Aandroid 首字母索引在一般具有选择联系和城市列表的功能的App中都是非常常见,并且实用性很高。由于之前做的应用真的没有用到过首字母索引的功能,并且android没有提供对应的组件,也就没向这方面考虑过。但是现在的项目要求要有这项功能,并且在网上一搜会有很多,都挺好的,并且大致思想都差不多,所以我也研究了一下,自己实现了一个,并且把自己的实现实例记录了下来。希望能对需要的小伙伴提供帮助。
效果图:
实现字母索引导航条:
从界面上就可以看出要实现的主要功能为两部分:
第一,绘制字母,因为android 没有提供对应的组件所以只能通过自定view去绘制26英文字母和#号,这里就应该想到自定控件的三个常用方法,onMeasure ,onLayout,onDraw ,现在我要实现的就是一个绘制工作,并且没有子view ,所以onMeasure 和onLayout 就不需要重写。只需要实现onDraw就行啦,因为绘制的是文字 索引就应该使用到drawText ,同时还要计算出26个字母和#的平均高度,这样才能均匀分布。
第二就是实现对应字母的触摸事件,onTouchEvent方法,由当前触碰的位置获取到当前位子上的字母。
代码实现:
public class SideBar extends View {
private String initials[] = {"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","#"};
private Paint mPaint;
private int initialHeight;
private int touchItem = -1;
private SideBarItemSelectedListener listener;
public SideBar(Context context) {
this(context, null);
}
public SideBar(Context context, @Nullable AttributeSet attrs) {
this(context, attrs, 0);
}
public SideBar(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
initView();
}
private void initView() {
mPaint = new Paint();
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
int height = getHeight();//获取控件高度
int width = getWidth();//获取控件宽度
initialHeight = height / initials.length;//计算出要分陪给每个字母的高度
//进行绘制
for (int i = 0; i < initials.length; i++) {
mPaint.setColor(i == touchItem ? Color.GREEN : Color.BLUE);//如果当前字母被选中字体颜色就为绿色
mPaint.setAntiAlias(true);
mPaint.setTextSize(30);
float pionx = (width / 2 - mPaint.measureText(initials[i]) / 2);//字体的x轴上的位置
canvas.drawText(initials[i], pionx, (initialHeight * i) + initialHeight, mPaint);
mPaint.reset();
}
}
@Override
public boolean onTouchEvent(MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_MOVE:
case MotionEvent.ACTION_DOWN:
float point = event.getY();
int index = (int) (point / getHeight() * initials.length);// 通过获取触摸的y轴的位置,计算出是第几个字母
if (listener != null) {
touchItem = index;
listener.itemSelected(initials[index]);
}
return true;
case MotionEvent.ACTION_UP:
break;
}
invalidate();
return super.onTouchEvent(event);
}
public void setItemSelectedListener(SideBarItemSelectedListener listener) {
this.listener = listener;
}
public interface SideBarItemSelectedListener {//触摸事件的监听接口
void itemSelected(String str);
}
}
首字母索引还要解决一个问题,就是把汉字转换为拼音,看到网上有两种方法,一种是利用汉语转拼音的框架,另外一种就是通过汉字的ASCII码,我用的是网上的ASCII方法。
public class CharacterParser {
private static int[] pyvalue = new int[] { -20319, -20317, -20304, -20295,
-20292, -20283, -20265, -20257, -20242, -20230, -20051, -20036,
-20032, -20026, -20002, -19990, -19986, -19982, -19976, -19805,
-19784, -19775, -19774, -19763, -19756, -19751, -19746, -19741,
-19739, -19728, -19725, -19715, -19540, -19531, -19525, -19515,
-19500, -19484, -19479, -19467, -19289, -19288, -19281, -19275,
-19270, -19263, -19261, -19249, -19243, -19242, -19238, -19235,
-19227, -19224, -19218, -19212, -19038, -19023, -19018, -19006,
-19003, -18996, -18977, -18961, -18952, -18783, -18774, -18773,
-18763, -18756, -18741, -18735, -18731, -18722, -18710, -18697,
-18696, -18526, -18518, -18501, -18490, -18478, -18463, -18448,
-18447, -18446, -18239, -18237, -18231, -18220, -18211, -18201,
-18184, -18183, -18181, -18012, -17997, -17988, -17970, -17964,
-17961, -17950, -17947, -17931, -17928, -17922, -17759, -17752,
-17733, -17730, -17721, -17703, -17701, -17697, -17692, -17683,
-17676, -17496, -17487, -17482, -17468, -17454, -17433, -17427,
-17417, -17202, -17185, -16983, -16970, -16942, -16915, -16733,
-16708, -16706, -16689, -16664, -16657, -16647, -16474, -16470,
-16465, -16459, -16452, -16448, -16433, -16429, -16427, -16423,
-16419, -16412, -16407, -16403, -16401, -16393, -16220, -16216,
-16212, -16205, -16202, -16187, -16180, -16171, -16169, -16158,
-16155, -15959, -15958, -15944, -15933, -15920, -15915, -15903,
-15889, -15878, -15707, -15701, -15681, -15667, -15661, -15659,
-15652, -15640, -15631, -15625, -15454, -15448, -15436, -15435,
-15419, -15416, -15408, -15394, -15385, -15377, -15375, -15369,
-15363, -15362, -15183, -15180, -15165, -15158, -15153, -15150,
-15149, -15144, -15143, -15141, -15140, -15139, -15128, -15121,
-15119, -15117, -15110, -15109, -14941, -14937, -14933, -14930,
-14929, -14928, -14926, -14922, -14921, -14914, -14908, -14902,
-14894, -14889, -14882, -14873, -14871, -14857, -14678, -14674,
-14670, -14668, -14663, -14654, -14645, -14630, -14594, -14429,
-14407, -14399, -14384, -14379, -14368, -14355, -14353, -14345,
-14170, -14159, -14151, -14149, -14145, -14140, -14137, -14135,
-14125, -14123, -14122, -14112, -14109, -14099, -14097, -14094,
-14092, -14090, -14087, -14083, -13917, -13914, -13910, -13907,
-13906, -13905, -13896, -13894, -13878, -13870, -13859, -13847,
-13831, -13658, -13611, -13601, -13406, -13404, -13400, -13398,
-13395, -13391, -13387, -13383, -13367, -13359, -13356, -13343,
-13340, -13329, -13326, -13318, -13147, -13138, -13120, -13107,
-13096, -13095, -13091, -13076, -13068, -13063, -13060, -12888,
-12875, -12871, -12860, -12858, -12852, -12849, -12838, -12831,
-12829, -12812, -12802, -12607, -12597, -12594, -12585, -12556,
-12359, -12346, -12320, -12300, -12120, -12099, -12089, -12074,
-12067, -12058, -12039, -11867, -11861, -11847, -11831, -11798,
-11781, -11604, -11589, -11536, -11358, -11340, -11339, -11324,
-11303, -11097, -11077, -11067, -11055, -11052, -11045, -11041,
-11038, -11024, -11020, -11019, -11018, -11014, -10838, -10832,
-10815, -10800, -10790, -10780, -10764, -10587, -10544, -10533,
-10519, -10331, -10329, -10328, -10322, -10315, -10309, -10307,
-10296, -10281, -10274, -10270, -10262, -10260, -10256, -10254
};
public static String[] pystr = new String[] { "a", "ai", "an", "ang", "ao",
"ba", "bai", "ban", "bang", "bao", "bei", "ben", "beng", "bi",
"bian", "biao", "bie", "bin", "bing", "bo", "bu", "ca", "cai",
"can", "cang", "cao", "ce", "ceng", "cha", "chai", "chan", "chang",
"chao", "che", "chen", "cheng", "chi", "chong", "chou", "chu",
"chuai", "chuan", "chuang", "chui", "chun", "chuo", "ci", "cong",
"cou", "cu", "cuan", "cui", "cun", "cuo", "da", "dai", "dan",
"dang", "dao", "de", "deng", "di", "dian", "diao", "die", "ding",
"diu", "dong", "dou", "du", "duan", "dui", "dun", "duo", "e", "en",
"er", "fa", "fan", "fang", "fei", "fen", "feng", "fo", "fou", "fu",
"ga", "gai", "gan", "gang", "gao", "ge", "gei", "gen", "geng",
"gong", "gou", "gu", "gua", "guai", "guan", "guang", "gui", "gun",
"guo", "ha", "hai", "han", "hang", "hao", "he", "hei", "hen",
"heng", "hong", "hou", "hu", "hua", "huai", "huan", "huang", "hui",
"hun", "huo", "ji", "jia", "jian", "jiang", "jiao", "jie", "jin",
"jing", "jiong", "jiu", "ju", "juan", "jue", "jun", "ka", "kai",
"kan", "kang", "kao", "ke", "ken", "keng", "kong", "kou", "ku",
"kua", "kuai", "kuan", "kuang", "kui", "kun", "kuo", "la", "lai",
"lan", "lang", "lao", "le", "lei", "leng", "li", "lia", "lian",
"liang", "liao", "lie", "lin", "ling", "liu", "long", "lou", "lu",
"lv", "luan", "lue", "lun", "luo", "ma", "mai", "man", "mang",
"mao", "me", "mei", "men", "meng", "mi", "mian", "miao", "mie",
"min", "ming", "miu", "mo", "mou", "mu", "na", "nai", "nan",
"nang", "nao", "ne", "nei", "nen", "neng", "ni", "nian", "niang",
"niao", "nie", "nin", "ning", "niu", "nong", "nu", "nv", "nuan",
"nue", "nuo", "o", "ou", "pa", "pai", "pan", "pang", "pao", "pei",
"pen", "peng", "pi", "pian", "piao", "pie", "pin", "ping", "po",
"pu", "qi", "qia", "qian", "qiang", "qiao", "qie", "qin", "qing",
"qiong", "qiu", "qu", "quan", "que", "qun", "ran", "rang", "rao",
"re", "ren", "reng", "ri", "rong", "rou", "ru", "ruan", "rui",
"run", "ruo", "sa", "sai", "san", "sang", "sao", "se", "sen",
"seng", "sha", "shai", "shan", "shang", "shao", "she", "shen",
"sheng", "shi", "shou", "shu", "shua", "shuai", "shuan", "shuang",
"shui", "shun", "shuo", "si", "song", "sou", "su", "suan", "sui",
"sun", "suo", "ta", "tai", "tan", "tang", "tao", "te", "teng",
"ti", "tian", "tiao", "tie", "ting", "tong", "tou", "tu", "tuan",
"tui", "tun", "tuo", "wa", "wai", "wan", "wang", "wei", "wen",
"weng", "wo", "wu", "xi", "xia", "xian", "xiang", "xiao", "xie",
"xin", "xing", "xiong", "xiu", "xu", "xuan", "xue", "xun", "ya",
"yan", "yang", "yao", "ye", "yi", "yin", "ying", "yo", "yong",
"you", "yu", "yuan", "yue", "yun", "za", "zai", "zan", "zang",
"zao", "ze", "zei", "zen", "zeng", "zha", "zhai", "zhan", "zhang",
"zhao", "zhe", "zhen", "zheng", "zhi", "zhong", "zhou", "zhu",
"zhua", "zhuai", "zhuan", "zhuang", "zhui", "zhun", "zhuo", "zi",
"zong", "zou", "zu", "zuan", "zui", "zun", "zuo"
};
private StringBuilder buffer;
private String resource;
private static CharacterParser characterParser = new CharacterParser();
public static CharacterParser getInstance() {
return characterParser;
}
public String getResource() {
return resource;
}
public void setResource(String resource) {
this.resource = resource;
}
/** * 汉字转成ASCII码 * * @param chs * @return */
private int getChsAscii(String chs) {
int asc = 0;
try {
byte[] bytes = chs.getBytes("gb2312");
if (bytes == null || bytes.length > 2 || bytes.length <= 0) {
throw new RuntimeException("illegal resource string");
}
if (bytes.length == 1) {
asc = bytes[0];
}
if (bytes.length == 2) {
int hightByte = 256 + bytes[0];
int lowByte = 256 + bytes[1];
asc = (256 * hightByte + lowByte) - 256 * 256;
}
} catch (Exception e) {
System.out
.println("ERROR:ChineseSpelling.class-getChsAscii(String chs)"
+ e);
}
return asc;
}
/** * 单字解析 * * @param str * @return */
public String convert(String str) {
String result = null;
int ascii = getChsAscii(str);
if (ascii > 0 && ascii < 160) {
result = String.valueOf((char) ascii);
} else {
for (int i = (pyvalue.length - 1); i >= 0; i--) {
if (pyvalue[i] <= ascii) {
result = pystr[i];
break;
}
}
}
return result;
}
/** * 词组解析 * * @param chs * @return */
public String getSelling(String chs) {
if (chs == null) {
return null;
}
String key, value;
buffer = new StringBuilder();
for (int i = 0; i < chs.length(); i++) {
key = chs.substring(i, i + 1);
if (key.getBytes().length >= 2) {
value = (String) convert(key);
if (value == null) {
value = "unknown";
}
} else {
value = key;
}
buffer.append(value);
}
return buffer.toString();
}
public String getSpelling() {
return this.getSelling(this.getResource());
}
}
测试demo
布局文件:我这里的列表控件使用的是RecyclerView ,其实不管是ListView 还是RecyclerView都一样看个人使用习惯。
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<android.support.v7.widget.RecyclerView
android:id="@+id/recycelview"
android:layout_width="match_parent"
android:layout_height="match_parent"
/>
<demo.song.com.sidebar.SideBar
android:id="@+id/sidebar"
android:layout_width="30dp"
android:layout_height="match_parent"
android:layout_gravity="center|right"
android:padding="10dp"
/>
</FrameLayout>
MainActivity 代码
public class MainActivity extends AppCompatActivity {
private final String TAG = MainActivity.class.getSimpleName();
private SideBar mSideBar;
private List<CityInfo> citys;
private RecyclerView mRecyclerView;
private CityAdapter mCityAdapter;
private static Toast makeText;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initData();
mSideBar = findViewById(R.id.sidebar);
mRecyclerView = findViewById(R.id.recycelview);
mSideBar.setItemSelectedListener(new SideBar.SideBarItemSelectedListener() {
@Override
public void itemSelected(String str) {
int index = mCityAdapter.getIndex(str);
showToast(str);
if (index != -1) {
mRecyclerView.scrollToPosition(index);
}
}
});
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);
linearLayoutManager.setOrientation(LinearLayoutManager.VERTICAL);
mRecyclerView.setLayoutManager(linearLayoutManager);
mCityAdapter = new CityAdapter();
mRecyclerView.addItemDecoration(new DividerItemDecoration(this, DividerItemDecoration.VERTICAL));
mRecyclerView.setAdapter(mCityAdapter);
}
private void showToast(String str) {
if (makeText == null) {
makeText = Toast.makeText(MainActivity.this, str, Toast.LENGTH_SHORT);
makeText.setGravity(Gravity.CENTER, 0, 0);
} else {
makeText.setText(str);
makeText.setDuration(Toast.LENGTH_SHORT);
}
makeText.show();
}
private void initData() {
citys = new ArrayList<>();
citys.add(new CityInfo("北京", 1));
citys.add(new CityInfo("上海", 2));
citys.add(new CityInfo("天津", 3));
citys.add(new CityInfo("重庆", 4));
citys.add(new CityInfo("山东", 5));
citys.add(new CityInfo("山西", 6));
citys.add(new CityInfo("河南", 7));
citys.add(new CityInfo("河北", 8));
citys.add(new CityInfo("广东", 9));
citys.add(new CityInfo("广西", 10));
citys.add(new CityInfo("安徽", 11));
citys.add(new CityInfo("江苏", 12));
citys.add(new CityInfo("福建", 13));
citys.add(new CityInfo("湖南", 14));
citys.add(new CityInfo("湖北", 15));
citys.add(new CityInfo("浙江", 16));
citys.add(new CityInfo("四川", 17));
citys.add(new CityInfo("云南", 18));
citys.add(new CityInfo("台湾", 19));
citys.add(new CityInfo("辽宁", 20));
citys.add(new CityInfo("吉林", 21));
citys.add(new CityInfo("黑龙江", 22));
citys.add(new CityInfo("西藏", 23));
citys.add(new CityInfo("青海", 24));
citys.add(new CityInfo("新疆", 25));
citys.add(new CityInfo("宁夏", 26));
citys.add(new CityInfo("#东京", 27));
citys.add(new CityInfo("@伦敦", 28));
for (CityInfo city : citys) {
String pinyin = CharacterParser.getInstance().getSelling(city.getName());
String letter = pinyin.substring(0, 1);
if (letter.matches("\\w")) {// 匹配拼音第一个位置是否为a-zA-Z
city.setLetter(letter.toUpperCase());
} else {
city.setLetter("#");
}
}
Collections.sort(citys, new PinyinComparable());
}
public class PinyinComparable implements Comparator<CityInfo> {
@Override
public int compare(CityInfo cityInfo, CityInfo t1) {
if (cityInfo.getLetter().equals("@") || t1.getLetter().equals("#")) {
return -1;
} else if (cityInfo.getLetter().equals("#") || t1.getLetter().equals("@")) {
return 1;
}
return cityInfo.getLetter().compareTo(t1.getLetter());
}
}
private class CityAdapter extends RecyclerView.Adapter<CityHolder> {
@NonNull
@Override
public CityHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
View view = android.view.LayoutInflater.from(MainActivity.this).inflate(R.layout.layout_item, viewGroup, false);
CityHolder holder = new CityHolder(view);
return holder;
}
@Override
public void onBindViewHolder(@NonNull CityHolder cityHolder, int i) {
cityHolder.cityname.setText(citys.get(i).getName());
}
@Override
public int getItemCount() {
return citys.size();
}
public int getIndex(String letter) {
for (CityInfo cityInfo : citys) {
if (cityInfo.getLetter().equals(letter)) {
return citys.indexOf(cityInfo);
}
}
return -1;
}
}
private class CityHolder extends RecyclerView.ViewHolder {
private android.widget.TextView cityname;
public CityHolder(@NonNull View itemView) {
super(itemView);
cityname = itemView.findViewById(R.id.tv_city);
}
}
}
到这里一个完整的首字母索引的demo 已经完成了,里面没有复杂的逻辑,应该是android自定view比较简单的了。如果有需要优化和改进的地方,希望大家指正,源码地址 https://github.com/songdaren123/SideBar