Fragment切换返回

1.开发中遇到需要在Fragment之间切换,保存状态

(1).初始化Fragment:

public void initFragment(){
        FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
        ft.replace(R.id.fl_container,onCreteFragment());
        ft.commitAllowingStateLoss();//允许丢失,一般可以不用这个采用commit()替代
}

(2).切换Fragment算法:

public void switchFragment(Fragment from, Fragment to) {
        FragmentTransaction mFragmentTransaction = getSupportFragmentManager().beginTransaction();
        if (!to.isAdded()) { // 先判断是否被add过
            mFragmentTransaction.hide(from).add(R.id.fl_container, to)
                    .commit(); // 隐藏当前的fragment，add下一个到Activity中
        } else {
            mFragmentTransaction.hide(from).show(to).commit(); // 隐藏当前的fragment，显示下一个
        }
}

(3).封装返回监听,采用弱引用和静态内部类,避免内存泄漏

public static class MyOnBackListener implements BaseFragment.OnBackListener {
        private final WeakReference<BaseFragment> mBaseFragment;//目的Fragment
        private final WeakReference<BaseFragmentActivity> mBaseActivity;
        /**
         * @param toFragment 跳转目的Fragment
         * @param baseActivit 当前BaseActivity
         */
        public MyOnBackListener(BaseFragment toFragment,BaseFragmentActivity baseActivit) {
            mBaseFragment =new WeakReference<>(toFragment);
            mBaseActivity =new WeakReference<>(baseActivit);
        }

        @Override
        public void back(BaseFragment baseFragment) {
            BaseFragmentActivity baseActivity = mBaseActivity.get();
            BaseFragment baseFragment2 = mBaseFragment.get();
            if (baseActivity !=null&& baseFragment2 !=null&&baseFragment!=null){
                baseActivity.switchFragment(baseFragment,baseFragment2);
            }
        }
    }

(4).Activity中简单使用:

private void initLocalFragment() {
        mRfbf = new RecyclerFabBehaviorFragment();
        mRfbf.setOnBackListener(new MyOnBackListener(mStartRecycFragment,this));
 }

@Override
public void click(View view, int position) {
        switch (position){
            case 0:
                switchFragment(mStartRecycFragment, mRfbf);
                break;
        }
 }

(5).子类Fragment中记得调用back:eg 

TabyoutViewPagerFragment extends BaseFragment

private void initToolbar() {
        mToolbar.setNavigationOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (mOnBackListener!=null){
                    mOnBackListener.back(TabyoutViewPagerFragment.this);
                }
            }
        });
}

(6).可以采用鸿阳的FABridge来简化Fragment中定义接口在Activity中回调

annotationProcessor 'com.zhy.fabridge:fabridge-compiler:1.0.0'
implementation 'com.zhy.fabridge:fabridge-api:1.0.0'

Fragment中定义

Fabridge.call(getActivity(), EVENT_CLICK, "来了");

Activity中使用

@FCallbackId(id = FabrigeSampleFragment.EVENT_CLICK)
public void menuItemClick(String title)
{
    Toast.makeText(this, ""+title+","+Thread.currentThread().getName(), Toast.LENGTH_SHORT).show();
}