//DEMO

public class MainActivity extends FragmentActivity implements TabListener {
	ViewPager viewPager;
	ActionBar bar;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);

		viewPager = (ViewPager) findViewById(R.id.viewpager);

		Fragment[] fragmentArray = new Fragment[] { new AFragmentTab(),
				new BFragmentTab(), new CFragmentTab() };
		HKFragmentPagerAdapter adapter = new HKFragmentPagerAdapter(
				getSupportFragmentManager(), fragmentArray);

		viewPager.setAdapter(adapter);
		viewPager.setOnPageChangeListener(new OnPageChangeListener() {

			@Override
			public void onPageSelected(int position) {
				bar.setSelectedNavigationItem(position);
			}

			@Override
			public void onPageScrolled(int arg0, float arg1, int arg2) {
			}

			@Override
			public void onPageScrollStateChanged(int arg0) {
			}
		});

		bar = getActionBar();
		bar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
		// fragmentArray.length()是多少,这里就是多少个TAB
		ActionBar.Tab tabA = bar.newTab().setText("A Tab");
		ActionBar.Tab tabB = bar.newTab().setText("B Tab");
		ActionBar.Tab tabC = bar.newTab().setText("C Tab");
		tabA.setTabListener(this);
		tabB.setTabListener(this);
		tabC.setTabListener(this);
		bar.addTab(tabA);
		bar.addTab(tabB);
		bar.addTab(tabC);
	}

	public void onTabSelected(Tab tab, FragmentTransaction ft) {
		viewPager.setCurrentItem(tab.getPosition());
	}

	public void onTabUnselected(Tab tab, FragmentTransaction ft) {
	}

	public void onTabReselected(Tab tab, FragmentTransaction ft) {
	}

}




标准的FragmentPagerAdapter适配器
public class HKFragmentPagerAdapter extends FragmentPagerAdapter {
	Fragment[] fragmentArray;

	public HKFragmentPagerAdapter(FragmentManager fm, Fragment[] fragmentArray) {
		super(fm);
		if (null == fragmentArray) {
			this.fragmentArray = new Fragment[] {};
		} else {
			this.fragmentArray = fragmentArray;
		}
	}

	@Override
	public Fragment getItem(int position) {
		return fragmentArray[position];
	}

	@Override
	public int getCount() {
		return fragmentArray.length;
	}
}



//Fragment的写法
public class AFragmentTab extends Fragment {
	@Override
	public View onCreateView(LayoutInflater inflater, ViewGroup container,
			Bundle savedInstanceState) {
		return inflater.inflate(R.layout.fragment_a, container, false);
	}
}