<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:tools="http://schemas.android.com/tools"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:orientation="horizontal"
  tools:context=".MainActivity" >

  <fragment
    android:id="@+id/fragment1"
    android:name="com.wuyudong.fragment.Fragment1"
    android:layout_width="0dip"
    android:layout_height="fill_parent"
    android:layout_weight="1" >
  </fragment>

  <fragment
    android:id="@+id/fragment2"
    android:name="com.wuyudong.fragment.Fragment2"
    android:layout_width="0dip"
    android:layout_height="fill_parent"
    android:layout_weight="1" >
  </fragment>

</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:background="#0000ff"
  android:orientation="vertical" >
</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:background="#ff00"
  android:orientation="vertical" >
</LinearLayout>

public class Fragment1 extends Fragment {
  /**
   * 当fragment被创建的时候，调用的方法，返回当前fragment显示的内容 
   */
  @Override
  public View onCreateView(LayoutInflater inflater, ViewGroup container,
      Bundle savedInstanceState) {
    return inflater.inflate(R.layout.fragment1, null);
  }

}

public class Fragment2 extends Fragment {
  /**
   * 当fragment被创建的时候，调用的方法，返回当前fragment显示的内容 
   */
  @Override
  public View onCreateView(LayoutInflater inflater, ViewGroup container,
      Bundle savedInstanceState) {
    return inflater.inflate(R.layout.fragment2, null);
  }

}

public class MainActivity extends Activity {

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

    // 1、判断当前手机的朝向
    int width = getWindowManager().getDefaultDisplay().getWidth();
    int height = getWindowManager().getDefaultDisplay().getHeight();
    Fragment1 fragment1 = new Fragment1();
    Fragment2 fragment2 = new Fragment2();

    FragmentManager fm = getFragmentManager();
    FragmentTransaction ft = fm.beginTransaction();

    if (width > height) {
      // 水平方向
      ft.replace(android.R.id.content, fragment1);
    } else {
      ft.replace(android.R.id.content, fragment2);
    }

    ft.commit();

  }

}