Android Listview滑动时不加载数据，停下来时加载数据，让App更优

转载：http://blog.csdn.net/yy1300326388/article/details/45153813

数据源配置（Adapter）

package com.zhengsonglan.listview_loading.adapter;import android.content.Context;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.BaseAdapter;import android.widget.ImageView;import android.widget.TextView;import com.nostra13.universalimageloader.core.ImageLoader;import com.zhengsonglan.listview_loading.R;import com.zhengsonglan.listview_loading.entity.UserEnity;import java.util.List;/** * */public class MyAdapter extends BaseAdapter {    Context context;    LayoutInflater inflater;    List<UserEnity> lists;    private  boolean scrollState=false;    public void setScrollState(boolean scrollState) {        this.scrollState = scrollState;    }    public MyAdapter(Context context, List<UserEnity> lists) {        this.context=context;        this.inflater=LayoutInflater.from(context);        this.lists=lists;    }    @Override    public int getCount() {        return lists!=null?lists.size():0;    }    @Override    public Object getItem(int position) {        return lists.get(position);    }    @Override    public long getItemId(int position) {        return position;    }    @Override    public View getView(int position, View convertView, ViewGroup parent) {        ViewHolder viewHolder;        if (convertView == null) {            convertView=inflater.inflate(R.layout.main_item,null,true);            viewHolder=new ViewHolder();            viewHolder.iv_icon= (ImageView) convertView.findViewById(R.id.main_item_iv_icon);            viewHolder.tv_name= (TextView) convertView.findViewById(R.id.main_item_tv_name);            convertView.setTag(viewHolder);        } else {            viewHolder= (ViewHolder) convertView.getTag();        }        UserEnity userEnity=lists.get(position);        String img_url=userEnity.getIcon();        if (!scrollState){            viewHolder.tv_name.setText(userEnity.getName());            viewHolder.tv_name.setTag(null);            ImageLoader.getInstance().displayImage(img_url,viewHolder.iv_icon);            viewHolder.iv_icon.setTag("1");        }else{            viewHolder.tv_name.setText("加载中");            viewHolder.tv_name.setTag(userEnity.getName());            viewHolder.iv_icon.setTag(img_url);            viewHolder.iv_icon.setImageResource(R.mipmap.ic_launcher);        }        return convertView;    }    static class ViewHolder{        TextView tv_name;        ImageView iv_icon;    }}

这个Adapter中重要的代码如下:

//定义当前listview是否在滑动状态private  boolean scrollState=false;public void setScrollState(boolean scrollState) {    this.scrollState = scrollState;}

//实体类UserEnity userEnity=lists.get(position);if (!scrollState){//如果当前不是滑动的状态，我们填充真数据            //填充数据            viewHolder.tv_name.setText(userEnity.getName());            //设置Tag中数据为空表示数据已填充            viewHolder.tv_name.setTag(null);            //加载图片            ImageLoader.getInstance().displayImage(img_url,viewHolder.iv_icon);            //设置tag为1表示已加载过数据            viewHolder.iv_icon.setTag("1");}else{//如果当前是滑动的状态，我们填充假数据            viewHolder.tv_name.setText("加载中");            //将数据name保存在Tag当中            viewHolder.tv_name.setTag(userEnity.getName());            //将数据image_url保存在Tag当中            viewHolder.iv_icon.setTag(img_url);            //设置默认显示图片（最好是本地资源的图片）            viewHolder.iv_icon.setImageResource(R.mipmap.ic_launcher);}

我们在看看Activity中的代码，主要是监听listview的onscrolllistener方法

@Override    public void onScrollStateChanged(AbsListView view, int scrollState) {        switch (scrollState){            case AbsListView.OnScrollListener.SCROLL_STATE_IDLE://停止滚动            {                //设置为停止滚动                myAdapter.setScrollState(false);                //当前屏幕中listview的子项的个数                int count = view.getChildCount();                Log.e("MainActivity",count+"");                for (int i = 0; i < count; i++) {                    //获取到item的name                    TextView tv_name = (TextView) view.getChildAt(i).findViewById(R.id.main_item_tv_name);                    //获取到item的头像                    ImageView iv_show= (ImageView) view.getChildAt(i).findViewById(R.id.main_item_iv_icon);                    if (tv_name.getTag() != null) { //非null说明需要加载数据                        tv_name.setText(tv_name.getTag().toString());//直接从Tag中取出我们存储的数据name并且赋值                        tv_name.setTag(null);//设置为已加载过数据                    }                    if (!iv_show.getTag().equals("1")){//!="1"说明需要加载数据                        String image_url=iv_show.getTag().toString();//直接从Tag中取出我们存储的数据image——url                        ImageLoader.getInstance().displayImage(image_url, iv_show);//显示图片                        iv_show.setTag("1");//设置为已加载过数据                    }                }                break;            }            case AbsListView.OnScrollListener.SCROLL_STATE_FLING://滚动做出了抛的动作            {                //设置为正在滚动                myAdapter.setScrollState(true);                break;            }            case AbsListView.OnScrollListener.SCROLL_STATE_TOUCH_SCROLL://正在滚动            {                //设置为正在滚动                myAdapter.setScrollState(true);                break;            }        }    }

最后记得给listview加上滑动的监听

listview.setOnScrollListener(this);

效果