Android笔记之Actionbar制作选项卡（可滑动）

1、主要代码：

API:http://developer.android.com/reference/android/app/ActionBar.html

(1)不需要activity_main.xml文件

(2)MainActivity和fragment_1类都继承android.app.Fragment，而不是V4的

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        final ActionBar actionBar;
        actionBar = getActionBar();
        //使Tab显示出来
        actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
        //不显示标题和图标
        actionBar.setDisplayShowTitleEnabled(false);
        actionBar.setDisplayShowHomeEnabled(false);
        
        //添加tab
        actionBar.addTab(actionBar
                .newTab()
                .setText("选项卡一")
                .setIcon(null)
                .setTabListener(
                        new TabListener<fragment_1>(this, null, fragment_1.class)));
        actionBar.addTab(actionBar
                .newTab()
                .setText("选项卡二")
                .setIcon(null)
                .setTabListener(
                        new TabListener<fragment_1>(this, null, fragment_1.class)));
        actionBar.addTab(actionBar
                .newTab()
                .setText("选项卡三")
                .setIcon(null)
                .setTabListener(
                        new TabListener<fragment_1>(this, null, fragment_1.class)));
    }

    public static class TabListener<T extends Fragment> implements ActionBar.TabListener {
        private final Activity mActivity;
        private final String mTag;
        private final Class<T> mClass;
        private final Bundle mArgs;
        private Fragment mFragment;

        public TabListener(Activity activity, String tag, Class<T> clz) {
            this(activity, tag, clz, null);
        }

        public TabListener(Activity activity, String tag, Class<T> clz, Bundle args) {
            mActivity = activity;
            mTag = tag;
            mClass = clz;
            mArgs = args;

            // Check to see if we already have a fragment for this tab, probably
            // from a previously saved state.  If so, deactivate it, because our
            // initial state is that a tab isn't shown.
            mFragment = mActivity.getFragmentManager().findFragmentByTag(mTag);
            if (mFragment != null && !mFragment.isDetached()) {
                FragmentTransaction ft = mActivity.getFragmentManager().beginTransaction();
                ft.detach(mFragment);
                ft.commit();
            }
        }

        public void onTabSelected(Tab tab, FragmentTransaction ft) {
            if (mFragment == null) {
                mFragment = Fragment.instantiate(mActivity, mClass.getName(), mArgs);
                ft.add(android.R.id.content, mFragment, mTag);
            } else {
                ft.attach(mFragment);
            }
        }

        public void onTabUnselected(Tab tab, FragmentTransaction ft) {
            if (mFragment != null) {
                ft.detach(mFragment);
            }
        }

        public void onTabReselected(Tab tab, FragmentTransaction ft) {
            Toast.makeText(mActivity, "Reselected!", Toast.LENGTH_SHORT).show();
        }
    }

2、结合ViewPager实现可滑动选项卡

API:     http://developer.android.com/reference/android/support/v4/view/ViewPager.html

 (1)主要代码：

import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.app.FragmentTransaction;
import android.support.v4.view.ViewPager;

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.tab_pager);
        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"), fragment_1.class,
                null);
        mTabsAdapter.addTab(bar.newTab().setText("List"), fragment_1.class,
                null);
        mTabsAdapter.addTab(bar.newTab().setText("Cursor"), fragment_1.class,
                null);

        if (savedInstanceState != null) {
            bar.setSelectedNavigationItem(savedInstanceState.getInt("tab", 0));
        }
    }

    @Override
    protected void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        outState.putInt("tab", getActionBar().getSelectedNavigationIndex());
    }

    /**
     * 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.
     */
    public static 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;

            TabInfo(Class<?> _class, Bundle _args) {
                clss = _class;
                args = _args;
            }
        }

        public TabsAdapter(Activity activity, ViewPager pager) {
            super(((FragmentActivity) 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 int getCount() {
            return mTabs.size();
        }

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

        @Override
        public void onPageScrolled(int position, float positionOffset,
                int positionOffsetPixels) {
        }

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

        @Override
        public void onPageScrollStateChanged(int state) {
        }

        public void onTabSelected(Tab tab, FragmentTransaction ft) {
            Object tag = tab.getTag();
            for (int i = 0; i < mTabs.size(); i++) {
                if (mTabs.get(i) == tag) {
                    mViewPager.setCurrentItem(i);
                }
            }
        }

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

        }

        @Override
        public void onTabSelected(Tab tab, android.app.FragmentTransaction ft) {
            // TODO Auto-generated method stub

        }

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

        }

    }
}

(2)xml文件加个Viewpager就可以了

(3)注意结合Viewpage的选项卡都要使用V4下的包，与第一个不同

(4)主Activity必须继承FragmentActivity

Done!