Listview滑动时不加载数据，停下来时加载数据，让App更优

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;/** * */{Context context;LayoutInflater inflater;List<UserEnity> lists;private boolean scrollState=false;(boolean scrollState) {this.scrollState = scrollState;}public MyAdapter(Context context, List<UserEnity> lists) {this.context=context;this.inflater=LayoutInflater.from(context);this.lists=lists;}() {return lists!=null?lists.size():0;}@Overridepublic Object getItem(int position) {return lists.get(position);}(int position) {return position;}@Overridepublic 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:

scrollState=false;(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);}设置监听

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

(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nameTextView 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——urlImageLoader.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

留下许多叫知识和情感的东西握在手里。