ListView优化

在获得布局填充view的时候我们一般用到的是View.inflate()方法，我们每滑动一次getview就要执行一次同样，也要填充一次布局，

listview只能显示屏幕那么多的内容，而不用的不会马上销毁而是放到缓存里，这样我们就可以利用这点来进行优化，当有缓存的时候我

们就要用到缓存，不用重新调用View.inflate()

代码实现

// 返回视图,这个方法很主要
    public View getView(int position, View arg, ViewGroup arg2) {
        View view = null;
        
　　　　//判断是否有缓存，如果没有填充布局，有的话利用缓存。不管是缓存还是新获取的都要重新设置内容
　　　　if(arg==null){
            
            view = View.inflate(context, R.layout.lisviewt_item1, null);
        }else{
            view = arg;
        }
        
        FriendBean fb = data.get(position);
        ImageView img = (ImageView) view.findViewById(R.id.iv);
        TextView name = (TextView) view.findViewById(R.id.tv_1);
        TextView gexing = (TextView) view.findViewById(R.id.tv_2);
        img.setImageResource(fb.getImgID());
        name.setText(fb.getName());
        gexing.setText(fb.getGexing());
        return view;
    }

private class AppAdapter extends BaseAdapter {

        @Override
        public int getCount() {
            // TODO Auto-generated method stub
            return appMessage.size();
        }

        @Override
        public Object getItem(int arg0) {
            // TODO Auto-generated method stub
            return arg0;
        }

        @Override
        public long getItemId(int arg0) {
            // TODO Auto-generated method stub
            return arg0;
        }

        @Override
        public View getView(int position, View arg1, ViewGroup arg2) {
            View v = null;
            ViewHolder viewHolder;
            if (arg1 == null) {
                v = View.inflate(AppManagerActivity.this,
                        R.layout.item_app_show, null);
                viewHolder = new ViewHolder();
                viewHolder.tv_name=(TextView) v.findViewById(R.id.app_item_tv_name);
                viewHolder.tv_location = (TextView) v.findViewById(R.id.app_item_tv_location);
                viewHolder.img_icon = (ImageView) v.findViewById(R.id.app_item_img_icon);
                //对应关系一致
                v.setTag(viewHolder);
                
                
            } else {
                v = arg1;
                viewHolder = (ViewHolder) v.getTag();
            }    
            AppInfo app = appMessage.get(position);
            viewHolder.img_icon.setImageDrawable(app.getIcon());
            viewHolder.tv_name.setText(app.getName());
            if(app.isRow()){
                viewHolder.tv_location.setText("内部存储程序");
            }else{
                viewHolder.tv_location.setText("外部存储程序");
            }
            return v;
        }

    }

    static class ViewHolder {
        ImageView img_icon;
        TextView tv_name;
        TextView tv_location;
    }