數據源配置（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("加載中");
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;
}
}
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這個Adapter中重要的代碼如下:
//定義當前listview是否在滑動狀態
private boolean scrollState=false;
public void setScrollState(boolean scrollState) {
this.scrollState = scrollState;
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//實體類
UserEnity userEnity=lists.get(position);
if (!scrollState){//如果當前不是滑動的狀態，我們填充真數據
//填充數據
viewHolder.tv_name.setText(userEnity.getName());
//設置Tag中數據爲空表示數據已填充
viewHolder.tv_name.setTag(null);
//加載圖片
ImageLoader.getInstance().displayImage(img_url,viewHolder.iv_icon);
//設置tag爲1表示已加載過數據
viewHolder.iv_icon.setTag("1");
}else{//如果當前是滑動的狀態，我們填充假數據
viewHolder.tv_name.setText("加載中");
//將數據name保存在Tag當中
viewHolder.tv_name.setTag(userEnity.getName());
//將數據image_url保存在Tag當中
viewHolder.iv_icon.setTag(img_url);
//設置默認顯示圖片（最好是本地資源的圖片）
viewHolder.iv_icon.setImageResource(R.mipmap.ic_launcher);
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設置監聽
ok,我們在看看Activity中的代碼，主要是監聽listview的onscrolllistener方法
@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
switch (scrollState){
case AbsListView.OnScrollListener.SCROLL_STATE_IDLE://停止滾動
{
//設置爲停止滾動
myAdapter.setScrollState(false);
//當前屏幕中listview的子項的個數
int count = view.getChildCount();
Log.e("MainActivity",count+"");
for (int i = 0; i < count; i++) {
//獲取到item的name
TextView tv_name = (TextView) view.getChildAt(i).findViewById(R.id.main_item_tv_name);
//獲取到item的頭像
ImageView iv_show= (ImageView) view.getChildAt(i).findViewById(R.id.main_item_iv_icon);
if (tv_name.getTag() != null) { //非null說明需要加載數據
tv_name.setText(tv_name.getTag().toString());//直接從Tag中取出我們存儲的數據name並且賦值
tv_name.setTag(null);//設置爲已加載過數據
}
if (!iv_show.getTag().equals("1")){//!="1"說明需要加載數據
String image_url=iv_show.getTag().toString();//直接從Tag中取出我們存儲的數據image——url
ImageLoader.getInstance().displayImage(image_url, iv_show);//顯示圖片
iv_show.setTag("1");//設置爲已加載過數據
}
}
break;
}
case AbsListView.OnScrollListener.SCROLL_STATE_FLING://滾動做出了拋的動作
{
//設置爲正在滾動
myAdapter.setScrollState(true);
break;
}
case AbsListView.OnScrollListener.SCROLL_STATE_TOUCH_SCROLL://正在滾動
{
//設置爲正在滾動
myAdapter.setScrollState(true);
break;
}
}
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最後記得給listview加上滑動的監聽
listview.setOnScrollListener(this);- 1
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效果
