MVVM与DataBinding简单案例

一、MVVM

1.MVVM是什么

MVVM（Model–View–Viewmodel）是一种软件架构模式。

M----->Model层：请求的原始数据

V----->View层：视图展示，由ViewController来控制

VM---->ViewModel层：负责业务处理和数据转化

MVVM与MVC的不同

首先我们简化一下MVC的架构模式图：

讯享网

在这里，Controller需要做太多得事情，表示逻辑、业务逻辑，所以代码量非常的大。而MVVM：

在MVVM中，我们趋向于将view和view controller作为一个整体（这也解释了为什么不称它为MVVCVM),新的viewModel代替原来的viewController协调view与model之间的交互。

2.基本使用

创建好一个Android Project之后，在gradle文件中添加如下几行代码，表示开启databinding:

    dataBinding{

        enabled true

    }
    ...
}

3.以两个功能案例举例areacode(地区和区号)和topimage(图片加载)

二、areacode(地区和区号)

1.页面布局

2.主要model

3.VM:AreaCodeViewModel

3.activity

4.显示效果

三、topimage(图片加载)，添加RecyclerView展示数据列表

1.布局文件

2.主要model

3.VM之TopImageViewModel

public class TopImageViewModel { private List<ImgInfoModel> listImage = new ArrayList<>(); private List<ImgInfoModel> listImage_refresh = new ArrayList<>(); private DataBindingRecyclerViewAdapter adapter; public TopImageViewModel(final TopImageActivity activity) { OkHttpClient client = new OkHttpClient();//创建OkHttpClient对象 FormBody.Builder forBody1 = new FormBody.Builder();//创建表单请求体 forBody1.add("LANGUAGE", String.valueOf(0));//传递键值对参数 forBody1.add("CURR", "RMB");//传递键值对参数 forBody1.add("NO_DEVICE", String.valueOf(1));//传递键值对参数 FormBody.Builder forBody = new FormBody.Builder();//创建表单请求体 forBody.add("COMMONINFO", String.valueOf(forBody1));//传递键值对参数 forBody.add("TOKENINFO", "");//传递键值对参数 forBody.add("VIPCONTENT", "");//传递键值对参数 Request request = new Request.Builder()//创建Request 对象 .url("https://xxxxxxxxxxxxxxx")//接口 .post(forBody.build())//传递请求体 .build(); client.newCall(request).enqueue(new Callback() { @Override public void onFailure(@NotNull Call call, @NotNull IOException e) { Log.d("kwwl", "获取数据失败----"); } @Override public void onResponse(@NotNull Call call, @NotNull Response response) throws IOException { // Log.d("kwwl", "获取数据成功了----"); // Log.d("kwwl", "response.code()---==" + response.code()); // Log.d("kwwl", "response.body().string()---==" + response.body().string()); RImgInfoModel model = new Gson().fromJson(response.body().string(), RImgInfoModel.class); if (model.getRESULTCODE().getVIPCODE() == 0) { listImage.addAll(model.getVIPCONTENT()); listImage_refresh.addAll(listImage); //Only the original thread that created a view hierarchy can touch its views //翻译过来：只有创建这个view的线程才能操作这个view //在使用Volley的时候这个问题就不怎么会遇到了，那是因为无论是HttpURLConnection还是OkHttp //最终的回调接口，即onResponse运行在子线程 //所以一旦在回调接口对UI进行了操作，将会出现上述提示 //一般来讲，会使用handle解决这个问题 activity.runOnUiThread(new Runnable() { public void run() { adapter = new DataBindingRecyclerViewAdapter(activity, R.layout.item_image, com.dawn.mvvmanddatabinding.BR.imgItem, listImage); activity.binding.recyclerView.setLayoutManager(new LinearLayoutManager(activity, LinearLayoutManager.VERTICAL, false)); activity.binding.recyclerView.setAdapter(adapter); adapter.setOnItemCkickListener(new DataBindingRecyclerViewAdapter.ItemClickListener() { @Override public void itemClick(View view, int position) { Log.e("111",listImage.get(position).getST_IMGENGNAME()+"---"); Toast.makeText(activity, listImage.get(position).getST_IMGPATH()+"----"+position, Toast.LENGTH_LONG).show(); } }); } }); } else Log.d("kwwl", model.getRESULTCODE().getVIPINFO() + "================"); } }); } public void refresh() { listImage.clear(); if (listImage_refresh.size() != 0) listImage.addAll(listImage_refresh); adapter.notifyDataSetChanged(); } public void remove() { if (listImage.size() != 0) listImage.remove(0); adapter.notifyDataSetChanged(); } public void add() { ImgInfoModel p = new ImgInfoModel(); p.setST_IMGENGNAME("我爱吃水果 --新增的图片"); p.setST_IMGPATH("https://ss0.bdstatic.com/70cFvHSh_Q1YnxGkpoWK1HF6hhy/it/u=,&fm=26&gp=0.jpg"); listImage.add(0, p); adapter.notifyDataSetChanged(); } }

4.适配器布局

5.适配器代码

讯享网public class DataBindingRecyclerViewAdapter extends RecyclerView.Adapter<DataBindingRecyclerViewAdapter.ViewHolder> { Context mContext; int mLayoutId; int mVarId; private List mData; public static final int TYPE_HEADER = 1, TYPE_FOOTER = 2, TYPE_NORMAL = 0; boolean haveHeader = false; boolean haveFooter = false; View headerView, footerView; private ItemClickListener itemClickListener; public OnBindingViewHolderListener onBindingViewHolderListener; public DataBindingRecyclerViewAdapter(Context context, int layoutId, int varId, List data) { mContext = context; mLayoutId = layoutId; mVarId = varId; mData = data; } public void setOnItemCkickListener(ItemClickListener listener) { this.itemClickListener = listener; } public void setOnBindingViewHolderListener(OnBindingViewHolderListener listener) { onBindingViewHolderListener = listener; } @Override public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { switch (viewType) { case TYPE_HEADER: return new ViewHolder(headerView, viewType); case TYPE_FOOTER: return new ViewHolder(footerView, viewType); case TYPE_NORMAL: return new ViewHolder(LayoutInflater.from(mContext).inflate(mLayoutId, parent, false), viewType); default: return new ViewHolder(LayoutInflater.from(mContext).inflate(mLayoutId, parent, false), viewType); } } @Override public void onBindViewHolder(final ViewHolder holder, final int position) { switch (holder.viewType) { case TYPE_HEADER: break; case TYPE_FOOTER: break; case TYPE_NORMAL: default: ViewDataBinding binding = DataBindingUtil.bind(holder.itemView); Object data; if (haveHeader) { data = mData.get(position - 1); } else { data = mData.get(position); } if (itemClickListener != null) { holder.itemView.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { itemClickListener.itemClick(holder.itemView, position); } }); } binding.setVariable(mVarId,data); binding.executePendingBindings(); if (onBindingViewHolderListener != null) { onBindingViewHolderListener.onHolderBinding(holder, position); } break; } } / * 调用之后请调用NotifyDataSetChange 如果在setAdapter之后 * * @param view */ public void addFooterView(View view) { haveFooter = true; footerView = view; } / * 调用之后请调用NotifyDataSetChange 如果在setAdapter之后 * * @param view */ public void addHeaderView(View view) { haveHeader = true; headerView = view; } public void removeFooterView() { footerView = null; haveFooter = false; } public View getFooterView() { return footerView; } public void cleanData() { mData.clear(); notifyDataSetChanged(); } public List getAllData() { return mData; } public void addData(List data) { mData.addAll(data); notifyDataSetChanged(); } @Override public int getItemCount() { int extraCount = 0; if (haveHeader) { extraCount++; } else if (haveFooter) { extraCount++; } return mData.size() + extraCount; } @Override public int getItemViewType(int position) { if (position == 0 && haveHeader) { return TYPE_HEADER; } else if (position == mData.size() && haveFooter) { return TYPE_FOOTER; } else { return TYPE_NORMAL; } } public class ViewHolder extends RecyclerView.ViewHolder { int viewType; public ViewHolder(View itemView, int viewType) { super(itemView); this.viewType = viewType; } } public interface ItemClickListener { void itemClick(View view, int position); } public interface OnBindingViewHolderListener { void onHolderBinding(ViewHolder holder, int position); } }

6.加载适配器图片代码

7.activity代码

8.效果图