android - 用单Activity，多个Fragment做一个应用，应该如何实现？

Question

如题，用单Activity，多个Fragment做一个应用，应该如何实现？

Answer 1

強烈不建議這麼玩: 如果頁面很多, 而且又沒管理好Fragment, 那很有可能 OOM...

如果非要這樣玩, 請參考FragmentStatePagerAdapter的管理方式. 關鍵代碼如下:

public abstract class FragmentStatePagerAdapter extends PagerAdapter {
    @Override
    public Object instantiateItem(ViewGroup container, int position) {
        // If we already have this item instantiated, there is nothing
        // to do.  This can happen when we are restoring the entire pager
        // from its saved state, where the fragment manager has already
        // taken care of restoring the fragments we previously had instantiated.
        if (mFragments.size() > position) {
            Fragment f = mFragments.get(position);
            if (f != null) {
                return f;
            }
        }

        if (mCurTransaction == null) {
            mCurTransaction = mFragmentManager.beginTransaction();
        }

        Fragment fragment = getItem(position);
        if (DEBUG) Log.v(TAG, "Adding item #" + position + ": f=" + fragment);
        if (mSavedState.size() > position) {
            Fragment.SavedState fss = mSavedState.get(position);
            if (fss != null) {
                fragment.setInitialSavedState(fss);
            }
        }
        while (mFragments.size() <= position) {
            mFragments.add(null);
        }
        fragment.setMenuVisibility(false);
        fragment.setUserVisibleHint(false);
        mFragments.set(position, fragment);
        mCurTransaction.add(container.getId(), fragment);

        return fragment;
    }

    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {
        Fragment fragment = (Fragment) object;

        if (mCurTransaction == null) {
            mCurTransaction = mFragmentManager.beginTransaction();
        }
        if (DEBUG) Log.v(TAG, "Removing item #" + position + ": f=" + object
                + " v=" + ((Fragment)object).getView());
        while (mSavedState.size() <= position) {
            mSavedState.add(null);
        }
        mSavedState.set(position, fragment.isAdded()
                ? mFragmentManager.saveFragmentInstanceState(fragment) : null);
        mFragments.set(position, null);

        mCurTransaction.remove(fragment);
    }

}

除此之外, Activity有NavigateUp(向上導航) 和BackPressed(回退鍵) 的功能, 因此, 還要管理Activity有 NavigateUp(向上导航) 和 BackPressed(回退键) 的功能, 因此, 还要管理Fragment的回退栈(和Activity的回退栈是不一样的), 即调用 FragmentTransaction#addToBackStack(String)的回退棧(和Activity的回退棧是不一樣的), 即呼叫FragmentTransaction#addToBackStack(String).

Answer 2

建議同上面的回答一樣，盡量不要這樣搞。
希望你可以分析一下需要處理的幾個頁面，是否是同样性质的。比如說網易新聞，不同頻道所展現的內容是類似的，所以使用Fragment比較適合。但設定項中，各設定項中內容比較獨立，使用不同的Activity比較好。