带有Webview的片段利用harware后退按钮转到上一个网页 [英] Fragment with Webview utilize harware back button to go to previous webpage
本文介绍了带有Webview的片段利用harware后退按钮转到上一个网页的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
这似乎在堆栈溢出问题上被问了很多，但是随着SDK的更改，答案似乎不再可行(我可能是错的！).
This appears to have been asked a lot on stack overflow, but with answers which appear to no longer be implementable with changes to the SDK (I may be wrong!).
我一直在尝试允许MainActivity中的一个片段使用硬件按钮返回到片段中Web视图中的上一页.
I have been trying to allow a fragment inside my MainActivity to use the hardware button to go back to the previous page inside a webview in the fragment.
我已经尝试使用return super.onKeyDown(keyCode，event);作为功能的一部分，但onKeyDown在我的项目中显示为无效.
I have tried using return super.onKeyDown(keyCode, event); as part of a function but onKeyDown does not come up as valid in my project.
这是我的BlogFragment，其中包含网络视图:
This is my BlogFragment containing the webview:
public class BlogFragment extends Fragment {
// TODO: Rename parameter arguments, choose names that match
// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
private static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";
// TODO: Rename and change types of parameters
private String mParam1;
private String mParam2;
WebView wv;
private OnFragmentInteractionListener mListener;
/**
* Use this factory method to create a new instance of
* this fragment using the provided parameters.
*
* @param param1 Parameter 1.
* @param param2 Parameter 2.
* @return A new instance of fragment blog.
*/
// TODO: Rename and change types and number of parameters
public static BlogFragment newInstance(String param1, String param2) {
BlogFragment fragment = new BlogFragment();
Bundle args = new Bundle();
args.putString(ARG_PARAM1, param1);
args.putString(ARG_PARAM2, param2);
fragment.setArguments(args);
return fragment;
}
public static boolean canGoBack(){
return wv.canGoBack();
}
public static void goBack(){
wv.goBack();
}
public BlogFragment() {
// Required empty public constructor
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
mParam1 = getArguments().getString(ARG_PARAM1);
mParam2 = getArguments().getString(ARG_PARAM2);
}
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view=inflater.inflate(R.layout.fragment_blog, null);
wv = (WebView) view.findViewById(R.id.webview);
WebSettings settings = wv.getSettings();
wv.setWebChromeClient(new WebChromeClient() {
});
final String mimeType = "text/html";
final String encoding = "UTF-8";
String html = getHTML();
settings.setJavaScriptEnabled(true);
wv.loadDataWithBaseURL("http://www.bbc.co.uk", html, mimeType, encoding, "");
return view;
}
// TODO: Rename method, update argument and hook method into UI event
public void onButtonPressed(Uri uri) {
if (mListener != null) {
mListener.onFragmentInteraction(uri);
}
}
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
try {
mListener = (OnFragmentInteractionListener) activity;
} catch (ClassCastException e) {
throw new ClassCastException(activity.toString()
+ " must implement OnFragmentInteractionListener");
}
}
@Override
public void onDetach() {
super.onDetach();
mListener = null;
}
public String getHTML() {
String html = "<iframe width=\"100%\" height=\"100%\" src=\"http://blog.mrgyro.co.uk\" frameborder=\"0\" allowfullscreen></iframe>";
return html;
}
/**
* This interface must be implemented by activities that contain this
* fragment to allow an interaction in this fragment to be communicated
* to the activity and potentially other fragments contained in that
* activity.
* <p/>
* See the Android Training lesson <a href=
* "http://developer.android.com/training/basics/fragments/communicating.html"
* >Communicating with Other Fragments</a> for more information.
*/
public interface OnFragmentInteractionListener {
// TODO: Update argument type and name
public void onFragmentInteraction(Uri uri);
}
}
活动:
public class MainActivity extends ActionBarActivity
implements NavigationDrawerFragment.NavigationDrawerCallbacks, BlogFragment.OnFragmentInteractionListener, HomeFragment.OnFragmentInteractionListener {
/**
* Fragment managing the behaviors, interactions and presentation of the navigation drawer.
*/
private NavigationDrawerFragment mNavigationDrawerFragment;
/**
* Used to store the last screen title. For use in {@link #restoreActionBar()}.
*/
private CharSequence mTitle;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mNavigationDrawerFragment = (NavigationDrawerFragment)
getSupportFragmentManager().findFragmentById(R.id.navigation_drawer);
mTitle = getTitle();
// Set up the drawer.
mNavigationDrawerFragment.setUp(
R.id.navigation_drawer,
(DrawerLayout) findViewById(R.id.drawer_layout));
}
@Override
public void onBackPressed() {
if(BlogFragment.canGoBack()){
BlogFragment.goBack();
}else{
super.onBackPressed();
}
}
@Override
public void onNavigationDrawerItemSelected(int position) {
android.support.v4.app.FragmentManager fragmentManager = getSupportFragmentManager();
android.support.v4.app.FragmentTransaction transaction = fragmentManager.beginTransaction();
switch (position) {
case 0:
HomeFragment homeFragment = new HomeFragment();
transaction.replace(R.id.container, homeFragment);
break;
case 1:
BlogFragment blogFragment = new BlogFragment();
transaction.replace(R.id.container, blogFragment);
break;
}
transaction.commit();
}
public void onSectionAttached(int number) {
switch (number) {
case 1:
mTitle = getString(R.string.title_section1);
break;
case 2:
mTitle = getString(R.string.title_section2);
break;
case 3:
mTitle = getString(R.string.title_section3);
break;
case 4:
mTitle = getString(R.string.title_section4);
break;
}
}
public void restoreActionBar() {
ActionBar actionBar = getSupportActionBar();
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_STANDARD);
actionBar.setDisplayShowTitleEnabled(true);
actionBar.setTitle(mTitle);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
if (!mNavigationDrawerFragment.isDrawerOpen()) {
// Only show items in the action bar relevant to this screen
// if the drawer is not showing. Otherwise, let the drawer
// decide what to show in the action bar.
getMenuInflater().inflate(R.menu.main, menu);
restoreActionBar();
return true;
}
return super.onCreateOptionsMenu(menu);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
//if (id == R.id.action_settings) {
// return true;
// }
return super.onOptionsItemSelected(item);
}
@Override
public void onFragmentInteraction(Uri uri) {
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
/**
* The fragment argument representing the section number for this
* fragment.
*/
private static final String ARG_SECTION_NUMBER = "section_number";
/**
* Returns a new instance of this fragment for the given section
* number.
*/
public static PlaceholderFragment newInstance(int sectionNumber) {
PlaceholderFragment fragment = new PlaceholderFragment();
Bundle args = new Bundle();
args.putInt(ARG_SECTION_NUMBER, sectionNumber);
fragment.setArguments(args);
return fragment;
}
public PlaceholderFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = null;
rootView = inflater.inflate(R.layout.fragment_home, container, false);
switch(getArguments().getInt(ARG_SECTION_NUMBER)) {
case 1:
rootView = inflater.inflate(R.layout.fragment_home, container, false);
break;
case 2:
rootView = inflater.inflate(R.layout.fragment_blog, container, false);
break;
case 3:
// rootView = inflater.inflate(R.layout.fragment_test, container, false);
break;
case 4:
//rootView = inflater.inflate(R.layout.fragment_info, container, false);
break;
default:
Log.e("TAG", "Unrecognized section: " + getArguments().getInt(ARG_SECTION_NUMBER));
}
return rootView;
}
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
((MainActivity) activity).onSectionAttached(
getArguments().getInt(ARG_SECTION_NUMBER));
}
}
}
谢谢.
我已经用最近的尝试更新了博客片段，但是当尝试静态wv.canGoBack()和wv.goBack()都返回错误非静态字段'wv'不能从静态上下文
I have updated the blog fragment with my most recent attempt, however when trying to static wv.canGoBack() and wv.goBack() both return the error "Non-Static field 'wv' cannot be referenced from a static context
推荐答案
尝试覆盖 onBackPressed()在您的 Activity 中，并使其戳 WebView .
Try overriding onBackPressed() in your Activity and make it poke the WebView.
顺便说一句-您也可以发布包含 onKeyDown 方法的 Activity 片段.
BTW - you could post the piece of Activity containing the onKeyDown method as well.
首先实例化片段:
BlogFragment blogFragment = new BlogFragment();
blogFragment.canGoBack();
，然后从您的方法中删除 static .:)
and then just remove the static from your methods. :)
OP的实现(感谢Klotor)在MainActivity工具的顶部:
OPs implementation (with thanks to Klotor) At the head of MainActivity implement:
BlogFragment blogFragment = new BlogFragment();
然后执行:
public void onBackPressed() {
blogFragment.canGoBack();
if(blogFragment.canGoBack()){
blogFragment.goBack();
}else{
super.onBackPressed();
}
}
为了避免在使用片段之间导航的方法时崩溃，片段是在onBackPressed外部实例化的.在这种情况下，您需要实例化该片段的新实例，而不是实例化整个新片段.
The fragment is instantiated outside of the onBackPressed in order to prevent crashing when using a method to navigate between fragments. In this case you need to instantiate a newinstance of the fragment, rather than a whole new fragment.
这篇关于带有Webview的片段利用harware后退按钮转到上一个网页的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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