Listview Adapter 优化总结

1.使用Holder

2.使用view.setTag(),view.getTag()

 ListView中Button点击事件的实现

  ListView 中实现Item中的Button事件，在实现Button事件时，最关键的事情是，当前button对于的Item的唯一标识，而如何保存这唯一标识到button中呢，

  在View中包含了setTag 和getTag 一对方法，同过这样的方法可以在View’绑定时，把Item中的唯一标识 保存到Button的Tag中，并在Button的点击事件中读取标识。

例1：（来自网上）

/* */
public class CursorAdapter_ExecuteTheme extends CursorAdapter {
    private LayoutInflater mInflater;
    private Context mContext;
    TextView theme_id;
    public CursorAdapter_ExecuteTheme(Context context, Cursor c) {
        super(context, c);
        mContext = context;
        mInflater = LayoutInflater.from(context);
 
    }
     
    @Override
    public void bindView(View view, Context context, Cursor cursor) {
         
        theme_id = (TextView) view.findViewById(R.id.theme_id);
        TextView txt_themetitle = (TextView) view.findViewById(R.id.txt_themetitle);
        TextView txt_themedescribe=(TextView) view.findViewById(R.id.txt_themedescribe);
        ImageView img_exbut=(ImageView)view.findViewById(R.id.imgv_exbut);
        theme_id.setText(cursor.getString(0));
        txt_themetitle.setText(cursor.getString(2));
         
        //  //pk as _id,catalogFK,Name,3GuessCount,4State,5CurIndex,Describe from CLTheme
        txt_themedescribe.setText("已做("+cursor.getString(5)+")全部("+cursor.getString(3) +")");
        int state=cursor.getInt(4);
        img_exbut.setTag(cursor.getString(0));
        if((state==ProjectConstant.ThemeState_BEGGING)||(state==ProjectConstant.ThemeState_NONE))//主题开始
        {
            if(state==ProjectConstant.ThemeState_BEGGING)
            img_exbut.setImageResource(R.drawable.cl_goon);
             
         
            img_exbut.setOnClickListener(new  ImageView.OnClickListener()
            {
                public void onClick(View v){
                   SoundManager.Instance.playSound("SOUND_WELCOME");
                   String id=v.getTag().toString();
                   //获取当前主题状态
                   //创建当前测试业务逻辑并加载选择的主题数据
                   ExerciseBussiness.SelectTheme(id,ProjectConstant.ThemeType_Classic ,mContext);
                   Intent i = new Intent((Activity)mContext,ExerciseGuess.class);
                   i.putExtra("themefk",id);
                   mContext.startActivity(i);   
                   ((Activity)mContext).finish();
                }
            });
        }else if(state==ProjectConstant.ThemeState_END)//重新做
        {
            img_exbut.setImageResource(R.drawable.cl_redo);
            img_exbut.setOnClickListener(new  ImageView.OnClickListener()
            {
                 public void onClick(View v){
                      SoundManager.Instance.playSound("SOUND_WELCOME");
                      String id=v.getTag().toString();
                       
                      ExerciseBussiness.ReDoTheme(id ,mContext); //重新做题
                      Intent i = new Intent((Activity)mContext,ExerciseGuess.class);
                      i.putExtra("themefk",id);
                      mContext.startActivity(i);    
                      ((Activity)mContext).finish();
                 }
                  
            });
        }
    }
     
    @Override
    public View newView(Context arg0, Cursor arg1, ViewGroup arg2) {
        return mInflater.inflate(R.layout.sub_extheme_item, arg2, false);
    }       
     
     
}

例2（自己的）

class CityListAdapter extends BaseAdapter {
		private Context context;
		private List<City> datas;
		private List<City> downloadCitys;
	

		public CityListAdapter(Context context, List<City> citys) {
			this.datas = citys;
			Log.w("dates", datas.size() + "");
			this.context = context;
			downloadCitys=(List<City>)AppCache.get("DOWNLOAD_CITYS");
		}

		@Override
		public int getCount() {
			return datas.size();
		}

		@Override
		public Object getItem(int position) {
			return datas.get(position);
		}

		@Override
		public long getItemId(int position) {
			return position;
		}
		private CityListItem item;
		@Override
		public View getView(int position, View view, ViewGroup group) {
			ViewHolder viewHolder;
			item=null;
			if(view==null){
				viewHolder=new ViewHolder();
				view = LayoutInflater.from(context).inflate(R.layout.city_listview,
						null);
				viewHolder.tvCityName = (TextView) view.findViewById(R.id.itemTitle);
				viewHolder.btDownload = (Button) view.findViewById(R.id.id_download);
				viewHolder.btDownload.setOnClickListener(new OnClickListener() {
					@Override
					public void onClick(View v) {
						ViewHolder _viewHolder=(ViewHolder)v.getTag();
						download(_viewHolder);
					}
				});
				view.setTag(viewHolder);
			}else {
				viewHolder=(ViewHolder)view.getTag();
			}
			item=itemMap.get(position);
			if(item==null){
				item=new CityListItem(datas.get(position));
				updateView(item);
				itemMap.put(position, item);
			}
			viewHolder.tvCityName.setText(item.tvCityName);
			viewHolder.btDownload.setText(item.btDownload);
			viewHolder.position=position;
			viewHolder.btDownload.setTag(viewHolder);//标识 view对象
			
			return view;
		}
		
	}

网摘 ：ListView 编程: Adapter 何方神圣？

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      （android实战)自定义CursorAdapter,实现ListView中动态加载button,和点击事件