淘宝相信大家都在用过，不过不知道各位有没有仔细观察过淘宝的tab界面，尤其是返回的时候的逻辑。最近闲来无事，猛然发现淘宝的tab界面还真的挺好玩，废话不多说，接下来就开始我们的正题：

        首先，我们先来分析一下他的返回逻辑，仔细观察你会发现，他并不是你一点返回就会让你退，而是只有你在主界面的时候才会让你退出。当不在主界面时则会依次返回到你以前的界面，在主界面退出。如果重复点击同一个tab，则会把跳转到前一个相同tab，并把之后所有tab移除。

       好了，逻辑先分析到这里，大家可以打开手机淘宝慢慢体会。

public class Fragment1 extends Fragment{@Nullable@Overridepublic View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {TextView textView=new TextView(getActivity());textView.setText("Fragment1");return textView;}
}

   其他四个分别为： Fragment2 ，Fragment3 ，Fragment4 ，Fragment5，内容与上面代码一致，为了节省空间和时间，这里就不一    一列出

      接下里我们为fragment建立一个工厂类：

           

public class FragmentFactory {private  static SparseArray<Fragment> fragmentList=new SparseArray<>();   //fragment集合，保证每个fragment只被 实例一次public static Fragment getLocalFragment(int id) {Fragment fragment =fragmentList.get(id);if(fragment!=null)return  fragment;switch (id) {case R.id.id_main_radio:fragment = new Fragment1();break;case R.id.id_change_radio:fragment = new Fragment2();break;case R.id.id_record_radio:fragment = new Fragment3();break;case R.id.id_setting_radio:fragment = new Fragment4();break;case R.id.id_shenqing_radio:fragment = new Fragment5();break;}fragmentList.put(id,fragment);          //保存此fragment，方便下次调用return fragment;}
}

      接下来看main.xml的布局文件

<?xml version="1.0" encoding="utf-8"?><LinearLayoutandroid:layout_width="match_parent"android:layout_height="match_parent"android:orientation="vertical"xmlns:android="http://schemas.android.com/apk/res/android"><FrameLayoutandroid:id="@+id/frame"android:layout_width="fill_parent"android:layout_height="0dp"android:layout_weight="1" /><RelativeLayoutandroid:layout_width="match_parent"android:layout_height="wrap_content" ><RadioGroupandroid:id="@+id/tabgroup"android:layout_width="fill_parent"android:layout_height="52dp"android:layout_gravity="bottom"android:orientation="horizontal" ><RadioButtonandroid:id="@+id/id_main_radio"style="@style/weibo_tab"android:layout_width="fill_parent"android:layout_height="fill_parent"android:layout_weight="1"android:checked="true"android:drawableTop="@drawable/home"android:text="首页" /><RadioButtonandroid:id="@+id/id_change_radio"style="@style/weibo_tab"android:layout_width="fill_parent"android:layout_height="fill_parent"android:layout_weight="1"android:drawableTop="@drawable/myservice"android:text="我的服务" /><RadioButtonandroid:id="@+id/id_shenqing_radio"style="@style/weibo_tab"android:layout_width="fill_parent"android:layout_height="fill_parent"android:layout_weight="1"android:drawableTop="@drawable/myapply"android:text="申请" /><RadioButtonandroid:id="@+id/id_record_radio"style="@style/weibo_tab"android:layout_width="fill_parent"android:layout_height="fill_parent"android:layout_weight="1"android:drawableTop="@drawable/cart"android:text="购物车" /><RadioButtonandroid:id="@+id/id_setting_radio"style="@style/weibo_tab"android:layout_width="fill_parent"android:layout_height="fill_parent"android:layout_weight="1"android:drawableTop="@drawable/mine"android:text="我" /></RadioGroup></RelativeLayout>
</LinearLayout>

 style如下：

   <style name="weibo_tab"><item name="android:layout_height">wrap_content</item><item name="android:layout_width">match_parent</item><item name="android:layout_weight">1</item><item name="android:gravity">center</item><item name="android:paddingTop">8dip</item><item name="android:background">@drawable/background</item><item name="android:paddingBottom">4dip</item><item name="android:button">@null</item><item name="android:textSize">12sp</item><item name="android:textColor">@drawable/radiotext</item></style>

   最后就是我们的重中之重了，也就是我们的MainActivity:

   好了，至此，我们的仿淘宝tab返回就算是基本完成了，快来看看我们的效果吧：

项目下载地址：点击下载demo

public class MainActivity extends FragmentActivity implementsOnCheckedChangeListener {private static RadioGroup tab_group;private FragmentManager fragmentManager;public Context context;private int[] radioIds;              //存放所有Radiobutton的idprivate static Boolean isExit = false;private boolean isBack;    //记录是都是返回，如果是返回则不调用onCheckedChanged@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);requestWindowFeature(Window.FEATURE_NO_TITLE);setContentView(R.layout.main);context = MainActivity.this;initViews();fragmentManager = getSupportFragmentManager();FragmentTransaction transaction = fragmentManager.beginTransaction();Fragment mainFragment=FragmentFactory.getLocalFragment(R.id.id_main_radio);transaction.add(R.id.frame, mainFragment, R.id.id_main_radio + "");transaction.addToBackStack(R.id.id_main_radio + "");    //放入栈底，保证每次都从首页退出transaction.commit();ActivityManager.getInstance().addActivity(this);}private void initViews() {tab_group = (RadioGroup) findViewById(R.id.tabgroup);tab_group.setOnCheckedChangeListener(this);radioIds = new int[] { R.id.id_main_radio, R.id.id_change_radio,R.id.id_shenqing_radio,R.id.id_record_radio, R.id.id_setting_radio };}@Overridepublic void onCheckedChanged(RadioGroup group, int checkedId) {if(isBack){isBack=false;return;    }else {tab_group.check(tab_group.getCheckedRadioButtonId());FragmentTransaction transaction = fragmentManager.beginTransaction();Fragment fragment1=fragmentManager.findFragmentByTag(checkedId + "");if(fragment1==null){//如果为空，则表明此fragment从来没有被点击过fragment1 = FragmentFactory.getLocalFragment(checkedId);transaction.addToBackStack(checkedId+"");}else {//该fragment已经入栈boolean isCurrent=false;       //是否是当前栈for (int i=0,size=fragmentManager.getBackStackEntryCount();i<size;i++){String name=fragmentManager.getBackStackEntryAt(i).getName();  //获取当前栈名称if(isCurrent)fragmentManager.popBackStack();if(name.equals(checkedId+"")){isCurrent=true;}}}transaction.replace(R.id.frame, fragment1,checkedId+"");transaction.commit();}}@Overridepublic boolean onKeyDown(int keyCode, KeyEvent event) {if (keyCode == KeyEvent.KEYCODE_BACK) {FragmentManager fragmentManager=getSupportFragmentManager();int count=fragmentManager.getBackStackEntryCount();if(count>1){fragmentManager.popBackStack();isBack=true;BackStackEntry backstatck=getSupportFragmentManager().getBackStackEntryAt(count-1);RadioButton radioButton=(RadioButton) tab_group.findViewById(radioIds[(backstatck.getId()-1)%5]);radioButton.setChecked(true);}else {exitBy2Click();}}return false;}private void exitBy2Click() {Timer tExit = null;if (isExit == false) {isExit = true;Toast.makeText(this, "再按一次退出", Toast.LENGTH_SHORT).show();tExit = new Timer();tExit.schedule(new TimerTask() {@Overridepublic void run() {isExit = false;}}, 2000);} else {ActivityManager.getInstance().exit();}}
}