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() {
}

/**
* Use this factory method to create a new instance of
* this fragment using the provided parameters.
*
* @param param1 Parameter 1.
* @return A new instance of fragment 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;
}

/**
* 处理交互，hide前一个fragment，并且调用addToBackStack让Fragment可以点击back的时候显示前一个fragment
* 如果是第 * 地区则直接返回地区选择数据给上个Activity
* @param areaInfo 被点击的地区信息
*/
@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