字母索引实现方式主要是通过Adapter继承 SectionIndexer接口，如下

public class HeaderAdapter extends ArrayAdapter<String> implements SectionIndexer {

private List<String> items=new ArrayList<String>();
private LayoutInflater mInflater;
private int resource;
private int textViewResourceId;
private String[] sections;
private HashMap<String,Integer> maps=new HashMap<String, Integer>();

	public HeaderAdapter(Context context, int resource, int textViewResourceId,
			List<String> items) {
		
		super(context, resource, textViewResourceId, items);
		this.items=items;
		mInflater=LayoutInflater.from(context);
		this.resource=resource;
		this.textViewResourceId=textViewResourceId;
		//A-Z字母列表
		sections=context.getResources().getStringArray(R.array.sections);
		initMaps();
		// TODO Auto-generated constructor stub
	}
	private void initMaps(){

        //遍历数据源，用来保存相应字母的position位置

		for (int i=0;i<items.size();i++) {
			String start=items.get(i).substring(0,1).toUpperCase();
			if(!maps.containsKey(start)){
                          maps.put(start, i);
		       }
		}
	}
	
	
	@Override
	public int getCount() {
		// TODO Auto-generated method stub
		return items.size();
	}




	@Override
	public String getItem(int position) {
		// TODO Auto-generated method stub
		return items.get(position);
	}




	@Override
	public long getItemId(int position) {
		// TODO Auto-generated method stub
		return super.getItemId(position);
	}




	@Override
	public int getPosition(String item) {
		// TODO Auto-generated method stub
		return super.getPosition(item);
	}




	@Override
	public View getView(int position, View convertView, ViewGroup parent) {
		// TODO Auto-generated method stub
		convertView =mInflater.inflate(resource, null);
		TextView textView=(TextView)convertView.findViewById(textViewResourceId);
		TextView header=(TextView)convertView.findViewById(R.id.header);
		String text=items.get(position);
		String start=text.substring(0, 1).toUpperCase();
	    if(maps.containsKey(start)&&maps.containsValue(position)){
	    	header.setVisibility(View.VISIBLE);
	    	header.setText(start);	
	    }

		textView.setText(text);
		
		return convertView;
	}

	

	public int getPositionForSection(int sectionIndex) {
		// TODO Auto-generated method stub

//主要方法根据字母索引位置，获取需要滚动的position位置

       if(maps.get(sections[position])==null){
    	   return -1;
       }
		return maps.get(sections[sectionIndex]);
	}

	public int getSectionForPosition(int position) {
		// TODO Auto-generated method stub

		return 0;
	}

	public String[] getSections() {
		// TODO Auto-generated method stub
		
		return sections;
	}

}

2.自定义SearchBar，实现字母索引

public class SearchBar extends View {
    private String[] section;
    private int height;

    private int indexHeight;//
    private Paint textPaint;
    private int width;
    private int sectionLength;
    private int curSetion;
    private Rect mIndicatorRect = new Rect();
    private Drawable mIndicatorDrawable;
    private SectionIndexer mIndexer;
    private ListView mList;
    private PopupWindow mPopupWindow;
    private TextView mPromptText;
	public SearchBar(Context context) {
		this(context,null);
		// TODO Auto-generated constructor stub
	}
	public SearchBar(Context context,AttributeSet attr) {
		this(context,attr,0);
		// TODO Auto-generated constructor stub
	}
	public SearchBar(Context context,AttributeSet attr,int def) {
		super(context,attr,0);
		// TODO Auto-generated constructor stub

//A-Z

		section=getResources().getStringArray(R.array.sections);
	    sectionLength=section.length;
		textPaint=new Paint();
		textPaint.setColor(Color.BLACK);
		textPaint.setTextSize(14);
		mIndicatorDrawable = getResources().getDrawable(R.drawable.bladeview_indicator_normal);
		mPromptText=(TextView)LayoutInflater.from(context).inflate(R.layout.popup_text, null);
	}
	
	@Override
	protected void onDraw(Canvas canvas) {
		// TODO Auto-generated method stub
		super.onDraw(canvas);
	     int offsetX=0;
	  
	          mIndicatorRect.set(offsetX, indexHeight*curSetion, width,
	                 indexHeight*(curSetion+1));
	          mIndicatorDrawable.setBounds(mIndicatorRect);
	          mIndicatorDrawable.draw(canvas);
	          

	 for (int i=0;i<section.length;i++) {
		 canvas.drawText(section[i], width/2, (i+1)*indexHeight, textPaint);
	 }
	}
	@Override
	protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
		// TODO Auto-generated method stub
		super.onMeasure(widthMeasureSpec, heightMeasureSpec);
		height=getHeight();
		width=getWidth();
		indexHeight=height/section.length;
	}
	@Override
	public boolean onTouchEvent(MotionEvent event) {
		// TODO Auto-generated method stub
		switch (event.getAction()) {
		case MotionEvent.ACTION_DOWN:
		
			float y=event.getY();
			curSetion=getIndex(y);
			setPromptText(curSetion);
			showPopupWindows();
			int position=0;
			if(mIndexer!=null){
			 position=mIndexer.getPositionForSection(curSetion);
			 
			
			  mList.setSelectionFromTop(position, 0);
			}
			
			
			break;
	 case MotionEvent.ACTION_MOVE:
		 
		
		     y=event.getY();
			curSetion=getIndex(y);
			setPromptText(curSetion);
			showPopupWindows();
			  position=0;
			if(mIndexer!=null){
			position=mIndexer.getPositionForSection(curSetion);
			
			  mList.setSelectionFromTop(position, 0);
			}
			
			invalidate();
			
			break;
	  case MotionEvent.ACTION_UP:
	  case MotionEvent.ACTION_CANCEL:
		  disMissPopupWindows();
		break;

		default:
			break;
		}
		
		
		return true;
	}
	
//根据触摸Y值获取字母Index

	private int getIndex(float y){
		for (int i = 1; i <sectionLength; i++) {
			if(y>i*indexHeight&&y<(i+1)*indexHeight){
				return i;
			}	
		}
		
		return 0;
		
	}
    public void setListView(ListView list){
    	Adapter adapter=list.getAdapter();
    	if(adapter instanceof SectionIndexer){
    		mIndexer=(SectionIndexer)adapter;
    		mList=list;
    	}
    	
    }
    private void setPromptText(int sec){
    	mPromptText.setText(section[sec]);
    	
    }
    private void createPopupWindows(){
    	if(mPopupWindow==null){
    		mPopupWindow=new PopupWindow();
    		mPopupWindow.setContentView(mPromptText);
    		mPopupWindow.setHeight(LayoutParams.WRAP_CONTENT);
    		mPopupWindow.setWidth(LayoutParams.WRAP_CONTENT);
    		ColorDrawable d=new ColorDrawable(Color.TRANSPARENT);
    		mPopupWindow.setBackgroundDrawable(d);
    		
    	}
    	
    }
    private  void showPopupWindows(){
    	createPopupWindows();
    	mPopupWindow.showAtLocation(this, Gravity.CENTER, -1, -1);
    	

    }
    private void disMissPopupWindows(){
    	mPopupWindow.dismiss();
    }
}

3.测试Activity

public class MainActivity extends Activity {
	private List<String> items=new ArrayList<String>();

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
       setContentView(R.layout.activity_main);
       ListView list=(ListView)findViewById(R.id.listView1);
       SearchBar bar=(SearchBar)findViewById(R.id.searchbar);
       
       items.add("Action");
       items.add("Adventure");
       items.add("asg");
       items.add("agf");
       items.add("bdd");
       items.add("ball");
       items.add("call");
       items.add("Documentary");
       items.add("Foreign");
       items.add("full");
       items.add("History");
       items.add("Independent");
       items.add("Romance");
       list.setAdapter(new HeaderAdapter(this, R.layout.listitem, R.id.items, items));
       bar.setListView(list);
    
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
      //  getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }
}

4.效果图

今天用手机调试的时候，iphone突然就黑屏了，然后按home键不管用，电源键也不管用；

上网查询，解决如下 ：

第一种方法直接按住电源键，重新开关机；（这种方法试了不管用，接着看下一个）

第二种方法，按住home键和电源键一起十几秒左右；（这种我行的通了，如果再不行看第三方方法）

第三种方法，连接电脑，进入itunes恢复系统。

PorterDuff.Mode的十六种情况可以看APIDemos中的效果，唯一记录一下，做测试时候迷茫的地方

private  void drawIntoBitmap(Bitmap bm) {
        	Canvas canvas = new Canvas(bm);
        	Paint paint = new Paint();
        	InputStream stream = null;
    		try {
    			stream = mContext.getAssets().open("icon.jpg");
    		} catch (IOException e) {
    			// TODO Auto-generated catch block
    			e.printStackTrace();
    		}
    		Bitmap bitmap = BitmapFactory.decodeStream(stream);
    		bitmap = RoundActivity.getRoundCornerBitmap(bitmap);//只是获取一个圆角的图片
    		stream = getResources().openRawResource(R.drawable.ic_launcher);
    		Bitmap src = BitmapFactory.decodeStream(stream);
    		
    		
    		canvas.drawBitmap(bitmap, 100, 100, paint);
    		canvas.drawBitmap(bitmap, 0, 0, paint);
    		//SRC_OVER与SRC模式相比，主要区别SRC_OVER是会有透明度影响。而DST的话，则是src区域不显示，不像SRC模式，只是src区域所占的地方，det区对应地方被覆盖
		//Over 类型的MODE只有Config为ARGB,以及Alph8类型的位图才会有效果
		paint.setXfermode(new PorterDuffXfermode(Mode.SRC_OVER));
		//只有src占用的区间才会用到Xfermode模式进行运算，而不是整个Canvas区域生效。当然可以指定dst区域.或着如下边注释行的方法，设置了dirst区域。
		// canvas.drawBitmap(src,new Rect(0, 0, src.getWidth(), src.getHeight()),new Rect(0, 0, 200 , 200),paint);
		canvas.drawBitmap(src, 0, 0,paint); 
		paint.setARGB(0x80, 0x0, 0xff, 0x0); 
		paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_OVER)); 
		paint.setTextSize(60)
		;// paint.setShader(mShader);
		paint.setTextAlign(Paint.Align.CENTER);//如果是这个属性，则drawtext中的x,y坐标指的是文字所占区域的中心
		Paint.FontMetrics fm = paint.getFontMetrics();
		//如果是文字的话，XFermode设置后，只有文字的轨迹占用的地方才会生效
		canvas.drawText("text", bm.getWidth()/2, (bm.getWidth()-fm.ascent)/2, paint); 
		
}

如图

2、AvoidXfermode

		private void drawInBitmapAvoid(Bitmap bm) {
			Canvas canvas = new Canvas(bm);
			Paint paint = new Paint();
			canvas.drawBitmap(mBitmap, new Rect(0, 0, mBitmap.getWidth(), mBitmap.getHeight()), new Rect(0, 0, bm.getWidth(), bm.getHeight()), paint);
			paint.setARGB(0xff, 0xff, 0x00, 0x00);
			//Mode.AVOID 模式下是给op-color不一样的地方才绘制
			// 如果tolerance 即误差为0，或者说完全不一样，才会绘制
			// 如果tolerance 即误差为255，或者说稍微不一样，就可以绘制
			//这边有点拗口，看另外一个模式就明白了
			paint.setXfermode(new AvoidXfermode(0xff505050, 0, AvoidXfermode.Mode.AVOID));;
			canvas.drawCircle(0, 0, bm.getWidth()/2, paint);
			paint.setXfermode(new AvoidXfermode(0xff505050, 255, AvoidXfermode.Mode.AVOID));;
			canvas.drawCircle(bm.getWidth(), 0, bm.getWidth()/2, paint);
			// 如果是Mode.TARGET模式，只给与op-color一样的像素点上绘制
			//如果tolerance为0，即完全一样，才会给这个像素点绘制
			//如果tolerance为255，即稍微一样一点，就会给这个像素点绘制
			paint.setXfermode(new AvoidXfermode(0xff505050, 0, AvoidXfermode.Mode.TARGET));;
			canvas.drawCircle(0, bm.getHeight(), bm.getWidth()/2, paint);
			paint.setXfermode(new AvoidXfermode(0xff505050, 255, AvoidXfermode.Mode.TARGET));;
			canvas.drawCircle(bm.getWidth(), bm.getHeight(), bm.getWidth()/2, paint);
		}

如图

3、PixelXorXfermode

文档中说PixelXorXfermode implements a simple pixel xor (op ^ src ^ dst).  我自认为模块一和模块二效果会一样，但是实验结果不同。

这个类，我完全被他打败了。测试了一下午也没测出规律和原因来，如果有懂的，望不吝赐教

而且经常不同的是R值和B值互换，有时候又正常。真不知道哪里错了

        private void drawInBitmapPixel(Bitmap bm) {
			Canvas canvas = new Canvas(bm);
			Paint paint = new Paint();
			int dst = 0xff00ffff;
			paint.setColor(dst);
			Rect rect = new Rect(0, 0, bm.getWidth(), bm.getHeight()/2-8);
			canvas.drawRect(rect, paint);
			int src = 0xffffff00;
			int opr = 0xffff0000;
			
			//模块一
			paint.setXfermode(new PixelXorXfermode(opr));
			paint.setColor(src);
			canvas.drawRect(rect, paint);
			//模块二
			paint.setXfermode(null);
			int result = opr^src^dst;
			/*//R和B 互换  0x ff ff ff ff
			// 取B值
			int b = result&0x000000ff;
			//取R值
			int r = result&0x00ff0000;
			//移动到对应位置
			b = b<<16;
			r = r>>16;
			//过滤RB值
			result = result&0xff00ff00;
			//放入RB值
			result |= r;
			result |= b;*/
			paint.setColor(result);
			rect = new Rect(0,bm.getHeight()/2+8,bm.getWidth(),bm.getHeight());
			canvas.drawRect(rect, paint);
			
			paint.setXfermode(null);
			paint.setTextSize(15);
			paint.setTextAlign(Align.CENTER);
			canvas.drawText("^color="+Integer.toHexString(paint.getColor()), bm.getWidth()/2, (bm.getHeight()-paint.getFontMetrics().ascent)/2, paint);
		}