我试图使用片段与一个ViewPager使用FragmentPagerAdapter。
我想要实现的是替换一个片段，位于ViewPager的第一页，与另一个。
寻呼机由两个页面组成。第一个是FirstPagerFragment，第二个是SecondPagerFragment。点击第一页的一个按钮。我想用NextFragment替换FirstPagerFragment。
下面是我的代码。
public class FragmentPagerActivity extends FragmentActivity {
static final int NUM_ITEMS = 2;
MyAdapter mAdapter;
ViewPager mPager;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.fragment_pager);
mAdapter = new MyAdapter(getSupportFragmentManager());
mPager = (ViewPager) findViewById(R.id.pager);
mPager.setAdapter(mAdapter);
}
/**
* Pager Adapter
*/
public static class MyAdapter extends FragmentPagerAdapter {
public MyAdapter(FragmentManager fm) {
super(fm);
}
@Override
public int getCount() {
return NUM_ITEMS;
}
@Override
public Fragment getItem(int position) {
if(position == 0) {
return FirstPageFragment.newInstance();
} else {
return SecondPageFragment.newInstance();
}
}
}
/**
* Second Page FRAGMENT
*/
public static class SecondPageFragment extends Fragment {
public static SecondPageFragment newInstance() {
SecondPageFragment f = new SecondPageFragment();
return f;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
//Log.d("DEBUG", "onCreateView");
return inflater.inflate(R.layout.second, container, false);
}
}
/**
* FIRST PAGE FRAGMENT
*/
public static class FirstPageFragment extends Fragment {
Button button;
public static FirstPageFragment newInstance() {
FirstPageFragment f = new FirstPageFragment();
return f;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
//Log.d("DEBUG", "onCreateView");
View root = inflater.inflate(R.layout.first, container, false);
button = (Button) root.findViewById(R.id.button);
button.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
FragmentTransaction trans = getFragmentManager().beginTransaction();
trans.replace(R.id.first_fragment_root_id, NextFragment.newInstance());
trans.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
trans.addToBackStack(null);
trans.commit();
}
});
return root;
}
/**
* Next Page FRAGMENT in the First Page
*/
public static class NextFragment extends Fragment {
public static NextFragment newInstance() {
NextFragment f = new NextFragment();
return f;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
//Log.d("DEBUG", "onCreateView");
return inflater.inflate(R.layout.next, container, false);
}
}
}
.．.这里是XML文件
fragment_pager.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:padding="4dip"
android:gravity="center_horizontal"
android:layout_width="match_parent" android:layout_height="match_parent">
<android.support.v4.view.ViewPager
android:id="@+id/pager"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="1">
</android.support.v4.view.ViewPager>
</LinearLayout>
first.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/first_fragment_root_id"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<Button android:id="@+id/button"
android:layout_width="wrap_content" android:layout_height="wrap_content"
android:text="to next"/>
</LinearLayout>
现在的问题是……我应该使用哪个ID
trans.replace(R.id.first_fragment_root_id, NextFragment.newInstance());
?
如果我用r。id。first_fragment_root_id，替换工作，但Hierarchy Viewer显示一个奇怪的行为，如下所示。
一开始的情况是
更换后的情况是
正如你所看到的，有一些错误，我希望在替换片段后找到与第一张图片中相同的状态。
Works Great with AndroidTeam's solution, however I found that I needed the ability to go back much like FrgmentTransaction.addToBackStack(null) But merely adding this will only cause the Fragment to be replaced without notifying the ViewPager. Combining the provided solution with this minor enhancement will allow you to return to the previous state by merely overriding the activity's onBackPressed() method. The biggest drawback is that it will only go back one at a time which may result in multiple back clicks
private ArrayList<Fragment> bFragments = new ArrayList<Fragment>();
private ArrayList<Integer> bPosition = new ArrayList<Integer>();
public void replaceFragmentsWithBackOut(ViewPager container, Fragment oldFragment, Fragment newFragment) {
startUpdate(container);
// remove old fragment
if (mCurTransaction == null) {
mCurTransaction = mFragmentManager.beginTransaction();
}
int position = getFragmentPosition(oldFragment);
while (mSavedState.size() <= position) {
mSavedState.add(null);
}
//Add Fragment to Back List
bFragments.add(oldFragment);
//Add Pager Position to Back List
bPosition.add(position);
mSavedState.set(position, null);
mFragments.set(position, null);
mCurTransaction.remove(oldFragment);
// add new fragment
while (mFragments.size() <= position) {
mFragments.add(null);
}
mFragments.set(position, newFragment);
mCurTransaction.add(container.getId(), newFragment);
finishUpdate(container);
// ensure getItem returns newFragemtn after calling handleGetItemInbalidated()
handleGetItemInvalidated(container, oldFragment, newFragment);
container.notifyItemChanged(oldFragment, newFragment);
}
public boolean popBackImmediate(ViewPager container){
int bFragSize = bFragments.size();
int bPosSize = bPosition.size();
if(bFragSize>0 && bPosSize>0){
if(bFragSize==bPosSize){
int last = bFragSize-1;
int position = bPosition.get(last);
//Returns Fragment Currently at this position
Fragment replacedFragment = mFragments.get(position);
Fragment originalFragment = bFragments.get(last);
this.replaceFragments(container, replacedFragment, originalFragment);
bPosition.remove(last);
bFragments.remove(last);
return true;
}
}
return false;
}
希望这能帮助到一些人。
同样，就getFragmentPosition()而言，它几乎是反向的getItem()。你知道哪些片段去哪里，只是确保你返回正确的位置它将在。这里有一个例子:
@Override
protected int getFragmentPosition(Fragment fragment) {
if(fragment.equals(originalFragment1)){
return 0;
}
if(fragment.equals(replacementFragment1)){
return 0;
}
if(fragment.equals(Fragment2)){
return 1;
}
return -1;
}
我已经实现了一个解决方案:
标签内的动态片段替换
维护每个选项卡的历史记录
处理方向变化
实现这一目标的技巧如下:
使用notifyDataSetChanged()方法来应用片段替换
片段管理器只用于后台，而不用于片段替换
使用纪念品模式(堆栈)维护历史记录
适配器代码如下:
public class TabsAdapter extends FragmentStatePagerAdapter implements ActionBar.TabListener, ViewPager.OnPageChangeListener {
/** The sherlock fragment activity. */
private final SherlockFragmentActivity mActivity;
/** The action bar. */
private final ActionBar mActionBar;
/** The pager. */
private final ViewPager mPager;
/** The tabs. */
private List<TabInfo> mTabs = new LinkedList<TabInfo>();
/** The total number of tabs. */
private int TOTAL_TABS;
private Map<Integer, Stack<TabInfo>> history = new HashMap<Integer, Stack<TabInfo>>();
/**
* Creates a new instance.
*
* @param activity the activity
* @param pager the pager
*/
public TabsAdapter(SherlockFragmentActivity activity, ViewPager pager) {
super(activity.getSupportFragmentManager());
activity.getSupportFragmentManager();
this.mActivity = activity;
this.mActionBar = activity.getSupportActionBar();
this.mPager = pager;
mActionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
}
/**
* Adds the tab.
*
* @param image the image
* @param fragmentClass the class
* @param args the arguments
*/
public void addTab(final Drawable image, final Class fragmentClass, final Bundle args) {
final TabInfo tabInfo = new TabInfo(fragmentClass, args);
final ActionBar.Tab tab = mActionBar.newTab();
tab.setTabListener(this);
tab.setTag(tabInfo);
tab.setIcon(image);
mTabs.add(tabInfo);
mActionBar.addTab(tab);
notifyDataSetChanged();
}
@Override
public Fragment getItem(final int position) {
final TabInfo tabInfo = mTabs.get(position);
return Fragment.instantiate(mActivity, tabInfo.fragmentClass.getName(), tabInfo.args);
}
@Override
public int getItemPosition(final Object object) {
/* Get the current position. */
int position = mActionBar.getSelectedTab().getPosition();
/* The default value. */
int pos = POSITION_NONE;
if (history.get(position).isEmpty()) {
return POSITION_NONE;
}
/* Checks if the object exists in current history. */
for (Stack<TabInfo> stack : history.values()) {
TabInfo c = stack.peek();
if (c.fragmentClass.getName().equals(object.getClass().getName())) {
pos = POSITION_UNCHANGED;
break;
}
}
return pos;
}
@Override
public int getCount() {
return mTabs.size();
}
@Override
public void onPageScrollStateChanged(int arg0) {
}
@Override
public void onPageScrolled(int arg0, float arg1, int arg2) {
}
@Override
public void onPageSelected(int position) {
mActionBar.setSelectedNavigationItem(position);
}
@Override
public void onTabSelected(final ActionBar.Tab tab, final FragmentTransaction ft) {
TabInfo tabInfo = (TabInfo) tab.getTag();
for (int i = 0; i < mTabs.size(); i++) {
if (mTabs.get(i).equals(tabInfo)) {
mPager.setCurrentItem(i);
}
}
}
@Override
public void onTabUnselected(ActionBar.Tab tab, FragmentTransaction ft) {
}
@Override
public void onTabReselected(ActionBar.Tab tab, FragmentTransaction ft) {
}
public void replace(final int position, final Class fragmentClass, final Bundle args) {
/* Save the fragment to the history. */
mActivity.getSupportFragmentManager().beginTransaction().addToBackStack(null).commit();
/* Update the tabs. */
updateTabs(new TabInfo(fragmentClass, args), position);
/* Updates the history. */
history.get(position).push(new TabInfo(mTabs.get(position).fragmentClass, mTabs.get(position).args));
notifyDataSetChanged();
}
/**
* Updates the tabs.
*
* @param tabInfo
* the new tab info
* @param position
* the position
*/
private void updateTabs(final TabInfo tabInfo, final int position) {
mTabs.remove(position);
mTabs.add(position, tabInfo);
mActionBar.getTabAt(position).setTag(tabInfo);
}
/**
* Creates the history using the current state.
*/
public void createHistory() {
int position = 0;
TOTAL_TABS = mTabs.size();
for (TabInfo mTab : mTabs) {
if (history.get(position) == null) {
history.put(position, new Stack<TabInfo>());
}
history.get(position).push(new TabInfo(mTab.fragmentClass, mTab.args));
position++;
}
}
/**
* Called on back
*/
public void back() {
int position = mActionBar.getSelectedTab().getPosition();
if (!historyIsEmpty(position)) {
/* In case there is not any other item in the history, then finalize the activity. */
if (isLastItemInHistory(position)) {
mActivity.finish();
}
final TabInfo currentTabInfo = getPrevious(position);
mTabs.clear();
for (int i = 0; i < TOTAL_TABS; i++) {
if (i == position) {
mTabs.add(new TabInfo(currentTabInfo.fragmentClass, currentTabInfo.args));
} else {
TabInfo otherTabInfo = history.get(i).peek();
mTabs.add(new TabInfo(otherTabInfo.fragmentClass, otherTabInfo.args));
}
}
}
mActionBar.selectTab(mActionBar.getTabAt(position));
notifyDataSetChanged();
}
/**
* Returns if the history is empty.
*
* @param position
* the position
* @return the flag if empty
*/
private boolean historyIsEmpty(final int position) {
return history == null || history.isEmpty() || history.get(position).isEmpty();
}
private boolean isLastItemInHistory(final int position) {
return history.get(position).size() == 1;
}
/**
* Returns the previous state by the position provided.
*
* @param position
* the position
* @return the tab info
*/
private TabInfo getPrevious(final int position) {
TabInfo currentTabInfo = history.get(position).pop();
if (!history.get(position).isEmpty()) {
currentTabInfo = history.get(position).peek();
}
return currentTabInfo;
}
/** The tab info class */
private static class TabInfo {
/** The fragment class. */
public Class fragmentClass;
/** The args.*/
public Bundle args;
/**
* Creates a new instance.
*
* @param fragmentClass
* the fragment class
* @param args
* the args
*/
public TabInfo(Class fragmentClass, Bundle args) {
this.fragmentClass = fragmentClass;
this.args = args;
}
@Override
public boolean equals(final Object o) {
return this.fragmentClass.getName().equals(o.getClass().getName());
}
@Override
public int hashCode() {
return fragmentClass.getName() != null ? fragmentClass.getName().hashCode() : 0;
}
@Override
public String toString() {
return "TabInfo{" +
"fragmentClass=" + fragmentClass +
'}';
}
}
第一次添加所有选项卡时，我们需要调用createHistory()方法来创建初始历史记录
public void createHistory() {
int position = 0;
TOTAL_TABS = mTabs.size();
for (TabInfo mTab : mTabs) {
if (history.get(position) == null) {
history.put(position, new Stack<TabInfo>());
}
history.get(position).push(new TabInfo(mTab.fragmentClass, mTab.args));
position++;
}
}
每次你想要替换一个片段到一个特定的标签，你调用:
replace(final int position, final Class fragmentClass, final Bundle args)
/* Save the fragment to the history. */
mActivity.getSupportFragmentManager().beginTransaction().addToBackStack(null).commit();
/* Update the tabs. */
updateTabs(new TabInfo(fragmentClass, args), position);
/* Updates the history. */
history.get(position).push(new TabInfo(mTabs.get(position).fragmentClass, mTabs.get(position).args));
notifyDataSetChanged();
在back被按下时，你需要调用back()方法:
public void back() {
int position = mActionBar.getSelectedTab().getPosition();
if (!historyIsEmpty(position)) {
/* In case there is not any other item in the history, then finalize the activity. */
if (isLastItemInHistory(position)) {
mActivity.finish();
}
final TabInfo currentTabInfo = getPrevious(position);
mTabs.clear();
for (int i = 0; i < TOTAL_TABS; i++) {
if (i == position) {
mTabs.add(new TabInfo(currentTabInfo.fragmentClass, currentTabInfo.args));
} else {
TabInfo otherTabInfo = history.get(i).peek();
mTabs.add(new TabInfo(otherTabInfo.fragmentClass, otherTabInfo.args));
}
}
}
mActionBar.selectTab(mActionBar.getTabAt(position));
notifyDataSetChanged();
}
解决方案与夏洛克动作栏和滑动手势。
我按照@wize和@mdelolmo的答案，我得到了解决方案。由于吨。但是，我稍微调整了这些解决方案，以提高内存消耗。
我观察到的问题:
它们保存被替换的Fragment实例。在我的情况下，它是一个持有MapView的片段，我认为它的成本很高。所以，我维护FragmentPagerPositionChanged (POSITION_NONE或POSITION_UNCHANGED)而不是Fragment本身。
这是我的实现。
public static class DemoCollectionPagerAdapter extends FragmentStatePagerAdapter {
private SwitchFragListener mSwitchFragListener;
private Switch mToggle;
private int pagerAdapterPosChanged = POSITION_UNCHANGED;
private static final int TOGGLE_ENABLE_POS = 2;
public DemoCollectionPagerAdapter(FragmentManager fm, Switch toggle) {
super(fm);
mToggle = toggle;
mSwitchFragListener = new SwitchFragListener();
mToggle.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
mSwitchFragListener.onSwitchToNextFragment();
}
});
}
@Override
public Fragment getItem(int i) {
switch (i)
{
case TOGGLE_ENABLE_POS:
if(mToggle.isChecked())
{
return TabReplaceFragment.getInstance();
}else
{
return DemoTab2Fragment.getInstance(i);
}
default:
return DemoTabFragment.getInstance(i);
}
}
@Override
public int getCount() {
return 5;
}
@Override
public CharSequence getPageTitle(int position) {
return "Tab " + (position + 1);
}
@Override
public int getItemPosition(Object object) {
// This check make sures getItem() is called only for the required Fragment
if (object instanceof TabReplaceFragment
|| object instanceof DemoTab2Fragment)
return pagerAdapterPosChanged;
return POSITION_UNCHANGED;
}
/**
* Switch fragments Interface implementation
*/
private final class SwitchFragListener implements
SwitchFragInterface {
SwitchFragListener() {}
public void onSwitchToNextFragment() {
pagerAdapterPosChanged = POSITION_NONE;
notifyDataSetChanged();
}
}
/**
* Interface to switch frags
*/
private interface SwitchFragInterface{
void onSwitchToNextFragment();
}
}
演示链接在这里..https://youtu.be/l_62uhKkLyM
出于演示目的，在位置2处使用了两个片段TabReplaceFragment和DemoTab2Fragment。在所有其他情况下，我使用DemoTabFragment实例。
解释:
我将Switch从Activity传递到DemoCollectionPagerAdapter。基于这个开关的状态，我们将显示正确的片段。当开关检查被更改时，我调用SwitchFragListener的onSwitchToNextFragment方法，其中我将pagerAdapterPosChanged变量的值更改为POSITION_NONE。查看更多关于POSITION_NONE的信息。这将使getItem无效，我有逻辑实例化正确的片段在那里。抱歉，如果解释得有点乱的话。
再次感谢@wize和@mdelolmo的原创想法。
希望这对你有帮助。：）
如果这个实现有任何缺陷，请告诉我。那将对我的项目大有帮助。
我也做了一个解决方案，那就是与Stacks合作。这是一种更模块化的方法，所以你不必在FragmentPagerAdapter中指定每个Fragment和Detail Fragment。它建立在ActionbarSherlock的示例之上，如果我是对的，它来自谷歌演示应用程序。
/**
* This is a helper class that implements the management of tabs and all
* details of connecting a ViewPager with associated TabHost. It relies on a
* trick. Normally a tab host has a simple API for supplying a View or
* Intent that each tab will show. This is not sufficient for switching
* between pages. So instead we make the content part of the tab host
* 0dp high (it is not shown) and the TabsAdapter supplies its own dummy
* view to show as the tab content. It listens to changes in tabs, and takes
* care of switch to the correct paged in the ViewPager whenever the selected
* tab changes.
*
* Changed to support more Layers of fragments on each Tab.
* by sebnapi (2012)
*
*/
public class TabsAdapter extends FragmentPagerAdapter
implements TabHost.OnTabChangeListener, ViewPager.OnPageChangeListener {
private final Context mContext;
private final TabHost mTabHost;
private final ViewPager mViewPager;
private ArrayList<String> mTabTags = new ArrayList<String>();
private HashMap<String, Stack<TabInfo>> mTabStackMap = new HashMap<String, Stack<TabInfo>>();
static final class TabInfo {
public final String tag;
public final Class<?> clss;
public Bundle args;
TabInfo(String _tag, Class<?> _class, Bundle _args) {
tag = _tag;
clss = _class;
args = _args;
}
}
static class DummyTabFactory implements TabHost.TabContentFactory {
private final Context mContext;
public DummyTabFactory(Context context) {
mContext = context;
}
@Override
public View createTabContent(String tag) {
View v = new View(mContext);
v.setMinimumWidth(0);
v.setMinimumHeight(0);
return v;
}
}
public interface SaveStateBundle{
public Bundle onRemoveFragment(Bundle outState);
}
public TabsAdapter(FragmentActivity activity, TabHost tabHost, ViewPager pager) {
super(activity.getSupportFragmentManager());
mContext = activity;
mTabHost = tabHost;
mViewPager = pager;
mTabHost.setOnTabChangedListener(this);
mViewPager.setAdapter(this);
mViewPager.setOnPageChangeListener(this);
}
/**
* Add a Tab which will have Fragment Stack. Add Fragments on this Stack by using
* addFragment(FragmentManager fm, String _tag, Class<?> _class, Bundle _args)
* The Stack will hold always the default Fragment u add here.
*
* DON'T ADD Tabs with same tag, it's not beeing checked and results in unexpected
* beahvior.
*
* @param tabSpec
* @param clss
* @param args
*/
public void addTab(TabHost.TabSpec tabSpec, Class<?> clss, Bundle args){
Stack<TabInfo> tabStack = new Stack<TabInfo>();
tabSpec.setContent(new DummyTabFactory(mContext));
mTabHost.addTab(tabSpec);
String tag = tabSpec.getTag();
TabInfo info = new TabInfo(tag, clss, args);
mTabTags.add(tag); // to know the position of the tab tag
tabStack.add(info);
mTabStackMap.put(tag, tabStack);
notifyDataSetChanged();
}
/**
* Will add the Fragment to Tab with the Tag _tag. Provide the Class of the Fragment
* it will be instantiated by this object. Proivde _args for your Fragment.
*
* @param fm
* @param _tag
* @param _class
* @param _args
*/
public void addFragment(FragmentManager fm, String _tag, Class<?> _class, Bundle _args){
TabInfo info = new TabInfo(_tag, _class, _args);
Stack<TabInfo> tabStack = mTabStackMap.get(_tag);
Fragment frag = fm.findFragmentByTag("android:switcher:" + mViewPager.getId() + ":" + mTabTags.indexOf(_tag));
if(frag instanceof SaveStateBundle){
Bundle b = new Bundle();
((SaveStateBundle) frag).onRemoveFragment(b);
tabStack.peek().args = b;
}
tabStack.add(info);
FragmentTransaction ft = fm.beginTransaction();
ft.remove(frag).commit();
notifyDataSetChanged();
}
/**
* Will pop the Fragment added to the Tab with the Tag _tag
*
* @param fm
* @param _tag
* @return
*/
public boolean popFragment(FragmentManager fm, String _tag){
Stack<TabInfo> tabStack = mTabStackMap.get(_tag);
if(tabStack.size()>1){
tabStack.pop();
Fragment frag = fm.findFragmentByTag("android:switcher:" + mViewPager.getId() + ":" + mTabTags.indexOf(_tag));
FragmentTransaction ft = fm.beginTransaction();
ft.remove(frag).commit();
notifyDataSetChanged();
return true;
}
return false;
}
public boolean back(FragmentManager fm) {
int position = mViewPager.getCurrentItem();
return popFragment(fm, mTabTags.get(position));
}
@Override
public int getCount() {
return mTabStackMap.size();
}
@Override
public int getItemPosition(Object object) {
ArrayList<Class<?>> positionNoneHack = new ArrayList<Class<?>>();
for(Stack<TabInfo> tabStack: mTabStackMap.values()){
positionNoneHack.add(tabStack.peek().clss);
} // if the object class lies on top of our stacks, we return default
if(positionNoneHack.contains(object.getClass())){
return POSITION_UNCHANGED;
}
return POSITION_NONE;
}
@Override
public Fragment getItem(int position) {
Stack<TabInfo> tabStack = mTabStackMap.get(mTabTags.get(position));
TabInfo info = tabStack.peek();
return Fragment.instantiate(mContext, info.clss.getName(), info.args);
}
@Override
public void onTabChanged(String tabId) {
int position = mTabHost.getCurrentTab();
mViewPager.setCurrentItem(position);
}
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
@Override
public void onPageSelected(int position) {
// Unfortunately when TabHost changes the current tab, it kindly
// also takes care of putting focus on it when not in touch mode.
// The jerk.
// This hack tries to prevent this from pulling focus out of our
// ViewPager.
TabWidget widget = mTabHost.getTabWidget();
int oldFocusability = widget.getDescendantFocusability();
widget.setDescendantFocusability(ViewGroup.FOCUS_BLOCK_DESCENDANTS);
mTabHost.setCurrentTab(position);
widget.setDescendantFocusability(oldFocusability);
}
@Override
public void onPageScrollStateChanged(int state) {
}
}
在MainActivity中添加后退按钮功能:
@Override
public void onBackPressed() {
if (!mTabsAdapter.back(getSupportFragmentManager())) {
super.onBackPressed();
}
}
如果你想保存碎片状态，当它被删除。让你的Fragment实现接口SaveStateBundle在函数中返回一个带有你保存状态的bundle。通过this.getArguments()获得实例化后的bundle。
你可以这样实例化一个标签:
mTabsAdapter.addTab(mTabHost.newTabSpec("firstTabTag").setIndicator("First Tab Title"),
FirstFragmentActivity.FirstFragmentFragment.class, null);
工作类似，如果你想添加一个片段在标签堆栈的顶部。
重要:我认为，如果你想在两个tab上有两个相同类的实例，这是行不通的。
我在一起很快就解决了这个问题，所以我只能分享它，没有提供任何经验。
