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我们来实现这样的一个小Demo，联系人的快速检索功能，左侧带有字母快速定位，滑动列表时字母相继切换的效果。那么我们来看看实现的Demo，显而易见，这是使用列表控件，而我使用的是ListView控件。至于ListView的一些用法，您可以看这博主的这篇文章ListView使用技巧、优化和用法拓展，掌握ListView，这篇文章我们就不说明它的使用姿势了：
- 源码下载：
- CSDN资源链接：联系人列表（右侧带首字母检索、分类和快速定位）
- GitHub下载地址
效果图
想来想去，我就搞了个王者荣耀的英雄名称来作为我们的联系人。因为模拟器上也没有联系人，也懒得搞，手机的话这个真实的联系人也就不放出来，这也是个人隐私嘛。搞这么多英雄的名字还挺累的，大家将就着看，其实原理都一样。所以，这不是我们的关键，重要的是如何实现这种效果呢？
思路及实现
一、左侧字母检索器
左边是一个自定义View，通过获得屏幕的高度，将26个字母逐一从上往下绘制。通过点击事件绘制不同的颜色，再通过监听右边列表的滑动检索字母选择器中的相对应字母下标，然后绘制改变字母的颜色。
二、列表显示字母分类
列表添加数据，主要说一下头部的字母分类实现。通过获取汉字的原拼音，再检索出首字母。在适配器中判断当前字母是否与前一个字母相同。相同则归类，不相同则分类。
三、中间的字母提示
这个应该是最简单的了，在我们的自定义View里通过接口回调获取点击或滑动切换时所显示的字母，然后在设置到一个TextView上，通过定时器将它延迟隐藏。
大致思路就是这样了，其实自己使劲的想一想，还是可以实现出这样的效果的，也不是特别难。思路讲完了，那么我们就上代码吧，由于代码比较多，所以这里只贴比较核心的地方来看看，若有需要请到我的Github上查看完整的项目。
一、左侧字母检索器
/**
* @Created by xww.
* @Creation time 2018/8/18.
*/
public class ContactIndexView extends View {
private int mRealWidth;
private int mRealHeight;
private int mWidth;
private int mHeight;
private int mEachHeight;
private int mTouchIndex = 0;
private Paint mPaint;
private Rect mRect;
private onShowLetterListener onShowLetterListener = null;
private int colorBackground;
private int colorNormal;
private int colorChecked;
public interface onShowLetterListener {
void showLatter(String letter);
}
public void setOnShowLetter(onShowLetterListener showLetterListener) {
this.onShowLetterListener = showLetterListener;
}
private String[] letters = new String[]{"A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P",
"Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"};
@TargetApi(Build.VERSION_CODES.M)
private void init() {
EventBus.getDefault().register(this);
colorBackground = getContext().getResources().getColor(R.color.colorDivider, null);
colorNormal = getContext().getResources().getColor(R.color.colorWhite, null);
colorChecked = getContext().getResources().getColor(R.color.colorPrimaryDark, null);
mRect = new Rect();
mPaint = new Paint();
mPaint.setStrokeWidth(3f);
mPaint.setAntiAlias(true);
mPaint.setTextSize(38f);
}
public ContactIndexView(Context context, @Nullable AttributeSet attrs) {
super(context, attrs);
init();
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
final int widthMode = MeasureSpec.getMode(widthMeasureSpec);
final int widthSize = MeasureSpec.getSize(widthMeasureSpec);
final int heightMode = MeasureSpec.getMode(heightMeasureSpec);
final int heightSize = MeasureSpec.getSize(heightMeasureSpec);
switch (widthMode) {
case MeasureSpec.UNSPECIFIED:
case MeasureSpec.AT_MOST:
break;
case MeasureSpec.EXACTLY:
mRealWidth = widthSize;
break;
}
switch (heightMode) {
case MeasureSpec.UNSPECIFIED:
case MeasureSpec.AT_MOST:
break;
case MeasureSpec.EXACTLY:
mRealHeight = heightSize;
break;
}
setMeasuredDimension(mRealWidth, mRealHeight);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.drawColor(colorBackground);
mWidth = canvas.getWidth();
mHeight = canvas.getHeight() - getStatusbarHeight();
mEachHeight = mHeight / letters.length;
for (int i = 0; i < letters.length; i++) {
final String _latter = letters[i];
mPaint.getTextBounds(_latter, 0, 1, mRect);
final int letterWidth = mRect.width();
final int letterHeight = mRect.height();
if (mTouchIndex == i) {
mPaint.setColor(colorChecked);
} else {
mPaint.setColor(colorNormal);
}
canvas.drawText(_latter, mWidth / 2 - letterWidth / 2, (i + 1) * mEachHeight - letterHeight / 2, mPaint);
}
}
@SuppressLint("ClickableViewAccessibility")
@Override
public boolean onTouchEvent(MotionEvent event) {
final int y = (int) event.getY();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
refreshLetterIndex(y);
break;
case MotionEvent.ACTION_MOVE:
refreshLetterIndex(y);
break;
}
return true;
}
@Subscribe
public void onListScrollEvent(ScrollEvent event) {
if (event.isLast()) {
return;
}
for (int i = 0; i < letters.length; i++) {
if (event.getLetter().equals(letters[i])) {
mTouchIndex = i;
invalidate();
return;
}
}
}
private void refreshLetterIndex(int y) {
//y坐标 / 每个字母高度 = 当前字母下标
int index = y / mEachHeight;
if (index != mTouchIndex) {
mTouchIndex = index;
//回调选中的字母
if (onShowLetterListener != null) {
onShowLetterListener.showLatter(letters[mTouchIndex]);
}
invalidate();
}
}
private int getStatusbarHeight() {
int resId = getContext().getResources().getIdentifier("status_bar_height", "dimen", "android");
return resId > 0 ? getContext().getResources().getDimensionPixelSize(resId) : 0;
}
}
代码挺长的，最重要的是计算字母所在的x，y坐标，坐标计算准了，才可以绘制到控件的中心去，否则你会发现字母将会偏右或偏左等，显示效果比较难看。
final String _latter = letters[i];
mPaint.getTextBounds(_latter, 0, 1, mRect);
final int letterWidth = mRect.width();
final int letterHeight = mRect.height();这段代码片段，它主要是给文本绘制了一个边框，然后我们从边框的宽、高间接得到文本的宽和高。
二、列表显示字母分类
/**
* @Created by xww.
* @Creation time 2018/8/18.
*/
public class MainActivity extends AppCompatActivity {
private ListView mListView;
private ContactIndexView mIndexView;
private TextView mShowTextView;
private CountDownTimer mCountDownTimer;
private ContactAdapter mAdapter;
private ArrayList<Contact> mContacts;
private String mLetter;
private static final String[] NAME = new String[]{
"露娜", "李白", "韩信", "太乙真人", "李元芳", "阿珂", "夏侯惇", "关羽", "张飞", "刘备", "貂蝉", "吕布", "王昭君", "武则天",
"百里守约", "百里玄策", "司马懿", "孙策", "干将莫邪", "裴擒虎", "张良", "诸葛亮", "达摩", "蒙奇", "曹操", "钟馗", "钟无艳",
"程咬金", "米莱狄", "狄仁杰", "后羿", "大乔", "小乔", "刘邦", "杨玉环", "马可波罗", "狂铁", "苏烈", "赵云", "公孙离", "鬼谷子",
"成吉思汗", "哪吒", "杨戬", "嬴政", "女娲", "周瑜", "弈星", "扁鹊", "甄姬墨子", "高渐离", "亚瑟", "姜子牙", "宫本武藏",
"牛魔", "庄周", "蔡文姬", "黄忠", "鲁班七号", "铠", "妲己", "白起", "安其拉", "不知火舞", "芈月", "项羽", "刘禅", "橘右京",
"兰陵王", "典韦", "元歌", "明世隐", "雅典娜", "娜可露露", "东皇太一", "花木兰", "孙尚香", "孙膑", "虞姬", "孙悟空", "老夫子"
};
@SuppressWarnings("unchecked")
private <T extends View> T $(int id) {
View view = findViewById(id);
return (T) view;
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initView();
}
private void initView() {
mListView = $(R.id.list_contact);
mIndexView = $(R.id.view_contact);
mShowTextView = $(R.id.tv_show_letter);
initData();
initListener();
}
private void initData() {
mContacts = new ArrayList<>();
for (String name : NAME) {
mContacts.add(new Contact(name));
}
Collections.sort(mContacts, (o1, o2) -> o1.getPinyin().compareTo(o2.getPinyin()));
mAdapter = new ContactAdapter(mContacts);
mListView.setAdapter(mAdapter);
}
@SuppressWarnings("UnusedAssignment")
private void initListener() {
mIndexView.setOnShowLetter(letter -> {
mShowTextView.setText(letter);
mLetter = letter;
if (mCountDownTimer == null) {
mCountDownTimer = new CountDownTimer(1500, 500) {
@Override
public void onTick(long millisUntilFinished) {
mShowTextView.setVisibility(View.VISIBLE);
}
@Override
public void onFinish() {
mShowTextView.setVisibility(View.INVISIBLE);
if (mCountDownTimer != null) {
mCountDownTimer.cancel();
mCountDownTimer = null;
}
}
}.start();
} else {
mCountDownTimer.start();
}
for (int i = 0; i < mContacts.size(); i++) {
final String letterName = mContacts.get(i).getPinyin().substring(0, 1);
if (letterName.equals(mLetter)) {
mListView.setSelection(i);
return;
}
}
});
mListView.setOnScrollListener(new AbsListView.OnScrollListener() {
@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {}
@Override
public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
String letter = mContacts.get(firstVisibleItem).getPinyin().substring(0, 1);
boolean isLast = false;
if (firstVisibleItem + visibleItemCount == totalItemCount) {
isLast = true;
}
EventBus.getDefault().post(new ScrollEvent(letter, isLast));
}
});
}
}我们的Activity没什么好说的，就是添加数据和一些监听事件。主要注意列表的滑动监听，我们要判断是否已经滑动到了最底部，如果在列表最底部，我们不再处理滑动监听事件。其实，我之前用的是自己随机组的一些名字，发现有点影响美观，所以就换了。
三、列表适配器的逻辑代码
/**
* @Created by xww.
* @Creation time 2018/8/18.
*/
public class ContactAdapter extends BaseAdapter {
private ArrayList<Contact> mContacts;
ContactAdapter(ArrayList<Contact> contacts) {
this.mContacts = contacts;
}
@Override
public int getCount() {
return mContacts == null ? 0 : mContacts.size();
}
@Override
public Object getItem(int position) {
return mContacts.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder;
if (convertView == null) {
convertView = LayoutInflater.from(parent.getContext()).inflate(R.layout.adapter_contact, parent, false);
holder = new ViewHolder(convertView);
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
final String name = mContacts.get(position).getName();
final String pinyin = mContacts.get(position).getPinyin().substring(0, 1);
if (position == 0) {
holder.tvPinYin.setVisibility(View.VISIBLE);
} else {
final String prePinyin = mContacts.get(position - 1).getPinyin().substring(0, 1);
if (pinyin.equals(prePinyin)) {
holder.tvPinYin.setVisibility(View.GONE);
} else {
holder.tvPinYin.setVisibility(View.VISIBLE);
}
}
holder.tvName.setText(name);
holder.tvPinYin.setText(pinyin);
return convertView;
}
private static class ViewHolder {
private TextView tvName;
private TextView tvPinYin;
ViewHolder(View itemView) {
tvName = itemView.findViewById(R.id.tv_name);
tvPinYin = itemView.findViewById(R.id.tv_pinyin);
}
}
}我们看关键代码：
if (position == 0) {
holder.tvPinYin.setVisibility(View.VISIBLE);
} else {
final String prePinyin = mContacts.get(position - 1).getPinyin().substring(0, 1);
if (pinyin.equals(prePinyin)) {
holder.tvPinYin.setVisibility(View.GONE);
} else {
holder.tvPinYin.setVisibility(View.VISIBLE);
}
}这段是实现列表头部的字母分类的，我们知道第一个字母永远不会重复，而从第二个字母开始，我们判断是否与前一个字母一样来决定字母的显示与否。
四、汉字转拼音的一个工具类
/**
* @Created by xww.
* @Creation time 2018/8/18.
*/
final class PinYinUtils {
public static String getPinYin(String hanzi) {
StringBuilder pinyin = new StringBuilder();
HanyuPinyinOutputFormat format = new HanyuPinyinOutputFormat();
format.setCaseType(HanyuPinyinCaseType.UPPERCASE);
format.setToneType(HanyuPinyinToneType.WITHOUT_TONE);
char[] arr = hanzi.toCharArray();
for (char anArr : arr) {
if (Character.isWhitespace(anArr)) continue;
if (anArr > 127) {
try {
String[] pinyinArr = PinyinHelper.toHanyuPinyinStringArray(anArr, format);
if (pinyinArr != null) {
pinyin.append(pinyinArr[0]);
} else {
pinyin.append(anArr);
}
} catch (BadHanyuPinyinOutputFormatCombination e) {
e.printStackTrace();
pinyin.append(anArr);
}
} else {
pinyin.append(anArr);
}
}
return pinyin.toString();
}
}
这个工具栏比较固定 ，那么所有的关键是的代码基本就这些了。这是我个人写的一个联系人的Demo，个人认为界面还不错，哈哈。
