快速索引

如下是快速索引的效果图，是从网上下的实例。如图实现的难点1:是最右侧的索引是用自定义View来实现的，主要通过onDraw的方法将其画出；

难点2:是如何拿到每个名字的首字母用的是pinyin4j-2.5.0.jar  将汉字转化成拼音再去第一个字符；难点3:ListView的adapte不好实现

下图的布局是一个ListView右侧是一个自定义的View，中间是一个TextView点击的时候显示

如下是自定义的View来实现快速索引

 1 package com.demo.sb.widget; 2  3 import android.content.Context; 4 import android.graphics.Canvas; 5 import android.graphics.Color; 6 import android.graphics.Paint; 7 import android.graphics.Rect; 8 import android.graphics.Typeface; 9 import android.util.AttributeSet; 10 import android.util.Log; 11 import android.view.MotionEvent; 12 import android.view.View; 13  14 /** 15  * 快速索引 用于根据字母快速定位联系人 也就是界面最右边的那个红色竖条 16  *  17  * @author Administrator 18  *  19 */ 20 public class QuickIndexBar extends View { 21  22   private static final String[] LETTERS = new String[] { "A", "B", "C", "D", 23       "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", 24       "R", "S", "T", "U", "V", "W", "X", "Y", "Z" }; 25  26   private Paint mPaint; 27  28   private float cellHeight; 29  30   private int cellWidth; 31  32   /** 33    * 暴露一个字母的监听 34   */ 35   public interface OnLetterUpdateListener { 36     void onLetterUpdate(String letter); 37   } 38  39   private OnLetterUpdateListener listener; 40  41   public OnLetterUpdateListener getListener() { 42     return listener; 43   } 44  45   /** 46    * 设置字母更新的监听 47   */ 48   public void setListener(OnLetterUpdateListener listener) { 49     this.listener = listener; 50   } 51  52   public QuickIndexBar(Context context) { 53     this(context, null); 54     // TODO Auto-generated constructor stub 55   } 56  57   public QuickIndexBar(Context context, AttributeSet attrs) { 58     this(context, attrs, 0); 59     // TODO Auto-generated constructor stub 60   } 61  62   public QuickIndexBar(Context context, AttributeSet attrs, int defStyleAttr) { 63     super(context, attrs, defStyleAttr); 64     mPaint = new Paint(Paint.ANTI_ALIAS_FLAG); 65     mPaint.setColor(Color.WHITE); 66     mPaint.setTypeface(Typeface.DEFAULT_BOLD); 67   } 68  69   @Override 70   protected void onSizeChanged(int w, int h, int oldw, int oldh) { 71     // TODO Auto-generated method stub 72     super.onSizeChanged(w, h, oldw, oldh); 73     cellWidth = getMeasuredWidth(); 74  75     int mHeight = getMeasuredHeight(); 76     cellHeight = mHeight * 1.0f / LETTERS.length; 77   } 78  79   /** 80    * 绘制自定义最重要的一步重写onDraw方法 画什么，由Canvas处理 怎么画，由Paint处理 81   */ 82   @Override 83   protected void onDraw(Canvas canvas) { 84     // TODO Auto-generated method stub 85     for (int i = 0; i < LETTERS.length; i++) { 86       String text = LETTERS[i]; 87       // 计算坐标 88       int x = (int) (cellWidth / 2.0f - mPaint.measureText(text) / 2.0f); 89       // 获取文本的高度 90       Rect bounds = new Rect();// 矩形 91       mPaint.getTextBounds(text, 0, text.length(), bounds); 92       int textHeight = bounds.height(); 93       int y = (int) (cellHeight / 2.0f + textHeight / 2.0f + i 94           * cellHeight); 95  96       // 根据按下的字母，设置画笔颜色 97       mPaint.setColor(touchIndex == i ? Color.GRAY : Color.WHITE); 98  99       // 绘制文本A-Z100       canvas.drawText(text, x, y, mPaint);101     }102   }103 104   int touchIndex = -1;105 106   @Override107   public boolean onTouchEvent(MotionEvent event) {108     // TODO Auto-generated method stub109     int index = -1;110     switch (event.getAction()) {111     case MotionEvent.ACTION_DOWN:112       // 获取当前触摸到的字母索引113       index = (int) (event.getY() / cellHeight);114       if (index >= 0 && index < LETTERS.length) {115         // 判断是否跟上一次触摸到的一样116         if (index != touchIndex) {117 118           if (listener != null) {119             listener.onLetterUpdate(LETTERS[index]);120           }121 122           Log.d("jiejie", "onTouchEvent: " + LETTERS[index]);123 124           touchIndex = index;125         }126       }127       break;128     case MotionEvent.ACTION_MOVE:129 130       index = (int) (event.getY() / cellHeight);131       if (index >= 0 && index < LETTERS.length) {132         // 判断是否跟上一次触摸到的一样133         if (index != touchIndex) {134 135           if (listener != null) {136             listener.onLetterUpdate(LETTERS[index]);137           }138 139           Log.d("jiejie", "onTouchEvent : " + LETTERS[index]);140           touchIndex = index;141         }142       }143       break;144     case MotionEvent.ACTION_UP:145       touchIndex = -1;146       break;147     default:148       break;149     }150     // 重新绘制151     invalidate();152     return true;153   }154 }

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原标题：快速索引

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