try {
  Field field = popupMenu.getClass().getDeclaredField("mPopup");
  field.setAccessible(true);
  MenuPopupHelper mHelper = (MenuPopupHelper) field.get(popupMenu);
  mHelper.setForceShowIcon(true);
} catch (IllegalAccessException | NoSuchFieldException e) {
  e.printStackTrace();
}

<menu xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:app="http://schemas.android.com/apk/res-auto">
  <group android:checkableBehavior="single">
    <item
      android:id="@+id/menu_setting_wifi"
      android:title="使用WIFI"
      android:orderInCategory="80"
      android:icon="@drawable/menu_setting_wifi"
      app:showAsAction="ifRoom" />
    <item
      android:id="@+id/menu_setting_gps"
      android:title="使用GPS"
      android:orderInCategory="90"
      android:icon="@drawable/menu_setting_gps"
      app:showAsAction="ifRoom" />
  </group>
  <group>
    <item
      android:id="@+id/menu_setting_userIcon"
      android:title="设置头像"
      android:icon="@drawable/menu_setting_usericon"
      android:orderInCategory="91"
      app:showAsAction="never" />
  </group>
</menu>

<!--自定义PopupMenu上的RadioButton的样式-->
  <style name="PopupMenuStyle" parent="AppTheme">
    <item name="android:radioButtonStyle">@style/MenuRadioButtonStyle</item>
  </style>
  <style name="MenuRadioButtonStyle" parent="@android:style/Widget.CompoundButton.RadioButton">
    <item name="android:button">@drawable/selector_menu_rb</item>
  </style>

<activity
  android:name=".PopupMenuActivity"
  android:theme="@style/PopupMenuStyle" />

Context wrapper = new ContextThemeWrapper(activity, R.style.PopupMenuStyle);
PopupMenu popupMenu = new PopupMenu(activity, ancher);

/**
 * 自定义PopupMenu
 * Created by hanj on 15-3-17.
 */
public class PopupMenuActivity extends Activity {
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    LinearLayout lin = new LinearLayout(this);
    Button btn = new Button(this);
    LinearLayout.LayoutParams p = new LinearLayout.LayoutParams(
        LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT);
    btn.setLayoutParams(p);
    lin.addView(btn);
    btn.setText("显示PopupMenu");
    btn.setOnClickListener(new View.OnClickListener() {
      @Override
      public void onClick(View v) {
        showPopupMenu(PopupMenuActivity.this, v);
      }
    });
    setContentView(lin);
  }
  //当前选择的menuItem的id
  private int checkedItemId = R.id.menu_setting_wifi;
  private void showPopupMenu(final Context context, View ancher) {
    PopupMenu popupMenu = new PopupMenu(context, ancher);
    //引入菜单资源
    popupMenu.inflate(R.menu.menu_popup);
    //设置选中
    popupMenu.getMenu().findItem(checkedItemId).setChecked(true);
    //菜单项的监听
    popupMenu.setOnMenuItemClickListener(new PopupMenu.OnMenuItemClickListener() {
      @Override
      public boolean onMenuItemClick(MenuItem menuItem) {
        switch (menuItem.getItemId()) {
          case R.id.menu_setting_wifi:
            checkedItemId = R.id.menu_setting_wifi;
            Toast.makeText(context, "WIFI", Toast.LENGTH_SHORT).show();
            break;
          case R.id.menu_setting_gps:
            checkedItemId = R.id.menu_setting_gps;
            Toast.makeText(context, "GPS", Toast.LENGTH_SHORT).show();
            break;
          case R.id.menu_setting_userIcon:
            Toast.makeText(context, "USER_ICON", Toast.LENGTH_SHORT).show();
            break;
        }
        return true;
      }
    });
    //使用反射，强制显示菜单图标
    try {
      Field field = popupMenu.getClass().getDeclaredField("mPopup");
      field.setAccessible(true);
      MenuPopupHelper mHelper = (MenuPopupHelper) field.get(popupMenu);
      mHelper.setForceShowIcon(true);
    } catch (IllegalAccessException | NoSuchFieldException e) {
      e.printStackTrace();
    }
    //显示PopupMenu
    popupMenu.show();
  }
}