ViewPager实现TabHost 效果

import android.os.Bundle;
import android.app.ActionBar;
import android.support.v4.app.FragmentActivity;
import android.support.v4.view.ViewPager;
import android.view.Menu;

public class MainActivity extends FragmentActivity {
ViewPager mViewPager;
TabsAdapter mTabsAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mViewPager = new ViewPager(this);
mViewPager.setId(R.id.viewpager);
setContentView(mViewPager);

final ActionBar bar = getActionBar();
bar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
bar.setDisplayOptions(0, ActionBar.DISPLAY_SHOW_TITLE);

mTabsAdapter = new TabsAdapter(this, mViewPager);
mTabsAdapter.addTab(bar.newTab().setText("Simple"),
CountingFragment.class, null);
mTabsAdapter.addTab(bar.newTab().setText("第二个"),
SecondFragment.class, null);
mTabsAdapter.addTab(bar.newTab().setText("Cursor"),
CursorFragment.class, null);

if(savedInstanceState != null){
bar.setSelectedNavigationItem(savedInstanceState.getInt("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);
outState.putInt("tab", getActionBar().getSelectedNavigationIndex());
}

}

import java.util.ArrayList;
import android.app.ActionBar;
import android.app.ActionBar.Tab;
import android.app.FragmentTransaction;
import android.content.Context;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;

public class TabsAdapter extends FragmentPagerAdapter implements
ActionBar.TabListener, ViewPager.OnPageChangeListener{
private final Context mContext;
private final ActionBar mActionBar;
private final ViewPager mViewPager;
private final ArrayList<TabInfo> mTabs = new ArrayList<TabInfo>();

static final class TabInfo{
private final Class<?> clss;
private final Bundle args;

public TabInfo(Class<?> _class, Bundle _args) {
clss = _class;
args = _args;
}
}
public TabsAdapter(FragmentActivity activity, ViewPager pager) {
super(activity.getSupportFragmentManager());
mContext = activity;
mActionBar = activity.getActionBar();
mViewPager = pager;
mViewPager.setAdapter(this);
mViewPager.setOnPageChangeListener(this);
}

public void addTab(ActionBar.Tab tab, Class<?> clss, Bundle args){
TabInfo info = new TabInfo(clss, args);
tab.setTag(info);
tab.setTabListener(this);
mTabs.add(info);
mActionBar.addTab(tab);
notifyDataSetChanged();
}

@Override
public Fragment getItem(int position) {
TabInfo info = mTabs.get(position);
return Fragment.instantiate(mContext, info.clss.getName(), info.args);
}

@Override
public int getCount() {
// TODO Auto-generated method stub
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(Tab tab, FragmentTransaction ft) {
// TODO Auto-generated method stub
Object tag = tab.getTag();
for( int i=0; i<mTabs.size(); i++){
if(mTabs.get(i) == tag){
mViewPager.setCurrentItem(i);
}
}
}

@Override
public void onTabUnselected(Tab tab, FragmentTransaction ft) {
// TODO Auto-generated method stub

}

@Override
public void onTabReselected(Tab tab, FragmentTransaction ft) {
// TODO Auto-generated method stub

}

}

public class CountingFragment extends Fragment
{
private String mTitle = "First Fragment";

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState)
{

TextView tv = new TextView(getActivity());
tv.setTextSize(20);
tv.setBackgroundColor(Color.parseColor("#ffffffff"));
tv.setText(mTitle);
tv.setGravity(Gravity.CENTER);
return tv;

}
}

public class SecondFragment extends Fragment
{
private String mTitle = "Second Fragment";

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState)
{

TextView tv = new TextView(getActivity());
tv.setTextSize(20);
tv.setBackgroundColor(Color.parseColor("#ffffffff"));
tv.setText(mTitle);
tv.setGravity(Gravity.CENTER);
return tv;

}
}

public class CursorFragment extends Fragment
{
private String mTitle = "Third Fragment";

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState)
{

TextView tv = new TextView(getActivity());
tv.setTextSize(20);
tv.setBackgroundColor(Color.parseColor("#ffffffff"));
tv.setText(mTitle);
tv.setGravity(Gravity.CENTER);
return tv;

}
}

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity" >
<android.support.v4.view.ViewPager
android:id="@+id/viewpager"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:overScrollMode="never" >

</android.support.v4.view.ViewPager>

</RelativeLayout>