Android实现仿通讯录侧边栏滑动SiderBar效果代码

package com.freesonfish.listview_index; 
import android.content.Context; 
import android.graphics.Canvas; 
import android.graphics.Color; 
import android.graphics.Paint; 
import android.util.AttributeSet; 
import android.view.MotionEvent; 
import android.view.View; 
public class MySideBar extends View { 
  private OnTouchingLetterChangedListener touchListener; 
  // 26个字母 
  public static String[] b = { "#", "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 boolean showBkg = false; 
  int choose = -1; 
  int scrollChoose = -1; 
  Paint paint = new Paint(); 
  Paint rectPaint = new Paint(); 
  float rectWidth = 0f; 
  public MySideBar(Context context, AttributeSet attrs, int defStyle) { 
    super(context, attrs, defStyle); 
    init(); 
  } 
  public MySideBar(Context context, AttributeSet attrs) { 
    super(context, attrs); 
    init(); 
  } 
  public MySideBar(Context context) { 
    super(context); 
    init(); 
  } 
  private void init() { 
    rectPaint.setColor(Color.parseColor("#CCCCCC")); 
    rectWidth = paint.measureText("#"); 
  } 
  /** 
   * 重写这个方法 
   */ 
  protected void onDraw(Canvas canvas) { 
    super.onDraw(canvas); 
    if (showBkg) { 
      canvas.drawColor(Color.parseColor("#CCCCCC")); 
    } 
    final int height = getHeight(); 
    final int width = getWidth(); 
    final int singleHeight = height / b.length; 
    final float xRectPos = ((float) width - paint.measureText("#")) / 2.0f - rectWidth; 
    final float xRectPos2 = xRectPos + 3.0f * rectWidth; 
    for (int i = 0; i < b.length; i++) { 
      paint.setFakeBoldText(true); 
      paint.setAntiAlias(true); 
      final float xPos = ((float) width - paint.measureText(b[i])) / 2.0f;
      final float yPos = singleHeight * i + singleHeight; 
      if (i == choose) { 
        paint.setColor(Color.RED); 
        canvas.drawRect(xRectPos, yPos - singleHeight / 2.0f, xRectPos2, yPos + rectWidth, rectPaint); 
      } 
      canvas.drawText(b[i], xPos, yPos, paint); 
      paint.reset(); 
    } 
  } 
  @Override 
  public boolean dispatchTouchEvent(MotionEvent event) { 
    final int action = event.getAction(); 
    final float y = event.getY(); 
    final int c = (int) (y / getHeight() * b.length); 
    switch (action) { 
    case MotionEvent.ACTION_DOWN: 
      showBkg = true; 
      if (choose != c && touchListener != null) { 
        doOnActionDown(c); 
      } 
      break; 
    case MotionEvent.ACTION_MOVE: 
      if (choose != c && touchListener != null) { 
        doOnActionDown(c); 
      } 
      break; 
    case MotionEvent.ACTION_UP: 
      showBkg = false; 
      invalidate(); 
      break; 
    } 
    return true; 
  } 
  /** 
   * listview滚动时候调用它 
   * 
   * @param c 
   */ 
  public void setColorWhenListViewScrolling(int c) { 
    if (scrollChoose != c) { 
      scrollChoose = c; 
      String string = ListContantsUtil.AbcList.get(c); 
      for (int i = c; i < b.length; ++i) { 
        if (string.equals(b[i])) { 
          choose = i; 
          invalidate(); 
          break; 
        } 
      } 
    } 
  } 
  /** 
   * 当侧边栏被按下的动作 
   * @param c 
   */ 
  private void doOnActionDown(int c) { 
    if (c > 0 && c < b.length) { 
      if (ListContantsUtil.indexPositionMap.containsKey(b[c])) { 
        touchListener.onTouchingLetterChanged(b[c]); 
        choose = c; 
        invalidate(); 
      } else { 
        c = c - 1; 
        doOnActionDown(c); 
      } 
    } 
  } 
  @Override 
  public boolean onTouchEvent(MotionEvent event) { 
    return super.onTouchEvent(event); 
  } 
  public void setOnTouchingLetterChangedListener(OnTouchingLetterChangedListener touchListener) { 
    this.touchListener = touchListener; 
  } 
  /** 
   * 用来通知activity显示选中的字母 
   * @author freeson 
   * 
   */ 
  public interface OnTouchingLetterChangedListener { 
    public void onTouchingLetterChanged(String s); 
  } 
}

package com.freesonfish.listview_index; 
import java.util.ArrayList; 
import java.util.HashMap; 
import java.util.List; 
public class ListContantsUtil { 
  static final List<Integer> indexPositionList = new ArrayList<Integer>(); 
  static final List<String> AbcList = new ArrayList<String>(); 
  static final HashMap<String, Integer> indexPositionMap = new HashMap<String, Integer>(); 
  static void putNameIndexToMap(List<String> list, HashMap<String, String> nameAndPinyin) { 
    int lenght = list.size(); 
    for (int i = 0; i < lenght; ++i) { 
      String name = nameAndPinyin.get(list.get(i)).substring(0, 1); 
      // 判断该字符是属于字母还是数字或其他的 
      int ascii = name.toCharArray()[0]; 
      if (ascii >= 65 && ascii <= 90) { 
        if (!indexPositionMap.containsKey(name)) { 
          indexPositionMap.put(name, i); 
          AbcList.add(name); 
          indexPositionList.add(i); 
        } 
      } else { 
        if (!indexPositionMap.containsKey("#")) { 
          indexPositionMap.put("#", i); 
          AbcList.add("#"); 
          indexPositionList.add(i); 
        } 
      } 
    } 
  } 
}