在文件存儲(chǔ)部分，利用RecyclerView和SQLite搭建了一個(gè)讀取本地?cái)?shù)據(jù)庫內(nèi)容將其顯示到列表的demo，這里需要注意的就是數(shù)據(jù)庫的基礎(chǔ)操作和RecyclerView的適配器部分，還需要熟練其流程才能掌握。今天的內(nèi)容是結(jié)合之前做的底部導(dǎo)航欄，在切換fragment的時(shí)候顯示列表，其實(shí)實(shí)現(xiàn)過程和在Activity里面是類似的。

一、流程

還是梳理一下具體的流程，我的流程如下：

1. 在fragment的布局文件中加入RecyclerView的控件；
2. 寫一個(gè)要顯示的item布局；
3. 寫一個(gè)POJO類，即一個(gè)Item類，設(shè)置要顯示的變量和構(gòu)造器，setter and getter；
4. 寫一個(gè)工廠類，用于制造item；
5. 主要的是適配器的書寫
6. 在fragment里面實(shí)例化，設(shè)置一些RecyclerView的屬性

貼上適配器的代碼

public class HomeAdapter extends RecyclerView.Adapter <HomeAdapter.MyHolder>{
    Context context;
    private List<HomeItem> list;

    public HomeAdapter(Context context, List<HomeItem> list) {
        this.context = context;
        this.list = list;
    }

    @NonNull
    @Override
    public MyHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from (parent.getContext ()).inflate (R.layout.home_list_item_layout,parent,false);
        MyHolder holder = new MyHolder (view);
        return holder;
    }

    @Override
    public void onBindViewHolder(@NonNull MyHolder holder, int position) {
        HomeItem item = list.get (position);
        Glide.with (context).load (item.getImgUrl ()).into (holder.ivImage);
        holder.tvTitle.setText (item.getImgTitle ());
        holder.tvAuthor.setText (item.getImgAuthor ());
        holder.tvInfo.setText (item.getImgInfo ());

    }

    @Override
    public int getItemCount() {
        return list.size ();
    }

    class MyHolder extends RecyclerView.ViewHolder {
        RelativeLayout itemLayout;
        ImageView ivImage;
        TextView tvTitle;
        TextView tvAuthor;
        TextView tvInfo;
        public MyHolder(View itemView) {
            super (itemView);
            itemLayout = itemView.findViewById (R.id.home_list_item_layout_rl);
            ivImage = itemView.findViewById (R.id.home_list_item_image_iv);
            tvTitle = itemView.findViewById (R.id.home_list_item_title_tv);
            tvAuthor = itemView.findViewById (R.id.home_list_item_author_tv);
            tvInfo = itemView.findViewById (R.id.home_list_item_info_tv);

        }
    }
}

二、 注意事項(xiàng)

在fragment實(shí)例化的時(shí)候注意fragment的生命周期，要在onCreateView()中進(jìn)行。

@Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View view = inflater.inflate(R.layout.fragment_home, container, false);
        mRecyclerView = view.findViewById (R.id.home_recycler_view_layout);
        homeAdapter = new HomeAdapter (getActivity (),list);
        mRecyclerView.setLayoutManager (new LinearLayoutManager (getActivity (),LinearLayoutManager.VERTICAL,false));
        mRecyclerView.setItemAnimator (new DefaultItemAnimator ());
        mRecyclerView.setAdapter (homeAdapter);
        mRecyclerView.addItemDecoration (new DividerItemDecoration (getActivity (),DividerItemDecoration.VERTICAL));
        return view;
    }

三、 Gson的使用

今天還測(cè)試了一下Gson的使用，解析json數(shù)據(jù)?？梢越Y(jié)合item的數(shù)據(jù)用Gson解析后進(jìn)行顯示