冲刺十四天（实现好友页的排序展示）

实现好友页的字母排序展示

　　采用的一个汉字转汉语拼音的第三方库

implementation 'com.belerweb:pinyin4j:2.5.1'//转拼音

　　自定义一个sidebar布局文件来展示拼音

package com.example.newbsh.UI.friends.list;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.widget.TextView;

import com.example.newbsh.R;

public class SideBar extends androidx.appcompat.widget.AppCompatTextView {
    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", "#"};
    private Paint textPaint;
    private Paint bigTextPaint;
    private Paint scaleTextPaint;

    private Canvas canvas;
    private int itemH;
    private int w;
    private int h;
    /**
     * 普通情况下字体大小
     */
    float singleTextH;
    /**
     * 缩放离原始的宽度
     */
    private float scaleWidth;
    /**
     * 滑动的Y
     */
    private float eventY = 0;
    /**
     * 缩放的倍数
     */
    private int scaleSize = 1;
    /**
     * 缩放个数item，即开口大小
     */
    private int scaleItemCount = 6;
    private ISideBarSelectCallBack callBack;

    public SideBar(Context context) {
        this(context, null);
    }

    public SideBar(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public SideBar(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init(attrs);
    }

    private void init(AttributeSet attrs) {
        if (attrs != null) {
            TypedArray ta = getContext().obtainStyledAttributes(attrs, R.styleable.SideBar);
            scaleSize = ta.getInteger(R.styleable.SideBar_scaleSize, 1);
            scaleItemCount = ta.getInteger(R.styleable.SideBar_scaleItemCount, 6);
            scaleWidth = ta.getDimensionPixelSize(R.styleable.SideBar_scaleWidth, dp(100));
            ta.recycle();
        }
        textPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        textPaint.setColor(getCurrentTextColor());
        textPaint.setTextSize(getTextSize());
        textPaint.setTextAlign(Paint.Align.CENTER);
        bigTextPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        bigTextPaint.setColor(getCurrentTextColor());
        bigTextPaint.setTextSize(getTextSize() * (scaleSize + 3));
        bigTextPaint.setTextAlign(Paint.Align.CENTER);
        scaleTextPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        scaleTextPaint.setColor(getCurrentTextColor());
        scaleTextPaint.setTextSize(getTextSize() * (scaleSize + 1));
        scaleTextPaint.setTextAlign(Paint.Align.CENTER);
    }

    public void setDataResource(String[] data) {
        letters = data;
        invalidate();
    }

    public void setOnStrSelectCallBack(ISideBarSelectCallBack callBack) {
        this.callBack = callBack;
    }

    /**
     * 设置字体缩放比例
     *
     * @param scale
     */
    public void setScaleSize(int scale) {
        scaleSize = scale;
        invalidate();
    }

    /**
     * 设置缩放字体的个数，即开口大小
     *
     * @param scaleItemCount
     */
    public void setScaleItemCount(int scaleItemCount) {
        this.scaleItemCount = scaleItemCount;
        invalidate();
    }

    private int dp(int px) {
        final float scale = getContext().getResources().getDisplayMetrics().density;
        return (int) (px * scale + 0.5f);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
            case MotionEvent.ACTION_MOVE:
                if (event.getX() > (w - getPaddingRight() - singleTextH - 10)) {
                    eventY = event.getY();
                    invalidate();
                    return true;
                } else {
                    eventY = 0;
                    invalidate();
                    break;
                }
            case MotionEvent.ACTION_CANCEL:
                eventY = 0;
                invalidate();
                return true;
            case MotionEvent.ACTION_UP:
                if (event.getX() > (w - getPaddingRight() - singleTextH - 10)) {
                    eventY = 0;
                    invalidate();
                    return true;
                } else
                    break;
        }
        return super.onTouchEvent(event);
    }


    @Override
    protected void onDraw(Canvas canvas) {
        this.canvas = canvas;
        DrawView(eventY);
    }

    private void DrawView(float y) {
        int currentSelectIndex = -1;
        if (y != 0) {
            for (int i = 0; i < letters.length; i++) {
                float currentItemY = itemH * i;
                float nextItemY = itemH * (i + 1);
                if (y >= currentItemY && y < nextItemY) {
                    currentSelectIndex = i;
                    if (callBack != null) {
                        callBack.onSelectStr(currentSelectIndex, letters[i]);
                    }
                    //画大的字母
                    Paint.FontMetrics fontMetrics = bigTextPaint.getFontMetrics();
                    float bigTextSize = fontMetrics.descent - fontMetrics.ascent;
                    canvas.drawText(letters[i], w - getPaddingRight() - scaleWidth - bigTextSize, singleTextH + itemH * i, bigTextPaint);
                }
            }
        }
        drawLetters(y, currentSelectIndex);
    }

    private void drawLetters(float y, int index) {
        //第一次进来没有缩放情况，默认画原图
        if (index == -1) {
            w = getMeasuredWidth();
            h = getMeasuredHeight();
            itemH = h / letters.length;
            Paint.FontMetrics fontMetrics = textPaint.getFontMetrics();
            singleTextH = fontMetrics.descent - fontMetrics.ascent;
            for (int i = 0; i < letters.length; i++) {
                canvas.drawText(letters[i], w - getPaddingRight(), singleTextH + itemH * i, textPaint);
            }
            //触摸的时候画缩放图
        } else {
            //遍历所有字母
            for (int i = 0; i < letters.length; i++) {
                //要画的字母的起始Y坐标
                float currentItemToDrawY = singleTextH + itemH * i;
                float centerItemToDrawY;
                if (index < i)
                    centerItemToDrawY = singleTextH + itemH * (index + scaleItemCount);
                else
                    centerItemToDrawY = singleTextH + itemH * (index - scaleItemCount);
                float delta = 1 - Math.abs((y - currentItemToDrawY) / (centerItemToDrawY - currentItemToDrawY));
                float maxRightX = w - getPaddingRight();
                //如果大于0，表明在y坐标上方
                scaleTextPaint.setTextSize(getTextSize() + getTextSize() * delta);
                float drawX = maxRightX - scaleWidth * delta;
                //超出边界直接花在边界上
                if (drawX > maxRightX)
                    canvas.drawText(letters[i], maxRightX, singleTextH + itemH * i, textPaint);
                else
                    canvas.drawText(letters[i], drawX, singleTextH + itemH * i, scaleTextPaint);
            }
        }
    }

    public interface ISideBarSelectCallBack {
        void onSelectStr(int index, String selectStr);
    }

}

　　创建汉字转换位汉语拼音，英文字符不变的一个工具类

package com.example.newbsh.UI.friends.list;

import net.sourceforge.pinyin4j.PinyinHelper;
import net.sourceforge.pinyin4j.format.HanyuPinyinCaseType;
import net.sourceforge.pinyin4j.format.HanyuPinyinOutputFormat;
import net.sourceforge.pinyin4j.format.HanyuPinyinToneType;

/**
 * 汉字转换位汉语拼音，英文字符不变
 */
public class Cn2Spell {

    public static StringBuffer sb = new StringBuffer();

    /**
     * 获取汉字字符串的首字母，英文字符不变
     * 例如：阿飞→af
     */
    public static String getPinYinHeadChar(String chines) {
        sb.setLength(0);
        char[] chars = chines.toCharArray();
        HanyuPinyinOutputFormat defaultFormat = new HanyuPinyinOutputFormat();
        defaultFormat.setCaseType(HanyuPinyinCaseType.LOWERCASE);
        defaultFormat.setToneType(HanyuPinyinToneType.WITHOUT_TONE);
        for (int i = 0; i < chars.length; i++) {
            if (chars[i] > 128) {
                try {
                    sb.append(PinyinHelper.toHanyuPinyinStringArray(chars[i], defaultFormat)[0].charAt(0));
                } catch (Exception e) {
                    e.printStackTrace();
                }
            } else {
                sb.append(chars[i]);
            }
        }
        return sb.toString();
    }

    /**
     * 获取汉字字符串的第一个字母
     */
    public static String getPinYinFirstLetter(String str) {
        sb.setLength(0);
        char c = str.charAt(0);
        String[] pinyinArray = PinyinHelper.toHanyuPinyinStringArray(c);
        if (pinyinArray != null) {
            sb.append(pinyinArray[0].charAt(0));
        } else {
            sb.append(c);
        }
        return sb.toString();
    }

    /**
     * 获取汉字字符串的汉语拼音，英文字符不变
     */
    public static String getPinYin(String chines) {
        sb.setLength(0);
        char[] nameChar = chines.toCharArray();
        HanyuPinyinOutputFormat defaultFormat = new HanyuPinyinOutputFormat();
        defaultFormat.setCaseType(HanyuPinyinCaseType.LOWERCASE);
        defaultFormat.setToneType(HanyuPinyinToneType.WITHOUT_TONE);
        for (int i = 0; i < nameChar.length; i++) {
            if (nameChar[i] > 128) {
                try {
                    sb.append(PinyinHelper.toHanyuPinyinStringArray(nameChar[i], defaultFormat)[0]);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            } else {
                sb.append(nameChar[i]);
            }
        }
        return sb.toString();
    }

}

　　一个排序的adapter，来展示好友列表

package com.example.newbsh.UI.friends.list;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;
import android.widget.Toast;

import com.example.newbsh.R;

import java.util.List;

public class SortAdapter extends BaseAdapter {

    private List<User> list = null;
    private Context mContext;

    public SortAdapter(Context mContext, List<User> list) {
        this.mContext = mContext;
        this.list = list;
    }

    public int getCount() {
        return this.list.size();
    }

    public Object getItem(int position) {
        return list.get(position);
    }

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

    public View getView(final int position, View view, ViewGroup arg2) {
        ViewHolder viewHolder;
        final User user = list.get(position);
        if (view == null) {
            viewHolder = new ViewHolder();
            view = LayoutInflater.from(mContext).inflate(R.layout.friend_item, null);
            viewHolder.name = (TextView) view.findViewById(R.id.name);
            viewHolder.catalog = (TextView) view.findViewById(R.id.catalog);
            view.setTag(viewHolder);
        } else {
            viewHolder = (ViewHolder) view.getTag();
        }

        //根据position获取首字母作为目录catalog
        String catalog = list.get(position).getFirstLetter();

        //如果当前位置等于该分类首字母的Char的位置 ，则认为是第一次出现
        if(position == getPositionForSection(catalog)){
            viewHolder.catalog.setVisibility(View.VISIBLE);
            viewHolder.catalog.setText(user.getFirstLetter().toUpperCase());
        }else{
            viewHolder.catalog.setVisibility(View.GONE);
        }

        viewHolder.name.setText(this.list.get(position).getName());
        return view;

    }

    final static class ViewHolder {
        TextView catalog;
        TextView name;
    }

    /**
     * 获取catalog首次出现位置
     */
    public int getPositionForSection(String catalog) {
        for (int i = 0; i < getCount(); i++) {
            String sortStr = list.get(i).getFirstLetter();
            if (catalog.equalsIgnoreCase(sortStr)) {
                return i;
            }
        }
        return -1;
    }

}

　　　FriendFragment的设置，装配好友信息（没有写添加好友，目前是静态数据）

package com.example.newbsh.UI.friends;

import androidx.lifecycle.ViewModelProviders;

import android.os.Bundle;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;

import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ListView;
import android.widget.TextView;

import com.example.newbsh.MainActivity;
import com.example.newbsh.R;
import com.example.newbsh.UI.friends.list.SideBar;
import com.example.newbsh.UI.friends.list.SortAdapter;
import com.example.newbsh.UI.friends.list.User;

import java.util.ArrayList;
import java.util.Collections;

public class FriendFragment extends Fragment {

    private FriendViewModel mViewModel;
    private View view;
    private ListView listView;
    private SideBar sideBar;
    private ArrayList<User> list;
    private String getUsername(){
        return MainActivity.getUserName();
    }
    public static FriendFragment newInstance() {
        return new FriendFragment();
    }
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container,
                             @Nullable Bundle savedInstanceState) {
        view=inflater.inflate(R.layout.friend_fragment, container, false);
        return view;
    }

    @Override
    public void onActivityCreated(@Nullable Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        mViewModel = ViewModelProviders.of(this).get(FriendViewModel.class);
        // TODO: Use the ViewModel
        initView();
        initData();
    }
    private void initView() {
        listView = (ListView) view.findViewById(R.id.listView);
        sideBar = (SideBar) view.findViewById(R.id.side_bar);
        sideBar.setOnStrSelectCallBack(new SideBar.ISideBarSelectCallBack() {
            @Override
            public void onSelectStr(int index, String selectStr) {
                for (int i = 0; i < list.size(); i++) {
                    if (selectStr.equalsIgnoreCase(list.get(i).getFirstLetter())) {
                        listView.setSelection(i); // 选择到首字母出现的位置
                        return;
                    }
                }
            }
        });
    }

    private void initData() {
        list = new ArrayList<>();
        list.add(new User("亳州")); // 亳[bó]属于不常见的二级汉字
        list.add(new User("大娃"));
        list.add(new User("二娃"));
        list.add(new User("三娃"));
        list.add(new User("四娃"));
        list.add(new User("五娃"));
        list.add(new User("六娃"));
        list.add(new User("七娃"));
        list.add(new User("喜羊羊"));
        list.add(new User("美羊羊"));
        list.add(new User("懒羊羊"));
        list.add(new User("沸羊羊"));
        list.add(new User("暖羊羊"));
        list.add(new User("慢羊羊"));
        list.add(new User("灰太狼"));
        list.add(new User("红太狼"));
        list.add(new User("孙悟空"));
        list.add(new User("黑猫警长"));
        list.add(new User("舒克"));
        list.add(new User("贝塔"));
        list.add(new User("海尔"));
        list.add(new User("阿凡提"));
        list.add(new User("邋遢大王"));
        list.add(new User("哪吒"));
        list.add(new User("没头脑"));
        list.add(new User("不高兴"));
        list.add(new User("蓝皮鼠"));
        list.add(new User("大脸猫"));
        list.add(new User("大头儿子"));
        list.add(new User("小头爸爸"));
        list.add(new User("蓝猫"));
        list.add(new User("淘气"));
        list.add(new User("叶峰"));
        list.add(new User("楚天歌"));
        list.add(new User("江流儿"));
        list.add(new User("Tom"));
        list.add(new User("Jerry"));
        list.add(new User("12345"));
        list.add(new User("54321"));
        list.add(new User("_(:з」∠)_"));
        list.add(new User("……%￥#￥%#"));
        Collections.sort(list); // 对list进行排序，需要让User实现Comparable接口重写compareTo方法
        SortAdapter adapter = new SortAdapter(view.getContext(), list);
        listView.setAdapter(adapter);
    }
}

　　最终展示

 点击右侧会有大波浪来展示当前的字母排序的好友