Android仿微信联系人列表字母侧滑控件

protected void onDraw(Canvas canvas) {
  super.onDraw(canvas);
  int height = getHeight();// 获取对应高度
  int width = getWidth(); // 获取对应宽度
  int singleHeight = height / getData().size();// 获取每一个字母的高度

  for (int i = 0; i < getData().size(); i++) {
   mPaint.setColor(getLetterColor());//绘制字母的颜色
   mPaint.setTypeface(Typeface.DEFAULT);
   mPaint.setAntiAlias(true);
   mPaint.setTextSize(singleHeight);
   // 如果是选中的状态
   if (i == mPosition) {
    mPaint.setColor(getLetterPressedColor());
    mPaint.setFakeBoldText(true);
   }
   // x坐标等于总体宽度中间的位置减去字符串宽度的一半.
   float xPos = width / 2 - mPaint.measureText(getData().get(i)) / 2;
   float yPos = singleHeight * i + singleHeight;
   canvas.drawText(getData().get(i), xPos, yPos, mPaint);
   mPaint.reset();// 重置画笔
  }

 }

 @Override
 public boolean dispatchTouchEvent(MotionEvent event) {
  final int action = event.getAction();
  final float y = event.getY();// 点击y坐标
  final int lastPosition = mPosition;//记录上一次选中字母的位置
  final int position = (int) (y / getHeight() * getData().size());// 点击y坐标所占总高度的比例*b数组的长度就等于点击b中的个数.

  switch (action) {
   //当手指离开
   case MotionEvent.ACTION_UP:
   //设置侧滑控件的背景色
    setBackgroundColor(getBackgroundNormalColor());
    mPosition = -1;
    invalidate();

    if (getOnTouchLetterListener() != null) {
    //回调事件，告知当前手指已经离开当前区域
     getOnTouchLetterListener().onTouchOutside();
    }

    break;

   default:
   //更改当字母为选中状态时控件的背景色
    setBackgroundColor(getBackgroundPressedColor());
    //如果选中字母的位置不等于上一次选中的位置
    if (lastPosition != position) {
     if (position >= 0 && position < getData().size()) {
      if (getOnTouchLetterListener() != null) {
      //回调事件，返回当前选中的字母
       getOnTouchLetterListener().onTouchLetter(getData().get(position));
      }
      mPosition = position;
      invalidate();
     }
    }

    break;
  }
  return true;
 }

 public interface OnTouchLetterListener {

  /**
   * 当接触到某个key的时候会调用;
   * @param s
   */
  void onTouchLetter(String s);

  /**
   * 当离开控件可触摸区域时会调用;
   */
  void onTouchOutside();
 }

public abstract class SimpleAdapter<T> extends BaseAdapter {

 protected Context mContext;
 protected List<T> mData;

 public SimpleAdapter(){}

 public SimpleAdapter(Context context, List<T> data){
  init(context, data);
 }

 public void init(Context context, List<T> data){
  this.mContext = context;
  this.mData = data;
 }

 @Override
 public int getCount() {
  return mData.size();
 }

 @Override
 public T getItem(int position) {
  if(checkPositionIsOutOfRange(position)){
   return null;
  }
  return mData.get(position);
 }

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

 @Override
 public abstract View getView(int position, View convertView, ViewGroup parent);

 public void refresh(List<T> data){
  if(data == null){
   this.mData.clear();
  }else{
   this.mData = data;
  }
  notifyDataSetChanged();
 }

 public boolean checkPositionIsOutOfRange(int position){
  if(0 <= position && position < mData.size()){
   return false;
  }
  return true;
 }

 public Context getContext(){
  return mContext;
 }

 public List<T> getData(){
  return mData;
 }
}

public abstract class SortAdapter<K extends SortKey, V, VH_G extends ViewHolder, VH_C extends ViewHolder> extends SimpleAdapter<Object> {

 public final static int VIEW_TYPE_GROUP = 0;
 public final static int VIEW_TYPE_CHILD = 1;

 private HashMap<SortKey, Integer> mKeyIndex = new HashMap<>();

 public SortAdapter(Context context, Map<K, List<V>> map) {
  init(context, convertMapToList(map));
 }

 public SortAdapter(Context context, List<Object> list) {
  init(context, list);
 }

 /**
  * 转换分组数据为List,并且更新键值的索引
  * @param map
  * @return
  */
 public List<Object> convertMapToList(Map<K, List<V>> map) {
  List<Object> mData = new ArrayList<>();
  mKeyIndex.clear();
  for (Map.Entry<K, List<V>> entry : map.entrySet()) {
   mData.add(entry.getKey());
   mKeyIndex.put(entry.getKey(), mData.size() - 1);
   for (V v : entry.getValue()) {
    mData.add(v);
   }
  }
  return mData;
 }

 public void refresh(Map<K, List<V>> map) {
  super.refresh(convertMapToList(map));
 }

 @Override
 public void refresh(List<Object> data) {
  super.refresh(data);
  mKeyIndex.clear();
 }

 /**
  * 得到键值的索引值
  * @param k
  * @return
  */
 public int getKeyIndex(K k){
  Integer integer = mKeyIndex.get(k);
  if(integer == null){
   return getKeyIndexFromList(k);
  }
  return integer;
 }

 public int getKeyIndexFromList(K k){
  for(int i = 0; i < getCount(); i++){
   Object obj = getItem(i);
   if(obj != null && obj instanceof SortKey){
    if(obj.equals(k)){
     mKeyIndex.put(k, i);
     return i;
    }
   }
  }
  return -1;
 }

 @Override
 public int getItemViewType(int position) {
  Object obj = getItem(position);

  if (obj instanceof SortKey) {
   return VIEW_TYPE_GROUP;
  }
  return VIEW_TYPE_CHILD;
 }

 @Override
 public int getViewTypeCount() {
  return 2;
 }

 @Override
 public int getCount() {
  return mData.size();
 }

 @Override
 public Object getItem(int position) {
  if (0 <= position && position < mData.size()) {
   return mData.get(position);
  }
  return null;
 }

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

 @Override
 public View getView(int position, View convertView, ViewGroup parent) {

  int viewType = getItemViewType(position);

  View view = null;
  Object obj = getItem(position);
  switch (viewType) {
   case VIEW_TYPE_GROUP:
    view = getGroupView((K)obj, position, convertView, parent);
    break;
   case VIEW_TYPE_CHILD:
    view = getChildView((V)obj, position, convertView, parent);
    break;
  }
  return view;
 }

 public View getGroupView(K key, int position, View convertView, ViewGroup parent){
  VH_G vh;
  if(convertView == null){
   convertView = LayoutInflater.from(mContext).inflate(getGroupLayoutId(), null);
   vh = onCreateGroupViewHolder(convertView, parent);
   convertView.setTag(vh);
  }else{
   vh = (VH_G)convertView.getTag();
  }

  onBindGroupViewHolder(vh, key, position);
  return convertView;
 }

 public View getChildView(V value, int position, View convertView, ViewGroup parent){
  VH_C vh;
  if(convertView == null){
   convertView = LayoutInflater.from(mContext).inflate(getChildLayoutId(), null);
   vh = onCreateChildViewHolder(convertView, parent);
   convertView.setTag(vh);
  }else{
   vh = (VH_C)convertView.getTag();
  }

  onBindChildViewHolder(vh, value, position);
  return convertView;
 }

 public abstract @LayoutRes int getGroupLayoutId();

 public abstract VH_G onCreateGroupViewHolder(View convertView, ViewGroup parent);

 public abstract void onBindGroupViewHolder(VH_G vh, K key, int position);

 public abstract @LayoutRes int getChildLayoutId();

 public abstract VH_C onCreateChildViewHolder(View convertView, ViewGroup parent);

 public abstract void onBindChildViewHolder(VH_C vh, V value, int position);

 public interface SortKey {
 }

 public static class ViewHolder{

  public View mParent;
  public ViewHolder(View parent){
   mParent = parent;
  }

  public View findViewById(@IdRes int id){
   return mParent.findViewById(id);
  }
 }