Activity 重启recreate() 重启Fragment

有这样一个场景，activity重启  activity.recareate()  但是会出现 如果启动很快，也就是在viewPager中添加fragment之前没有耗时的操作，

这时，系统会将没销毁的fragment重新附加到viewPager中，并没有新建一个fragment，fragment在初始化的时候先去manager中找寻没有销毁的标识的tagFragment,

FragmentPagerAdapter的bu分源码:尤其是instantiateItem方法

public abstract class FragmentPagerAdapter extends PagerAdapter {
    private static final String TAG = "FragmentPagerAdapter";
    private static final boolean DEBUG = false;

    private final FragmentManager mFragmentManager;
    private FragmentTransaction mCurTransaction = null;
    private Fragment mCurrentPrimaryItem = null;

    public FragmentPagerAdapter(FragmentManager fm) {
        mFragmentManager = fm;
    }

   .....

    @Override
    public Object instantiateItem(ViewGroup container, int position) {
        if (mCurTransaction == null) {
            mCurTransaction = mFragmentManager.beginTransaction();
        }

        final long itemId = getItemId(position);

        // Do we already have this fragment?
        String name = makeFragmentName(container.getId(), itemId);
        Fragment fragment = mFragmentManager.findFragmentByTag(name);
        if (fragment != null) {
            if (DEBUG) Log.v(TAG, "Attaching item #" + itemId + ": f=" + fragment);
            mCurTransaction.attach(fragment);
        } else {
            fragment = getItem(position);
            if (DEBUG) Log.v(TAG, "Adding item #" + itemId + ": f=" + fragment);
            mCurTransaction.add(container.getId(), fragment,
                    makeFragmentName(container.getId(), itemId));
        }
        if (fragment != mCurrentPrimaryItem) {
            fragment.setMenuVisibility(false);
            fragment.setUserVisibleHint(false);
        }

        return fragment;
    }
    .........

    public long getItemId(int position) {
        return position;
    }

    private static String makeFragmentName(int viewId, long id) {
        return "android:switcher:" + viewId + ":" + id;
    }
}

为了重启新建Fragment，我这里给出最简单的方法，在Activity的recareate()方法中移除fragment，

如:

   @Override
    public void recreate() {
        try {//避免重启太快 恢复
            FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
            for (Fragment fragment : fragmentAdapter.getFragmentsList()) {
                fragmentTransaction.remove(fragment);
            }
            fragmentTransaction.commitAllowingStateLoss();
        } catch (Exception e) {
        }
        super.recreate();
    }

这样在Activity在重启时,就会及时创建新的fragment