android下对于Cursor的中文拼音排序实现

转自http://jamking.iteye.com/blog/1019303

android下面需要对数据库某列的内容,按照中文拼音的顺序来排序。
baidu了下，发现常见的方式是要在数据库增加一列来存放拼音，专门用该列来排序，比如联系人就是用此方式实现的。
换google,发现有邮件中说,可以实现CursorWrapper,来达到排序功能。
具体看 How to do sorting on cursor?
http://groups.google.com/group/android-developers/browse_thread/thread/f1fc3e0fc87a3fc6

主要思路是:override move系列的方法,让cursor以自己想要的顺序来移动,从而达到对cursor排序的目的。
比如数组A0里有 4(0),3(1),1(2),2(3),括号内为位置,排序后用数据记录A1:1(2),2(3),3(1),4(0)
要访问第一个元素,则访问A1[0]得到1(2),根据(2)找到在A0中的实际位置2,即1(2)

参考了下系统的CursorWrapper和AbstractCursor代码实现,另外有时间可以顺带了解下MatrixCursor

直接上代码

import java.text.Collator;  
import java.util.ArrayList;  
import java.util.Collections;  
import java.util.Comparator;  
  
import android.database.Cursor;  
import android.database.CursorWrapper;  
  
public class SortCursor extends CursorWrapper{  
    Cursor mCursor;  
    ArrayList<SortEntry> sortList = new ArrayList<SortEntry>();  
    int mPos = 0;  
      
    public class SortEntry {  
        public String key;  
        public int order;  
    }  
      
    //直接初始化,加快比较速度,在G3上从3s->0.2s  
    @SuppressWarnings("rawtypes")  
    private Comparator cmp = Collator.getInstance(java.util.Locale.CHINA);  
      
    @SuppressWarnings("unchecked")    
    public Comparator<SortEntry> comparator = new Comparator<SortEntry>(){        
        @Override  
        public int compare(SortEntry entry1, SortEntry entry2) {              
            return cmp.compare(entry1.key, entry2.key);         
        }     
    };  
  
    public SortCursor(Cursor cursor,String columnName) {          
        super(cursor);  
        MusicLog.i("MediaScanner", "start-----------");  
        // TODO Auto-generated constructor stub  
        mCursor = cursor;  
        if(mCursor != null && mCursor.getCount() > 0) {  
            int i = 0;  
            int column = cursor.getColumnIndexOrThrow(columnName);  
            for(mCursor.moveToFirst();!mCursor.isAfterLast();mCursor.moveToNext(),i++){  
                SortEntry sortKey = new SortEntry();  
                sortKey.key = cursor.getString(column);  
                sortKey.order = i;  
                sortList.add(sortKey);  
            }  
        }  
        MusicLog.i("MediaScanner", "start1-----------");  
        //排序  
        Collections.sort(sortList,comparator);  
        MusicLog.i("MediaScanner", "start2-----------");  
    }  
      
    public boolean moveToPosition(int position)  
    {  
        if(position >= 0 && position < sortList.size()){  
            mPos = position;  
            int order = sortList.get(position).order;  
            return mCursor.moveToPosition(order);  
        }  
        if(position < 0){  
            mPos = -1;  
        }  
        if(position >= sortList.size()){  
            mPos = sortList.size();  
        }  
        return mCursor.moveToPosition(position);          
    }  
      
    public boolean moveToFirst() {        
        return moveToPosition(0);  
    }  
      
    public boolean moveToLast(){  
        return moveToPosition(getCount() - 1);  
    }  
      
    public boolean moveToNext() {                 
        return moveToPosition(mPos+1);  
    }  
      
    public boolean moveToPrevious() {         
        return moveToPosition(mPos-1);  
    }  
      
    public boolean move(int offset) {         
        return moveToPosition(mPos + offset);  
    }  
      
    public int getPosition() {        
        return mPos;  
    }  
}  

参考文章
Android 对汉字字符串按照拼音排序
http://hi.baidu.com/luyanlong1/blog/item/2c31b51d938b79ecae5133fc.html
The Busy Coder's Guide to Android Development 这本书应该也不错,推荐下