我有一个Android应用，它使用标签和片段进行导航。该应用程序在启动时工作正常，但在我更改方向后，菜单项和片段中的小部件停止工作。如果我放，该应用程序可以工作
android:configChanges="orientation|screenSize"
在清单中，但在Android文档中它说这应该是最后的手段，所以我想知道是否有更好的解决方案。这是主机活动的代码和其中一个片段。
package com.mynews;
import android.app.ActionBar;
import android.app.ActionBar.Tab;
import android.app.Activity;
import android.app.Fragment;
import android.app.FragmentTransaction;
import android.os.Bundle;
import android.view.Menu;
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//setContentView(R.layout.activity_main);
//stopService(new Intent(this, FindArticlesService.class));
ActionBar actionBar = getActionBar();
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
Tab tab = actionBar.newTab()
.setText("Articles")
.setTabListener(new TabListener<Articles>(this, "articles", Articles.class));
actionBar.addTab(tab);
tab = actionBar.newTab()
.setText("Websites")
.setTabListener(new TabListener<UserSites>(this, "websites", UserSites.class));
actionBar.addTab(tab);
tab = actionBar.newTab()
.setText("Add a website")
.setTabListener(new TabListener<AddSites>(this, "add a site", AddSites.class));
actionBar.addTab(tab);
}
@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;
}
@Override
protected void onSaveInstanceState(Bundle outState) {
// TODO Auto-generated method stub
super.onSaveInstanceState(outState);
}
@Override
protected void onDestroy() {
// TODO Auto-generated method stub
super.onDestroy();
////Intent intent = new Intent(this, FindArticlesService.class);
//this.startService(intent);
}
public static class TabListener<T extends Fragment> implements ActionBar.TabListener {
Fragment fragment;
final Activity activity;
final String tag;
final Class<T> mClass;
public TabListener(Activity a, String s, Class<T> c){
activity = a;
tag = s;
mClass = c;
}
@Override
public void onTabReselected(Tab tab, FragmentTransaction ft) {
// TODO Auto-generated method stub
}
@Override
public void onTabSelected(Tab tab, FragmentTransaction ft) {
// TODO Auto-generated method stub
if(fragment == null){
fragment = Fragment.instantiate(activity, mClass.getName());
ft.add(android.R.id.content, fragment, tag);
}else{
ft.attach(fragment);
}
}
@Override
public void onTabUnselected(Tab tab, FragmentTransaction ft) {
// TODO Auto-generated method stub
if(fragment != null){
ft.detach(fragment);
}
activity.closeContextMenu();
}
}
}
My Fragment Class
package com.mynews;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.MalformedURLException;
import java.util.ArrayList;
import android.app.AlertDialog;
import android.app.Dialog;
import android.app.DialogFragment;
import android.app.Fragment;
import android.content.Context;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
public class AddSites extends Fragment {
public AddSites(){}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//setContentView(R.layout.activity_add_sites);
// Show the Up button in the action bar.
setHasOptionsMenu(true);
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onActivityCreated(savedInstanceState);
Button button = (Button) getActivity().findViewById(R.id.add);
button.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
UserSitesFunc usf = new UserSitesFunc(); //create a new UserSitesFunc to hold
try{ //the list of sites
FileInputStream fis = getActivity().openFileInput("MySites.ser");//check if there's a file
ObjectInputStream ois = new ObjectInputStream(fis);//with a USF object
usf = (UserSitesFunc) ois.readObject(); //if there is, deserialize it and use it
ois.close();//instead of a brand new object
}catch(IOException e){ //catch various exceptions
e.printStackTrace();
}catch(Exception ep){
ep.printStackTrace();
}finally{
try{ //do this with either the new object or the deserialised one
EditText website = (EditText) getActivity().findViewById(R.id.editText1);//get the input
EditText keywords = (EditText) getActivity().findViewById(R.id.editText2);//from the user
String web = website.getText().toString(); //store it in strings
String key = keywords.getText().toString();
String[] kwords = key.split(", ");
ArrayList<String> newKeywords = new ArrayList<String>();
for(String s:kwords){
newKeywords.add(s);
}
Sites s = new Sites(web, newKeywords);//create a new site from the input
if(usf.siteList.contains(s)){
showContainedDialog();
return;
}
usf.addSite(s);//add it to the user's list of sites
FileOutputStream fs = getActivity().openFileOutput("MySites.ser", Context.MODE_PRIVATE);//save it
ObjectOutputStream oos = new ObjectOutputStream(fs);
oos.writeObject(usf);
oos.close();
Toast.makeText(getActivity(), web + " added to Tracked Websites", Toast.LENGTH_LONG).show();
website.setText("");
keywords.setText("");
}catch(MalformedURLException mue){
showDialog();
}catch(Exception ex){
ex.printStackTrace();
}
}
}
});
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// TODO Auto-generated method stub
View view = inflater.inflate(R.layout.activity_add_sites, container, false);
return view;
}
@Override
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
menu.clear();
inflater.inflate(R.menu.add_sites, menu);
super.onCreateOptionsMenu(menu, inflater);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
// This ID represents the Home or Up button. In the case of this
// activity, the Up button is shown. Use NavUtils to allow users
// to navigate up one level in the application structure. For
// more details, see the Navigation pattern on Android Design:
//
// http://developer.android.com/design/patterns/navigation.html#up-vs-back
//
return true;
}
return super.onOptionsItemSelected(item);
}
public static class NotAWebsiteDialog extends DialogFragment {
public static NotAWebsiteDialog newInstance(){
NotAWebsiteDialog notAWebsite = new NotAWebsiteDialog();
Bundle args = new Bundle();
notAWebsite.setArguments(args);
return notAWebsite;
}
@Override
public Dialog onCreateDialog(final Bundle savedInstanceState) {
// TODO Auto-generated method stub
return new AlertDialog.Builder(getActivity())
.setMessage("Please enter a vaild web address")
.create();
}
}
public void showDialog(){
DialogFragment dialog = NotAWebsiteDialog.newInstance();
dialog.show(getFragmentManager(), "Not A Website");
}
public static class AlreadyContainsWebsiteDialog extends DialogFragment {
public static AlreadyContainsWebsiteDialog newInstance(){
AlreadyContainsWebsiteDialog containsAWebsite = new AlreadyContainsWebsiteDialog();
Bundle args = new Bundle();
containsAWebsite.setArguments(args);
return containsAWebsite;
}
@Override
public Dialog onCreateDialog(final Bundle savedInstanceState) {
// TODO Auto-generated method stub
return new AlertDialog.Builder(getActivity())
.setMessage("This website is already being tracked")
.create();
}
}
public void showContainedDialog(){
DialogFragment dialog = AlreadyContainsWebsiteDialog.newInstance();
dialog.show(getFragmentManager(), "Contains this Website");
}
}