如何获取屏幕的状态以及横屏与竖屏自动切换

demo1:获取屏幕的状态 ，横屏与竖屏自动切换fragment

public class MainActivity extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //获取屏幕的宽度和高度  适配不同的fragment
        DisplayMetrics outMetrics=new DisplayMetrics();
        getWindowManager().getDefaultDisplay().getMetrics(outMetrics);
        int width=outMetrics.widthPixels;
        int height=outMetrics.heightPixels;
        RelativeLayout layout=(RelativeLayout)findViewById(R.id.layoutId);
        //要借助此对象管理fragment对象
        FragmentManager fm= getFragmentManager();
        FragmentTransaction ft=fm.beginTransaction();
        //使用不同的fragment
        if(height>width){
        ft.replace(R.id.layoutId, new Fragment01(),"tag");
        }else{
        ft.replace(R.id.layoutId, new Fragment02(),"tag");
        }
        //可选：将fragment添加到回退栈
        //ft.addToBackStack(null);
        ft.commit();
    }
    @Override
    protected void onResume() {
        super.onResume();
        //根据tag找到对应的fragment
        Fragment f=getFragmentManager().findFragmentByTag("tag");
        Log.i("TAG", "f="+f);
    }
}  

demo2:Tab+fragment 实现屏幕旋转保存数据

public class MainActivity extends Activity {
    ActionBar bar;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        bar=getActionBar();
        bar.setDisplayShowHomeEnabled(false);
        bar.setDisplayShowTitleEnabled(false);
        //设置为tab导航
        bar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
        //添加tab
        bar.addTab(bar.newTab().setText("tab01").setTabListener(
        new MyTabListener(this,Fragment01.class.getName(),"A")));
        bar.addTab(bar.newTab().setText("tab02").setTabListener(
        new MyTabListener(this,Fragment02.class.getName(),"B")));
    }
    @Override
   protected void onRestoreInstanceState(Bundle savedInstanceState) {
        super.onRestoreInstanceState(savedInstanceState);
        if(savedInstanceState!=null){
         int pos=savedInstanceState.getInt("posKey");
         bar.setSelectedNavigationItem(pos);    
        }
   }
   private class MyTabListener implements TabListener{
    private Context context;
    private String className;
    private Fragment frg;
    private String tag;
    public MyTabListener(Context context,String className,String tag){
        this.context=context;
        this.className=className;
        this.tag=tag;
        //检测在当前activity是否已经有存在的fragment
        Fragment frg=getFragmentManager().findFragmentByTag(tag);
        if(frg!=null&&!frg.isDetached()){
          FragmentTransaction beginTransaction = getFragmentManager().beginTransaction();
          beginTransaction.detach(frg);
          beginTransaction.commit();
        }
    }
    @Override
    public void onTabSelected(Tab tab, FragmentTransaction ft) {
        if(frg==null){
         frg=Fragment.instantiate(context, className);
         ft.add(R.id.layout,frg,tag);
        }else{
         ft.attach(frg);
        }
    }
    //没有选中的那个在旋转需要解除关联
    @Override
    public void onTabUnselected(Tab tab, FragmentTransaction ft) {
        if(frg!=null){
          ft.detach(frg);
        }
    }
    @Override
    public void onTabReselected(Tab tab, FragmentTransaction ft) {
    }
}
   @Override
  protected void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
    int pos=bar.getSelectedTab().getPosition();
    outState.putInt("posKey", pos);
   }
}