一个URL时，的WebView 为空。

The problem I am having is that when trying to load a url in the webviewfragment the WebView is null.

WebViewFragment webViewFragment = new WebViewFragment();

FragmentTransaction transaction = getFragmentManager().beginTransaction();

// Replace whatever is in the fragment_container view with this fragment,
// and add the transaction to the back stack
transaction.replace(R.id.deal_details_fragment, webViewFragment);
transaction.addToBackStack(null);

// Commit the transaction
transaction.commit();

// Set the url
if (webViewFragment.getWebView()==null)
    Log.d("webviewfragment", "is null");
webViewFragment.getWebView().loadUrl("http://www.google.com");

下面是我的主要布局有原来的两个片段定义。

Below is my main layout which has the original two fragments defined.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
          android:id="@+id/main_activity_layout"

    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="horizontal" >

  <fragment
      android:name="com.bencallis.dealpad.DealListFragment"
      android:id="@+id/deal_list_fragment"
      android:layout_weight="1"
      android:layout_width="0px"
      android:layout_height="match_parent" >
      <!-- Preview: layout=@layout/deal_list_fragment -->
  </fragment>
  <fragment
      android:name="com.bencallis.dealpad.DealDetailsFragment"
      android:id="@+id/deal_details_fragment"
      android:layout_weight="2"
      android:layout_width="0px"
      android:layout_height="match_parent" >
      <!-- Preview: layout=@layout/deal_details_fragment -->
  </fragment>

</LinearLayout>

看来，webViewFragment没有被完全创建作为的WebView 尚未初始化。我已经在网上看了，但没有有关的信息非常少的 WebViewFragment 。

It seems that the webViewFragment is not being created fully as the WebView has not been initialised. I have looked online but there is very little information regarding the WebViewFragment.

任何想法如何确保的WebView 被初始化的 WebViewFragment ？

Any ideas how to ensure WebView is initialised in the WebViewFragment?

推荐答案

通过很大的帮助，从Espiandev我设法得到一个工作的WebView。为了确保链接在该片段打开而不是在网络浏览器应用我创建延伸一个简单InnerWebView客户WebViewClinet

With great help from Espiandev I have managed to get a working WebView. To ensure that links opened in the fragment and not in a web browser application I created a simple InnerWebView client which extends WebViewClinet.

public class DealWebViewFragment extends Fragment {

    private WebView mWebView;
    private boolean mIsWebViewAvailable;
    private String mUrl = null;

    /**
     * Creates a new fragment which loads the supplied url as soon as it can
     * @param url the url to load once initialised
     */
    public DealWebViewFragment(String url) {
        super();
        mUrl = url;
    }

    /**
     * Called to instantiate the view. Creates and returns the WebView.
     */
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {

        if (mWebView != null) {
            mWebView.destroy();
        }
        mWebView = new WebView(getActivity());
        mWebView.setOnKeyListener(new OnKeyListener(){


            @Override
            public boolean onKey(View v, int keyCode, KeyEvent event) {
                  if ((keyCode == KeyEvent.KEYCODE_BACK) && mWebView.canGoBack()) {
                        mWebView.goBack();
                        return true;
                    }
                    return false;
            }

        });
        mWebView.setWebViewClient(new InnerWebViewClient()); // forces it to open in app
        mWebView.loadUrl(mUrl);
        mIsWebViewAvailable = true;
        WebSettings settings = mWebView.getSettings();
        settings.setJavaScriptEnabled(true);
        return mWebView;
    }

    /**
     * Convenience method for loading a url. Will fail if {@link View} is not initialised (but won't throw an {@link Exception})
     * @param url
     */
    public void loadUrl(String url) {
        if (mIsWebViewAvailable) getWebView().loadUrl(mUrl = url);
        else Log.w("ImprovedWebViewFragment", "WebView cannot be found. Check the view and fragment have been loaded.");
    }

    /**
     * Called when the fragment is visible to the user and actively running. Resumes the WebView.
     */
    @Override
    public void onPause() {
        super.onPause();
        mWebView.onPause();
    }

    /**
     * Called when the fragment is no longer resumed. Pauses the WebView.
     */
    @Override
    public void onResume() {
        mWebView.onResume();
        super.onResume();
    }

    /**
     * Called when the WebView has been detached from the fragment.
     * The WebView is no longer available after this time.
     */
    @Override
    public void onDestroyView() {
        mIsWebViewAvailable = false;
        super.onDestroyView();
    }

    /**
     * Called when the fragment is no longer in use. Destroys the internal state of the WebView.
     */
    @Override
    public void onDestroy() {
        if (mWebView != null) {
            mWebView.destroy();
            mWebView = null;
        }
        super.onDestroy();
    }

    /**
     * Gets the WebView.
     */
    public WebView getWebView() {
        return mIsWebViewAvailable ? mWebView : null;
    }

    /* To ensure links open within the application */
    private class InnerWebViewClient extends WebViewClient {
        @Override
        public boolean shouldOverrideUrlLoading(WebView view, String url) {
            view.loadUrl(url);
            return true;
        }


    }

希望这是有用的人的未来。

Hopefully this is useful to someone in the future.

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