轻松实现Android仿淘宝地区选择功能

最近用淘宝客户端的时候，编辑地址的时候有个地区选择的功能。看上面的效果觉得挺酷，滚动的时候，是最后一个从下面飞上来挨着前一个。就自己鼓捣一个出来玩玩。

说了效果可能不太直观，下面上两张图看看效果

淘宝地区选择效果

再来一张自己的效果

gif的效果可能不太好，大家自己用Android手机打开淘宝看看

实现分析

展示很简单，ListView就可以了。对于动画效果，只需要在getView的时候获取到要展示的View，通过属性动画修改translationY就ok啦。由于地区选择是一个界面，所以这里还用到了Fragment的 addToBackStack知识

1、用来展示的Fragment

用一个Fragment来接受parentCode参数来获取父地区的所有子地区，然后进行显示。这里用Fragment来做是因为用Activity的话，这样的连续点击都是同一类的界面不太适合。

public class AreaFragment extends Fragment implements AdapterView.OnItemClickListener {
 private static final String ARG_PARAM1 = "parentCode";
 @Bind(R.id.refresh_list_view)
 ListView mRefreshListView;
 @Bind(R.id.loadingBar)
 ProgressBar mLoadingBar;
 private String mParam1;//parentCode参数
 OkHttpClient mOkHttpClient = new OkHttpClient();
 private OnFragmentInteractionListener mListener;
 private AreaAdapter adapter;//地区adapter
 public AreaFragment() {
 }
 
 public static AreaFragment newInstance(String param1) {
  AreaFragment fragment = new AreaFragment();
  Bundle args = new Bundle();
  args.putString(ARG_PARAM1, param1);
  fragment.setArguments(args);
  return fragment;
 }
 @Override
 public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  if (getArguments() != null) {
   //获取父地区的code，用来查询子地区
   mParam1 = getArguments().getString(ARG_PARAM1);
  }
 }
 @Override
 public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
  // Inflate the layout for this fragment
  View view = inflater.inflate(R.layout.fragment_area, container, false);
  ButterKnife.bind(this, view);
  mRefreshListView.setOnItemClickListener(this);
  FORMEncodingBuilder builder = new FormEncodingBuilder();
  builder.add(ARG_PARAM1,mParam1);
  //通过parentCode来请求地区，如果parentCode不存在就是第一级
  final Request request = new Request.Builder()
    .url("http://123.184.16.19:8008/area/list")
    .post(builder.build())
    .build();
  mOkHttpClient.newCall(request).enqueue(new Callback(){
   @Override
   public void onFailure(Request request, IOException e) {
   }
   @Override
   public void onResponse(Response response) throws IOException {
    final String res = response.body().string();
    if (res!=null){
     Gson gson = new Gson();
     JSONResult jsonResult = gson.fromJson(res, JsonResult.class);
     if (jsonResult.isSuccess()){
      List list = (List) jsonResult.getResult();
      List newList = new ArrayList();
      Iterator iterator = list.iterator();
      while (iterator.hasNext()){
       Map map = (Map) iterator.next();
       AreaInfo areaInfo = gson.fromJson(gson.toJson(map),AreaInfo.class);
       newList.add(areaInfo);
      }
      adapter = new AreaAdapter(getContext(),newList);
      getActivity().runOnUiThread(new Runnable() {
       @Override
       public void run() {
      //拿到数据进行展示   
      mRefreshListView.setAdapter(adapter);
       }
      });
     }
    }
   }
  });
  return view;
 }
 @Override
 public void onAttach(Context context) {
  super.onAttach(context);
  if (context instanceof OnFragmentInteractionListener) {
   mListener = (OnFragmentInteractionListener) context;
  } else {
   throw new RuntimeException(context.toString()
     + " must implement OnFragmentInteractionListener");
  }
 }
 @Override
 public void onDetach() {
  super.onDetach();
  mListener = null;
 }
 @Override
 public void onDestroyView() {
  super.onDestroyView();
  ButterKnife.unbind(this);
 }
 @Override
 public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
  //单击的时候需要处理地区点击事件，统一交给Activity处理
  AreaInfo areaInfo = (AreaInfo) parent.getAdapter().getItem(position);
  if (areaInfo==null) return;
  if (mListener!=null){
   mListener.onFragmentInteraction(areaInfo);
  }
 }
 //用来和Activity交互的回调接口
 public interface OnFragmentInteractionListener {
  void onFragmentInteraction(AreaInfo areaInfo);
 }

我们用了一个Fragment来接受parentCode，用于请求下一级的地区，获取成功之后进行了展示。并且提供了一个OnFragmentInteractionListener用来在onItemClick时与Activity交互。

接下来看adapter,最开始我们提到了要实现淘宝的效果我们只需要拿到即将显示的View，设置动画就可以了。

2、处理显示效果的adapter

class AreaAdapter extends BaseAdapter {
  private List list;
  private int lastPosition;
  public AreaAdapter(Context context, List<AreaInfo> list) {
   this.list = list;
  }
  @Override
  public int getCount() {
   return list.size();
  }
  @Override
  public Object getItem(int position) {
   return list.get(position);
  }
  @Override
  public long getItemId(int position) {
   return 0;
  }
  @Override
  public View getView(int position, View convertView, ViewGroup parent) {
   ViewHolder viewHolder = null;
   if (convertView==null){
    convertView = LayoutInflater.from(getContext()).inflate(R.layout.area_list_item,parent,false);
    viewHolder = new ViewHolder();
    viewHolder.textView = (TextView) convertView.findViewById(android.R.id.text1);
    convertView.setTag(viewHolder);
   }
   viewHolder = (ViewHolder) convertView.getTag();
   AreaInfo item = (AreaInfo) list.get(position);
   viewHolder.textView.setText(item.getAreaName());
   if (lastPosition<position&&lastPosition!=0){
    ObjectAnimator.ofFloat(convertView,"translationY",convertView.getHeight()*2,0).setDuration(500).start();
   }
   lastPosition = position;
   return convertView;
  }
  class ViewHolder{
   TextView textView;
  }
 }

很常见的一个Adapter写法，只是在getView当中获取到了要显示的view，通过
ObjectAnimator.ofFloat(convertView,”translationY”,convertView.getHeight()*2,0).setDuration(500).start()为veiw设置了动画，

这里还用了个变量position来区别只有在向上滚动的时候才会有动画。不过我觉得不加position区别的效果也不错，大家可以试试。

其实这样已经实现了效果，接下来顺便提一下Activity对Framgnet中onItemClick的处理。

3、Activity和fragment的交互处理

public class AreaSelectActivity extends AppCompatActivity implements AreaFragment.OnFragmentInteractionListener{
 private Fragment oneFragment;
 private Fragment twoFragment;
 private Map map = new HashMap();
 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_area_select);
  ButterKnife.bind(this);
  //新建第一级地区，parentCode参数为null
  oneFragment = AreaFragment.newInstance("");
  FragmentManager fragmentManager = getSupportFragmentManager();
  fragmentManager.beginTransaction().replace(R.id.content,oneFragment).commit();
 }
 @Override
 public boolean onOptionsItemSelected(MenuItem item) {
  switch (item.getItemId()){
   case android.R.id.home:
    FragmentManager fragmentManager = getSupportFragmentManager();
    if (fragmentManager.getBackStackEntryCount()>0){
     fragmentManager.popBackStack();
    }else{
     finish();
    }
    break;
  }
  return true;
 }
  
 @Override
 public void onFragmentInteraction(AreaInfo areaInfo) {
  if (areaInfo==null){
   return;
  }
  FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
  int level = areaInfo.getLevel();
  switch (level){
   case 1:
    map.put("provId",areaInfo.getId());
    map.put("provName",areaInfo.getAreaName());
    if (areaInfo.isLeaf()){
     Intent intent = new Intent();
     intent.putExtra("addressInfo", (Serializable) map);
     setResult(RESULT_OK,intent);
     finish();
    }else{
     transaction.hide(oneFragment);
     transaction.add(R.id.content,twoFragment=AreaFragment.newInstance(areaInfo.getAreaCode()+"")).addToBackStack(null).commit();
    }
    break;
   case 2:
    map.put("cityId",areaInfo.getId());
    map.put("cityName",areaInfo.getAreaName());
    if (areaInfo.isLeaf()){
     Intent intent = new Intent();
     intent.putExtra("addressInfo", (Serializable) map);
     setResult(RESULT_OK,intent);
     finish();
    }else {
     transaction.hide(twoFragment);
     transaction.add (R.id.content, AreaFragment.newInstance(areaInfo.getAreaCode()+"")).addToBackStack(null).commit();
    }
    break;
   case 3:
    map.put("districtId",areaInfo.getId());
    map.put("districtName",areaInfo.getAreaName());
    Intent intent = new Intent();
    intent.putExtra("addressInfo", (Serializable) map);
    setResult(RESULT_OK,intent);
    finish();
    break;
  }
 }
}

这样仿淘宝地区选择就实现啦！

结语

大家可以自己写测试接口，也可以直接调用我写好的接口： http://123.184.16.19:8008/area/list

源码提供给大家参考：Android仿淘宝地区选择

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