class SampleGroupBean implements BaseExpandableRecyclerViewAdapter.BaseGroupBean<SampleChildBean> {
    @Override
    public int getChildCount() {
        return mList.size();
    }

    // whether this group is expandable
    @Override
    public boolean isExpandable() {
        return getChildCount() > 0;
    }
  
  	@Override
    public SampleChildBean getChildAt(int index) {
        return mList.size() <= index ? null : mList.get(index);
    }
}

public class SampleChildBean {
}

static class GroupVH extends BaseExpandableRecyclerViewAdapter.BaseGroupViewHolder {
    GroupVH(View itemView) {
        super(itemView);
    }

    // this method is used for partial update.Which means when expand status changed,only a part of this view need to invalidate
    @Override
    protected void onExpandStatusChanged(RecyclerView.Adapter relatedAdapter, boolean isExpanding) {
      // 1.只更新左侧展开、闭合箭头
      foldIv.setImageResource(isExpanding ? R.drawable.ic_arrow_expanding : R.drawable.ic_arrow_folding);
      
      // 2.默认刷新整个Item
      relatedAdapter.notifyItemChanged(getAdapterPosition());
    }
}

static class ChildVH extends RecyclerView.ViewHolder {
    ChildVH(View itemView) {
        super(itemView);
    }
}

// !!注意这里继承时候使用的泛型，分别为上面提到的Bean和ViewHolder
public class SampleAdapter extends BaseExpandableRecyclerViewAdapter
<SampleGroupBean, SampleChildBean, SampleAdapter.GroupVH, SampleAdapter.ChildVH>

    @Override
    public int getGroupCount() {
        // 父节点个数
    }

    @Override
    public GroupBean getGroupItem(int groupIndex) {
        // 获取父节点
    }

    @Override
    public GroupVH onCreateGroupViewHolder(ViewGroup parent, int groupViewType) {
    }

    @Override
    public ChildVH onCreateChildViewHolder(ViewGroup parent, int childViewType) {
    }

    @Override
    public void onBindGroupViewHolder(GroupVH holder, SampleGroupBean sampleGroupBean, boolean isExpand) {
    }

    @Override
    public void onBindChildViewHolder(ChildVH holder, SampleGroupBean sampleGroupBean, SampleChildBean sampleChildBean) {
    }
}

protected int getGroupType(GroupBean groupBean) {
    return 0;
}

abstract public GroupViewHolder onCreateGroupViewHolder(ViewGroup parent, int groupViewType);
    
protected int getChildType(GroupBean groupBean, ChildBean childBean) {
    return 0;
}

abstract public ChildViewHolder onCreateChildViewHolder(ViewGroup parent, int childViewType);

adapter.setEmptyViewProducer(new ViewProducer() {
    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent) {
        View emptyView = LayoutInflater.from(parent.getContext()).inflate(R.layout.empty, parent, false);
        return new DefaultEmptyViewHolder(emptyView);
    }

    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder holder) {
    }
});

adapter.setEmptyViewProducer(new ViewProducer() {
    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent) {
        View emptyView = LayoutInflater.from(parent.getContext()).inflate(R.layout.header, parent, false);
        return new DefaultEmptyViewHolder(emptyView);
    }

    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder holder) {
    }
},false);

public interface ExpandableRecyclerViewOnClickListener<GroupBean extends BaseGroupBean, ChildBean> {

        /**
         * 长按时的操作
         *
         * @param groupItem
         * @return
         */
        boolean onGroupLongClicked(GroupBean groupItem);

        /**
         * 在可展开group被点击的时候触发的回调，返回布尔值表示是否拦截该操作
         *
         * @param groupItem
         * @param isExpand
         * @return true 使点击无效。false 正常执行展开、闭合操作。
         */
        boolean onInterceptGroupExpandEvent(GroupBean groupItem, boolean isExpand);

        /**
         * 点击GroupView时的操作(该Group的isExpandable返回false才会触发这个回调)
         *
         * @param groupItem
         */
        void onGroupClicked(GroupBean groupItem);

        /**
         * 点击子View时的操作
         *
         * @param groupItem
         * @param childItem
         */
        void onChildClicked(GroupBean groupItem, ChildBean childItem);
    }

private static final int TYPE_EMPTY = ViewProducer.VIEW_TYPE_EMPTY;
private static final int TYPE_HEADER = ViewProducer.VIEW_TYPE_HEADER;
private static final int TYPE_GROUP = ViewProducer.VIEW_TYPE_EMPTY >> 2;
private static final int TYPE_CHILD = ViewProducer.VIEW_TYPE_EMPTY >> 3;
private static final int TYPE_MASK = TYPE_GROUP | TYPE_CHILD | TYPE_EMPTY | TYPE_HEADER;

// 通过getItemView判断类型，这里默认是使用上面定义的MASK，可以重载使Group和Child中再划分子类，但是不允许和TYPE_MASK冲突，否则会报Exception
@Override
public final int getItemViewType(int position) {
    if (mIsEmpty) {
        return position == 0 && mShowHeaderViewWhenEmpty ? TYPE_HEADER : TYPE_EMPTY;
    }
    if (position == 0 && mHeaderViewProducer != null) {
        return TYPE_HEADER;
    }
    int[] coord = translateToDoubleIndex(position);
    GroupBean groupBean = getGroupItem(coord[0]);
    if (coord[1] < 0) {
        int groupType = getGroupType(groupBean);
        if ((groupType & TYPE_MASK) == 0) {
            return groupType | TYPE_GROUP;
        } else {
            throw new IllegalStateException(
                String.format(Locale.getDefault(), "GroupType [%d] conflits with MASK [%d]", groupType, TYPE_MASK));
        }
    } else {
        int childType = getChildType(groupBean, groupBean.getChildAt(coord[1]));
        if ((childType & TYPE_MASK) == 0) {
            return childType | TYPE_CHILD;
        } else {
            throw new IllegalStateException(
                String.format(Locale.getDefault(), "ChildType [%d] conflits with MASK [%d]", childType, TYPE_MASK));
        }
    }
}

@Override
public final RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    switch (viewType) {
        case TYPE_EMPTY:
            return mEmptyViewProducer.onCreateViewHolder(parent);
        case TYPE_HEADER:
            return mHeaderViewProducer.onCreateViewHolder(parent);
        case TYPE_CHILD:
            return onCreateChildViewHolder(parent, viewType ^ TYPE_CHILD);
        case TYPE_GROUP:
            return onCreateGroupViewHolder(parent, viewType ^ TYPE_GROUP);
        default:
            throw new IllegalStateException(
                String.format(Locale.getDefault(), "Illegal view type : viewType[%d]", viewType));
    }
}

@Override
public final void onBindViewHolder(final RecyclerView.ViewHolder holder, int position) {
    onBindViewHolder(holder, position, null);
}

@Override
public final void onBindViewHolder(RecyclerView.ViewHolder holder, int position, List<Object> payloads) {
    switch (holder.getItemViewType() & TYPE_MASK) {
        case TYPE_EMPTY:
            mEmptyViewProducer.onBindViewHolder(holder);
            break;
        case TYPE_HEADER:
            mHeaderViewProducer.onBindViewHolder(holder);
            break;
        case TYPE_CHILD:
            final int[] childCoord = translateToDoubleIndex(position);
            GroupBean groupBean = getGroupItem(childCoord[0]);
            bindChildViewHolder((ChildViewHolder) holder, groupBean, groupBean.getChildAt(childCoord[1]), payloads);
            break;
        case TYPE_GROUP:
            bindGroupViewHolder((GroupViewHolder) holder,
                getGroupItem(translateToDoubleIndex(position)[0]), payloads);
            break;
        default:
            throw new IllegalStateException(
                String.format(Locale.getDefault(), "Illegal view type : position [%d] ,itemViewType[%d]", position, holder.getItemViewType()));
    }
}

private Set<GroupBean> mExpandGroupSet;

protected void bindGroupViewHolder(final GroupViewHolder holder, final GroupBean groupBean, List<Object> payload) {
  	// ...
    if (!groupBean.isExpandable()) {
      // ...
    } else {
        holder.itemView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                final boolean isExpand = mExpandGroupSet.contains(groupBean);
                if (mListener == null || !mListener.onInterceptGroupExpandEvent(groupBean, isExpand)) {
                final int adapterPosition = holder.getAdapterPosition();
                holder.onExpandStatusChanged(BaseExpandableRecyclerViewAdapter.this, !isExpand);
                    if (isExpand) {
                        mExpandGroupSet.remove(groupBean);
                        notifyItemRangeRemoved(adapterPosition + 1, groupBean.getChildCount());
                    } else {
                        mExpandGroupSet.add(groupBean);
                        notifyItemRangeInserted(adapterPosition + 1, groupBean.getChildCount());
                    }
                }
            }
        });
    }
  	// 子类实现
    onBindGroupViewHolder(holder, groupBean, isGroupExpand(groupBean));
}

private static final Object EXPAND_PAYLOAD = new Object();

// 局部刷新时调用的接口(已封装好，用户无需调用)
notifyItemChanged(position, EXPAND_PAYLOAD);

// 处理payload
protected void bindGroupViewHolder(final GroupViewHolder holder, final GroupBean groupBean, List<Object> payload) {
    if (payload != null && payload.size() != 0) {
        if (payload.contains(EXPAND_PAYLOAD)) {
          	// holder方法有抽象方法，在此方法中实现具体的展开、闭合逻辑
            holder.onExpandStatusChanged(BaseExpandableRecyclerViewAdapter.this, isGroupExpand(groupBean));
            if (payload.size() == 1) {
                return;
            }
        }
    onBindGroupViewHolder(holder, groupBean, isGroupExpand(groupBean), payload);
    return;
    }
}

URL mURL = new URL(url);
httpURLConnection = (HttpURLConnection) mURL.openConnection();
httpURLConnection.setConnectTimeout(15000);
httpURLConnection.setReadTimeout(15000);
httpURLConnection.setRequestMethod("GET");
httpURLConnection.setRequestProperty("Connection", "Keep-Alive");
httpURLConnection.setDoInput(true);
httpURLConnection.connect();

inputStream = httpURLConnection.getInputStream();
int code = httpURLConnection.getResponseCode();
String response = UrlConnManager.convertStreamToString(inputStream);
inputStream.close();

URL mURL = new URL(url);
httpURLConnection = (HttpURLConnection) mURL.openConnection();

httpURLConnection.setConnectTimeout(15000);
httpURLConnection.setReadTimeout(15000);
httpURLConnection.setRequestMethod("POST");
httpURLConnection.setRequestProperty("Connection", "Keep-Alive");
httpURLConnection.setDoInput(true);
//post传递参数时需要开启
httpURLConnection.setDoOutput(true);

//post body
OutputStream outputStream = httpURLConnection.getOutputStream();
StringBuilder sb = new StringBuilder();
for (NameValuePair nameValuePair : paramsList) {
    if (!TextUtils.isEmpty(sb)) {
        sb.append("&");
    }
    sb.append(URLEncoder.encode(nameValuePair.getName(), "UTF-8"));
    sb.append("=");
    sb.append(URLEncoder.encode(nameValuePair.getValue(), "UTF-8"));
}
BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(outputStream, "UTF-8"));
writer.write(sb.toString());
writer.flush();
writer.close();

httpURLConnection.connect();
inputStream = httpURLConnection.getInputStream();
int code = httpURLConnection.getResponseCode();
String response = UrlConnManager.convertStreamToString(inputStream);
inputStream.close();

RequestQueue queue = Volley.newRequestQueue(getApplicationContext());
StringRequest stringRequest = new StringRequest(
    Request.Method.GET,
    "https://www.baidu.com",
    new Response.Listener<String>() {
        @Override
        public void onResponse(String response) {
            Log.d(TAG, "====" + response);
         }
    },
    new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {
        }
    }
);
JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(
    "http://ip.taobao.com/service/getIpInfo.php?ip=59.108.54.37",
    null,
    new Response.Listener<JSONObject>() {
        @Override
        public void onResponse(JSONObject response) {
             IpModel ipModel = new Gson().fromJson(response.toString(), IpModel.class);
             Log.d(TAG, "====ip" + ipModel);
        }
    },
    new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {

        }
    }
);
queue.add(stringRequest);
queue.add(jsonObjectRequest);

okhttp3.Request.Builder requestBuilder = new okhttp3.Request.Builder().url("http://blog.csdn.net/itachi85");
//POST请求需要用FormBody封装请求的参数
requestBuilder.method("GET", null);
okhttp3.Request request = requestBuilder.build();

OkHttpClient okHttpClient = new OkHttpClient();
Call call = okHttpClient.newCall(request);

call.enqueue(new Callback() {
    @Override
    public void onFailure(Call call, IOException e) {

    }

    @Override
    public void onResponse(Call call, okhttp3.Response response) throws IOException {
        Log.d(TAG, "====" + response.body().toString());
    }
});

//POST
public interface IpServiceForPost {
    @FormUrlEncoded
    @POST("{path}/getIpInfo.php")
    Call<IpModel> getIpMsg(@Path("path") String path, @Field("ip") String first);
}

//GET
public interface IpService {
    @GET("{path}/getIpInfo.php")
    Call<IpModel> getIpMsg(@Path("path") String path, @Query("ip") String ip);
}

//其他注解
//Path：地址
//Query(Map)
//Field
//Body 数据传输类型JSON字符串
//Part 单个文件上传
//Header 消息报头


String url = "http://ip.taobao.com/";
Retrofit retrofit = new Retrofit.Builder()
    .baseUrl(url)
    .addConverterFactory(GsonConverterFactory.create())
    .build();
IpService ipService = retrofit.create(IpService.class);
retrofit2.Call<IpModel> call = ipService.getIpMsg("service","59.108.54.37");

// 同步方法使用execute
call.enqueue(new retrofit2.Callback<IpModel>() {
    @Override
    public void onResponse(retrofit2.Call<IpModel> call, retrofit2.Response<IpModel> response) {
        String country = response.body().toString();
        Log.d(TAG, "==== coutry is " + country);
    }

        @Override
        public void onFailure(retrofit2.Call<IpModel> call, Throwable t) {

        }
});

//Messenger的构造方法

// 初始化
Messenger(Handler);

// 从服务端获得IBinder后初始化
Messenger(IBinder);

//服务端
public class MessengerService extends Service{
  	private Messenger mMessenger = new Messenger(new Handler());
  
  	@Override
  	public IBinder onBind(Intent intent){
      	return mMessenger.getBinder();
  	}
}

//客户端
private mMessenger;

public ServiceConnection mConnection = new ServiceConnection(){
  	public void onServiceConnected(ComponentName className,IBinder service){
      	mMessenger = new Messenger(service);
  	}
}

onCreate(){
  	bindService(intent,mConnection,Context.BIND_AUTO_CREATE);
}

Uri userUri = Uri.parse("content://com.dendi.chapter.book.provider/user");
Cursor userCursor = getContentResolver().query(
  	userUri,new String[]{"_id","name","sex"},null,null,null);
while(userCursor.moveToNext()){
 	//print
}

protected void onCreate(Bundle savedInstanceState){
  	setContentView();
  	//显示splashFragment
  
  	getWindow().getDecorView().post(new Runnable(){
      	//渲染主界面，用队列
      	viewStub.inflate();
  	});
  
  	//等时间结束后，取消splashFragment，呈现主界面
}

public boolean dispatchTouchEvent(MotionEvent ev) {
    if (ev.getAction() == MotionEvent.ACTION_DOWN) {
        onUserInteraction();
    }
    if (getWindow().superDispatchTouchEvent(ev)) {
        return true;
    }
    return onTouchEvent(ev);
}

public boolean dispatchTouchEvent(MotionEvent ev) {
    boolean result = false;             // 默认状态为没有消费过

    if (!onInterceptTouchEvent(ev)) {   // 如果没有拦截交给子View
        result = child.dispatchTouchEvent(ev);
    }

    if (!result) {                      // 如果事件没有被消费,询问自身onTouchEvent
        result = onTouchEvent(ev);
    }

    return result;
}

// check for interception
final boolean intercepted;
if (actionMasked == MotionEvent.ACTION_DOWN
                    || mFirstTouchTarget != null) {
    final boolean disallowIntercept = (mGroupFlags & FLAG_DISALLOW_INTERCEPT) != 0;
    if (!disallowIntercept) {
        intercepted = onInterceptTouchEvent(ev);
        ev.setAction(action); // restore action in case it was changed
    } else {
        intercepted = false;
    }
} else {
    // There are no touch targets and this action is not an initial down
    // so this view group continues to intercept touches.
    intercepted = true;
}

public boolean dispatchTouchEvent(MotionEvent event) {

        boolean result = false;

        if (onFilterTouchEventForSecurity(event)) {
            if ((mViewFlags & ENABLED_MASK) == ENABLED && handleScrollBarDragging(event)) {
                result = true;
            }
            //noinspection SimplifiableIfStatement
            ListenerInfo li = mListenerInfo;
            if (li != null && li.mOnTouchListener != null
                    && (mViewFlags & ENABLED_MASK) == ENABLED
                    && li.mOnTouchListener.onTouch(this, event)) {
                result = true;
            }

            if (!result && onTouchEvent(event)) {
                result = true;
            }
        }

        return result;
    }