Android listView 中响应Button点击事件

public class Task_list_single_item_adapter extends BaseAdapter
{

LayoutInflater inflater;
Context context;
public Task_list_single_item_adapter(Context context){
this.context=context;
inflater=LayoutInflater.from(context);
}
@Override
public int getCount()
{
return 2;
}

@Override
public Object getItem(int position)
{
return null;
}

@Override
public long getItemId(int position)
{
return position;
}

@Override
public View getView(int position, View convertView, ViewGroup parent)
{
final Holder holder;
if(convertView!=null)
{
holder=(Holder) convertView.getTag();
}else {
holder=new Holder();
convertView=inflater.inflate(R.layout.download_management_item, null);
holder.pause=(Button) convertView.findViewById(R.id.dmi_ib1_pause);
holder.trys=(Button) convertView.findViewById(R.id.dmi_ib2_recover);
holder.install=(Button) convertView.findViewById(R.id.dmi_ib3_install);
convertView.setTag(holder);
}
OnClickListener listener=new OnClickListener(){
@Override
public void onClick(View v)
{
if(v==holder.pause){
Toast.makeText(context, "pause", Toast.LENGTH_SHORT).show();
holder.pause.setVisibility(View.GONE);
holder.trys.setVisibility(View.VISIBLE);
holder.install.setVisibility(View.GONE);
}
if(v==holder.trys){
Toast.makeText(context, "try", Toast.LENGTH_SHORT).show();
holder.pause.setVisibility(View.VISIBLE);
holder.trys.setVisibility(View.GONE);
holder.install.setVisibility(View.GONE);
}
if(v==holder.install)
Toast.makeText(context, "install", Toast.LENGTH_SHORT).show();

}
};
holder.pause.setOnClickListener(listener);
holder.trys.setOnClickListener(listener);
holder.install.setOnClickListener(listener);
return convertView;
}
class Holder{
public Button pause;
public Button trys;
public Button install;
}
}