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);
 }
 }