【Android - 框架】之可悬浮列表StickyHeadersRecyclerView

        这是timehop的GitHub上发表的一个控件框架，大家可以去参考它的【GitHub】。

        这里先贴出GitHub上提供的效果图：



        要使用这个框架，我们需要首先导入它的依赖：

compile 'com.timehop.stickyheadersrecyclerview:library:0.4.3'
compile 'com.android.support:recyclerview-v7:24.0.0'        这里需要说明的是，这个框架要求SDK的最小版本不能低于14；另外，这个框架在2016年4月之后就不再更新维护了。

        下面让我们来看一下它的使用方式：

（1）在布局文件中，我们仍然使用RecyclerView：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent">

<android.support.v7.widget.RecyclerView
android:id="@+id/rv"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</RelativeLayout>（2）MainActivity中的代码如下：

package com.example.itgungnir.teststickyheadersrecyclerview;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import android.widget.Toast;

import com.timehop.stickyheadersrecyclerview.StickyRecyclerHeadersAdapter;
import com.timehop.stickyheadersrecyclerview.StickyRecyclerHeadersDecoration;
import com.timehop.stickyheadersrecyclerview.StickyRecyclerHeadersTouchListener;

public class MainActivity extends AppCompatActivity {
private RecyclerView rv;

private AnimalsHeadersAdapter adapter;
private StickyRecyclerHeadersDecoration headersDecor;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
rv = (RecyclerView) findViewById(R.id.rv);
}

@Override
protected void onResume() {
super.onResume();
initView();
initEvent();
}

private void initView() {
// 为RecyclerView设置适配器
adapter = new AnimalsHeadersAdapter();
adapter.addAll(getDummyDataSet());
rv.setAdapter(adapter);
// 为RecyclerView添加LayoutManager
final LinearLayoutManager layoutManager = new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false);
rv.setLayoutManager(layoutManager);
// 为RecyclerView添加Decorator装饰器
// 为RecyclerView中的Item添加Header头部（自动获取头部ID，将相邻的ID相同的聚合到一起形成一个Header）
headersDecor = new StickyRecyclerHeadersDecoration(adapter);
rv.addItemDecoration(headersDecor);
// 为RecyclerView添加Item之间的分隔线
rv.addItemDecoration(new DividerDecoration(this));
}

private void initEvent() {
// 为RecyclerView添加普通Item的点击事件（点击Header无效）
rv.addOnItemTouchListener(new RecyclerItemClickListener(this, new RecyclerItemClickListener.OnItemClickListener() {
@Override
public void onItemClick(View view, int position) {
Toast.makeText(MainActivity.this, adapter.getItem(position) + " Clicked", Toast.LENGTH_SHORT).show();
}
}));
// 为RecyclerView添加Header的点击事件
StickyRecyclerHeadersTouchListener touchListener = new StickyRecyclerHeadersTouchListener(rv, headersDecor);
touchListener.setOnHeaderClickListener(new StickyRecyclerHeadersTouchListener.OnHeaderClickListener() {
@Override
public void onHeaderClick(View header, int position, final long headerId) {
Toast.makeText(MainActivity.this, "Header position: " + position + ", id: " + headerId, Toast.LENGTH_SHORT).show();
}
});
rv.addOnItemTouchListener(touchListener);
}

// 获取RecyclerView中展示的数据源
private String[] getDummyDataSet() {
return getResources().getStringArray(R.array.animals);
}

// StickyHeadersRecyclerView的适配器类
private class AnimalsHeadersAdapter extends AnimalAdapter<RecyclerView.ViewHolder> implements StickyRecyclerHeadersAdapter<RecyclerView.ViewHolder> {
@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.listitem_normal, parent, false);
return new RecyclerView.ViewHolder(view) {
};
}

@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
TextView textView = (TextView) holder.itemView;
textView.setText(getItem(position));
}

// 获取当前Item的首字母，按照首字母将相邻的Item聚集起来并添加统一的头部
@Override
public long getHeaderId(int position) {
return getItem(position).charAt(0);
}

// 获取头部布局
@Override
public RecyclerView.ViewHolder onCreateHeaderViewHolder(ViewGroup parent) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.listitem_header, parent, false);
return new RecyclerView.ViewHolder(view) {
};
}

// 为头部布局中的控件绑定数据
@Override
public void onBindHeaderViewHolder(RecyclerView.ViewHolder holder, int position) {
final TextView textView = (TextView) holder.itemView;
textView.setText(String.valueOf(getItem(position).charAt(0)));
}
}
}

（3）AnimalAdapter类中的代码：
import android.support.v7.widget.RecyclerView;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;

/**
* RecyclerView的适配器
*/
public abstract class AnimalAdapter<VH extends RecyclerView.ViewHolder> extends RecyclerView.Adapter<VH> {
private ArrayList<String> items = new ArrayList<String>();

public AnimalAdapter() {
setHasStableIds(true);
}

public void add(String object) {
items.add(object);
notifyDataSetChanged();
}

public void add(int index, String object) {
items.add(index, object);
notifyDataSetChanged();
}

public void addAll(Collection<? extends String> collection) {
if (collection != null) {
items.addAll(collection);
notifyDataSetChanged();
}
}

public void addAll(String... items) {
addAll(Arrays.asList(items));
}

public void clear() {
items.clear();
notifyDataSetChanged();
}

public void remove(String object) {
items.remove(object);
notifyDataSetChanged();
}

public String getItem(int position) {
return items.get(position);
}

@Override
public long getItemId(int position) {
return getItem(position).hashCode();
}

@Override
public int getItemCount() {
return items.size();
}
}（4）RecyclerItemClickListener类中的代码：
import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.View;

public class RecyclerItemClickListener implements RecyclerView.OnItemTouchListener {
private OnItemClickListener mListener;
private GestureDetector mGestureDetector;

public RecyclerItemClickListener(Context context, OnItemClickListener listener) {
mListener = listener;
mGestureDetector = new GestureDetector(context, new GestureDetector.SimpleOnGestureListener() {
@Override
public boolean onSingleTapUp(MotionEvent e) {
return true;
}
});
}

@Override
public boolean onInterceptTouchEvent(RecyclerView view, MotionEvent e) {
View childView = view.findChildViewUnder(e.getX(), e.getY());
if (childView != null && mListener != null && mGestureDetector.onTouchEvent(e)) {
mListener.onItemClick(childView, view.getChildAdapterPosition(childView));
}
return false;
}

@Override
public void onTouchEvent(RecyclerView view, MotionEvent motionEvent) {
}

@Override
public void onRequestDisallowInterceptTouchEvent(boolean disallowIntercept) {
// do nothing
}

public interface OnItemClickListener {
void onItemClick(View view, int position);
}
}