浅谈Android选项卡（三）

上一节介绍了TabActivity的简单用法，但是现在的Api中已经不建议使用了，建议使用Fragment来替代以上的功能，下面介绍下使用Fragment和ViewPager的结合使用。

http://blog.csdn.net/xia215266092/article/details/9613985

TabActivity的文档。

This class was deprecated in API level 13.
New applications should use Fragments instead of this class; to continue to run on older devices, you can use the v4 support library which provides a version of the Fragment API that is compatible down to DONUT.

下面的示例是使用android-support-v4.jar，写的demo，这个demo也是api的demo。

<android.support.v4.app.FragmentTabHost
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@android:id/tabhost"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <LinearLayout
        android:orientation="vertical"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <TabWidget
            android:id="@android:id/tabs"
            android:orientation="horizontal"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_weight="0"/>

        <FrameLayout
            android:id="@android:id/tabcontent"
            android:layout_width="0dp"
            android:layout_height="0dp"
            android:layout_weight="0"/>

        <FrameLayout
            android:id="@+id/realtabcontent"
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:layout_weight="1"/>

    </LinearLayout>
</android.support.v4.app.FragmentTabHost>

import com.example.android.supportv4.R;

import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentTabHost;

/**
 * This demonstrates how you can implement switching between the tabs of a
 * TabHost through fragments, using FragmentTabHost.
 */
public class FragmentTabs extends FragmentActivity {
    private FragmentTabHost mTabHost;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.fragment_tabs);
        mTabHost = (FragmentTabHost)findViewById(android.R.id.tabhost);
        mTabHost.setup(this, getSupportFragmentManager(), R.id.realtabcontent);

        mTabHost.addTab(mTabHost.newTabSpec("simple").setIndicator("Simple"),
                FragmentStackSupport.CountingFragment.class, null);
        mTabHost.addTab(mTabHost.newTabSpec("contacts").setIndicator("Contacts"),
                LoaderCursorSupport.CursorLoaderListFragment.class, null);
        mTabHost.addTab(mTabHost.newTabSpec("custom").setIndicator("Custom"),
                LoaderCustomSupport.AppListFragment.class, null);
        mTabHost.addTab(mTabHost.newTabSpec("throttle").setIndicator("Throttle"),
                LoaderThrottleSupport.ThrottledLoaderListFragment.class, null);
    }
}

但是今天讲的不是这个，我讲Fragment是Android4.0以后的Fragment，android.app.Fragment，v4扩展包里面也有Fragment，但是是不一样的。

下面是用的是4.0以后的fragment，编译的版本和手机必须是4.0以后的，还是我这边引用的是android-support-v13.jar，这个jar，不是v4的。

package org.liushui.tabdemo.frag;

import java.util.ArrayList;
import java.util.List;

import org.liushui.tabdemo.R;

import android.app.ActionBar;
import android.app.ActionBar.Tab;
import android.app.Activity;
import android.app.Fragment;
import android.app.FragmentTransaction;
import android.content.Context;
import android.os.Bundle;
import android.support.v13.app.FragmentStatePagerAdapter;
import android.support.v4.view.ViewPager;

public class MainFragmentActivity extends Activity {
	private ViewPager mViewPager;
	private TabsAdapter mTabsAdapter;

	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.frag_main);
		mViewPager = (ViewPager) findViewById(R.id.pager);

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

		mTabsAdapter = new TabsAdapter(this, mViewPager);
		mTabsAdapter.addTab(bar.newTab().setText("电话"), AFragment.class, null);
		mTabsAdapter.addTab(bar.newTab().setText("短信"), BFragment.class, null);
		mTabsAdapter.addTab(bar.newTab().setText("拨号"), CFragment.class, null);
	}

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

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

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

		public TabsAdapter(Activity activity, ViewPager pager) {
			super(activity.getFragmentManager());
			mContext = activity;
			mActionBar = activity.getActionBar();
			mViewPager = pager;
			mViewPager.setAdapter(this);
			mViewPager.setOnPageChangeListener(this);
			mViewPager.setOffscreenPageLimit(3);
		}

		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);
		}

		public int getCount() {
			return mTabs.size();
		}

		public int getItemPosition(Object object) {
			return POSITION_NONE;
		}

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

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

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

		public void onPageScrollStateChanged(int state) {
		}

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

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

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

布局文件是很简单的，就是一个ViewPager就可以了，关于ViewPager，有点类似Android手机上面的Launcher，可以左右滑动。

<?xml version="1.0" encoding="utf-8"?>

<android.support.v4.view.ViewPager
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/pager"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
</android.support.v4.view.ViewPager>

上面代码中的子页面，AFragment，BFragment，CFragment，都是继承Fragment的，注意使用的android.app.Fragment.

package org.liushui.tabdemo.frag;

import org.liushui.tabdemo.R;

import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

/**
 * Title: AFragment.java<br>
 * author:xiaqiulei@gmail.com <br>
 * Date: 2013年7月29日<br>
 * Version:v1.0
 */
public class AFragment extends Fragment {

	public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
		View view = inflater.inflate(R.layout.a, container, false);
		return view;
	}
}

onCreateView这个方法，就是返回一个界面对象，在ViewPager中显示。