联系人字母索引实现

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