发现问题：
行为是由于遗留了一些库项目导入造成的。特别是ActionBarSherlock和SlidingMenuLibrary，两者都没有被使用。
奇怪的问题。
FragmentStatePagerAdapter似乎在实例化每个片段，然后在页面滑动中销毁它们。 （即实例化所有100个碎片，并摧毁不需要的97个碎片） 只是看看之前是否有人见过这些症状？
刚刚通过多次调用getView调试ListView layout problems我认为这里可能有类似的东西？ 在我开始正确调试之前，任何人都有一些快速的想法吗？
感谢
更新。 附上我试图做的简单工作版本......所以它表明它是可行的。 现在只需要调试我的主要代码的笨重版本:-( 一定做了些蠢事。
public class MainActivity extends FragmentActivity {
private DrawerLayout mDrawerLayout;
private ListView mDrawerList;
private ActionBarDrawerToggle mDrawerToggle;
private CharSequence mDrawerTitle;
private CharSequence mTitle;
private String[] mPlanetTitles;
private ViewPager mViewPager;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mTitle = mDrawerTitle = getTitle();
mPlanetTitles = getResources().getStringArray(R.array.planets_array);
mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
mDrawerList = (ListView) findViewById(R.id.left_drawer);
// set a custom shadow that overlays the main content when the drawer opens
mDrawerLayout.setDrawerShadow(R.drawable.drawer_shadow, GravityCompat.START);
// set up the drawer's list view with items and click listener
mDrawerList.setAdapter(new ArrayAdapter<String>(this,
R.layout.drawer_list_item, mPlanetTitles));
mDrawerList.setOnItemClickListener(new DrawerItemClickListener());
// enable ActionBar app icon to behave as action to toggle nav drawer
getActionBar().setDisplayHomeAsUpEnabled(true);
getActionBar().setHomeButtonEnabled(true);
// ActionBarDrawerToggle ties together the the proper interactions
// between the sliding drawer and the action bar app icon
mDrawerToggle = new ActionBarDrawerToggle(
this, /* host Activity */
mDrawerLayout, /* DrawerLayout object */
R.drawable.ic_drawer, /* nav drawer image to replace 'Up' caret */
R.string.drawer_open, /* "open drawer" description for accessibility */
R.string.drawer_close /* "close drawer" description for accessibility */
) {
public void onDrawerClosed(View view) {
getActionBar().setTitle(mTitle);
invalidateOptionsMenu(); // creates call to onPrepareOptionsMenu()
}
public void onDrawerOpened(View drawerView) {
getActionBar().setTitle(mDrawerTitle);
invalidateOptionsMenu(); // creates call to onPrepareOptionsMenu()
}
};
mDrawerLayout.setDrawerListener(mDrawerToggle);
// and now setup the viewpager
mViewPager = (ViewPager)findViewById(R.id.view_pager);
mViewPager.setAdapter(new ContentPagerAdapter(getSupportFragmentManager()));
// sets up the lhs and rhs fragments
if (savedInstanceState == null) {
selectItem(0);
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.main, menu);
return super.onCreateOptionsMenu(menu);
}
/* Called whenever we call invalidateOptionsMenu() */
@Override
public boolean onPrepareOptionsMenu(Menu menu) {
// If the nav drawer is open, hide action items related to the content view
boolean drawerOpen = mDrawerLayout.isDrawerOpen(mDrawerList);
menu.findItem(R.id.action_websearch).setVisible(!drawerOpen);
return super.onPrepareOptionsMenu(menu);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// The action bar home/up action should open or close the drawer.
// ActionBarDrawerToggle will take care of this.
if (mDrawerToggle.onOptionsItemSelected(item)) {
return true;
}
// Handle action buttons
switch(item.getItemId()) {
case R.id.action_websearch:
// create intent to perform web search for this planet
Intent intent = new Intent(Intent.ACTION_WEB_SEARCH);
intent.putExtra(SearchManager.QUERY, getActionBar().getTitle());
// catch event that there's no activity to handle intent
if (intent.resolveActivity(getPackageManager()) != null) {
startActivity(intent);
} else {
Toast.makeText(this, R.string.app_not_available, Toast.LENGTH_LONG).show();
}
return true;
default:
return super.onOptionsItemSelected(item);
}
}
/* The click listner for ListView in the navigation drawer */
private class DrawerItemClickListener implements ListView.OnItemClickListener {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
selectItem(position);
}
}
private void selectItem(int position) {
// update the main content by replacing fragments
// create the lhs and rhs fragments
Fragment lhsFragment = new PlaceHolderFragment();
Bundle args = new Bundle();
args.putString(PlaceHolderFragment.FRAGMENT_TEXT_KEY, mPlanetTitles[position]);
lhsFragment.setArguments(args);
Fragment rhsFragment = new PlaceHolderFragment();
args = new Bundle();
args.putString(PlaceHolderFragment.FRAGMENT_TEXT_KEY, mPlanetTitles[position]);
rhsFragment.setArguments(args);
FragmentManager fragmentManager = getSupportFragmentManager();
FragmentTransaction ft = fragmentManager.beginTransaction().replace(R.id.lhs_fragment, lhsFragment);
ft.replace(R.id.rhs_fragment, rhsFragment);
ft.commit();
// update selected item and title, then close the drawer
mDrawerList.setItemChecked(position, true);
setTitle(mPlanetTitles[position]);
mDrawerLayout.closeDrawer(mDrawerList);
// and smooth scroll the viewpager
mViewPager.setCurrentItem(position, true);
}
@Override
public void setTitle(CharSequence title) {
mTitle = title;
getActionBar().setTitle(mTitle);
}
/**
* When using the ActionBarDrawerToggle, you must call it during
* onPostCreate() and onConfigurationChanged()...
*/
@Override
protected void onPostCreate(Bundle savedInstanceState) {
super.onPostCreate(savedInstanceState);
// Sync the toggle state after onRestoreInstanceState has occurred.
mDrawerToggle.syncState();
}
@Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
// Pass any configuration change to the drawer toggls
mDrawerToggle.onConfigurationChanged(newConfig);
}
/**
* Fragment that appears in the "content_frame", shows a planet
*/
public static class PlanetFragment extends Fragment {
public static final String ARG_PLANET_NUMBER = "planet_number";
public PlanetFragment() {
// Empty constructor required for fragment subclasses
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_planet, container, false);
int i = getArguments().getInt(ARG_PLANET_NUMBER);
String planet = getResources().getStringArray(R.array.planets_array)[i];
int imageId = getResources().getIdentifier(planet.toLowerCase(Locale.getDefault()),
"drawable", getActivity().getPackageName());
((ImageView) rootView.findViewById(R.id.image)).setImageResource(imageId);
getActivity().setTitle(planet);
return rootView;
}
}
/**
* Simple Place Holder Fragment...
*/
public static class PlaceHolderFragment extends Fragment {
public static final String FRAGMENT_TEXT_KEY = "text_key";
public PlaceHolderFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.place_holder_layout, container, false);
String text = getArguments().getString(FRAGMENT_TEXT_KEY);
((TextView)rootView.findViewById(R.id.place_holder_text)).setText(text);
return rootView;
}
}
/**
* FragmentStatePagerAdapter for delivering up the planets for the ViewPAger
*/
private class ContentPagerAdapter extends FragmentStatePagerAdapter {
int mCount;
public ContentPagerAdapter(FragmentManager fm) {
super(fm);
mCount = getResources().getStringArray(R.array.planets_array).length;
}
@Override
public Fragment getItem(int position) {
Log.d("ContentPagerAdapter", "getItem() position: " + position + " called.");
Fragment fragment = new PlanetFragment();
Bundle args = new Bundle();
args.putInt(PlanetFragment.ARG_PLANET_NUMBER, position);
fragment.setArguments(args);
return fragment;
}
@Override
public int getCount() {
return mCount;
}
}
}
主要布局
<android.support.v4.widget.DrawerLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent">
<!-- As the main content view, the view below consumes the entire
space available using match_parent in both dimensions. -->
<include layout="@layout/content_frames_layout" />
<!-- android:layout_gravity="start" tells DrawerLayout to treat
this as a sliding drawer on the left side for left-to-right
languages and on the right side for right-to-left languages.
The drawer is given a fixed width in dp and extends the full height of
the container. A solid background is used for contrast
with the content view. -->
<ListView
android:id="@+id/left_drawer"
android:layout_width="240dp"
android:layout_height="match_parent"
android:layout_gravity="start"
android:choiceMode="singleChoice"
android:divider="@android:color/transparent"
android:dividerHeight="0dp"
android:background="#111"/>
</android.support.v4.widget.DrawerLayout>
和content_frames_layout
<!-- RelativeLayout holds the various fragments / ViewPager that hold the content -->
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal" >
<!-- Simple left hand side fragment -->
<FrameLayout
android:id="@+id/lhs_fragment"
android:layout_height="match_parent"
android:layout_width="0px"
android:layout_weight="1" />
<!-- The main view pager -->
<android.support.v4.view.ViewPager
android:id="@+id/view_pager"
android:layout_height="match_parent"
android:layout_width="0px"
android:layout_weight="3" >
</android.support.v4.view.ViewPager>
<!-- simple rhs fragment -->
<FrameLayout
android:id="@+id/rhs_fragment"
android:layout_height="match_parent"
android:layout_width="0px"
android:layout_weight="1" />
</LinearLayout>
答案 0 :(得分：0)
我得到了这种行为，它让我疯狂，直到我发现：
视图寻呼机元素必须具有固定宽度
在我的情况下，我有这个双窗格布局（左边的菜单，右边的viewpager）：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:animateLayoutChanges="true">
<fragment android:name="com.vitasalutis.client.main.ParameterMenuFragment"
android:id="@+id/parameter_menu_fragment"
android:layout_weight="1"
android:layout_width="0dp"
android:layout_height="match_parent" />
<android.support.v4.view.ViewPager
android:id="@+id/parameter_pager"
android:layout_weight="2"
android:layout_width="0dp"
android:layout_height="match_parent"
android:visibility="gone"
/>
</LinearLayout>
必须将ViewPager的宽度更改为：
android:layout_width="600dp"
我的猜测是，没有固定的宽度，它无法确定布局中适合的页数。我试图覆盖getPageWidth(int)以始终返回1，并且也无效...
我不知道是否有更好的方法来做到这一点。同时，我会坚持这个解决方案。