ListView设置快速滑动时不加载图片

设置ListView 快速滑动不加载要设置滑动监听OnScrollListener， 当快速滑动是设置标志位不请求网络

这个也属于listview优化的一步

设置监听器

package com.example.listview_01;

import android.widget.AbsListView;
import android.widget.BaseAdapter;
import android.widget.AbsListView.OnScrollListener;

public class ListViewOnscrollLister implements OnScrollListener {

    // 添加标志位
    public static boolean isLoadImg = true;

    public BaseAdapter basedapter;

    public ListViewOnscrollLister(BaseAdapter basedapter) {
        this.basedapter = basedapter;
    }

    @Override
    public void onScrollStateChanged(AbsListView view, int scrollState) {
        switch (scrollState) {
        case OnScrollListener.SCROLL_STATE_FLING:
            isLoadImg = false;
            break;
        case OnScrollListener.SCROLL_STATE_IDLE:
            isLoadImg = true;
            basedapter.notifyDataSetChanged();
            break;
        case OnScrollListener.SCROLL_STATE_TOUCH_SCROLL:
            isLoadImg = false;
            break;

        }

    }

    @Override
    public void onScroll(AbsListView view, int firstVisibleItem,
            int visibleItemCount, int totalItemCount) {
        // TODO Auto-generated method stub

    }

}

adapter设置

package com.example.listview_01;

import java.util.List;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

import android.content.Context;
import android.os.Handler;
import android.util.Log;
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.example.listview_01.ImageLoader.ImgResult;

public class ImgAdapter extends BaseAdapter {

    private Context context;
    private List<ViewItem> list;
    private LayoutInflater inflater;
    private BlockingQueue<Runnable> workQueue = new ArrayBlockingQueue<Runnable>(
            200);
    // 设置线程线程池
    private ThreadPoolExecutor executor = new ThreadPoolExecutor(4, 10, 200,
            TimeUnit.SECONDS, workQueue);
    private Handler handler = new Handler() {
        public void handleMessage(android.os.Message msg) {
            ImgResult imgresult = (ImgResult) msg.obj;
            imgresult.img.setImageBitmap(imgresult.bitmap);
        };
    };

    public ImgAdapter(Context context, List<ViewItem> list) {
        this.context = context;
        this.list = list;
        inflater = LayoutInflater.from(context);
    }

    @Override
    public int getCount() {
        return list.size();
    }

    @Override
    public Object getItem(int position) {
        return list.get(position);
    }

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

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        // TODO Auto-generated method stub
        ImgHolder imgHolder = null;
        if (null == convertView) {
            convertView = inflater.inflate(R.layout.activity_img, null);
            imgHolder = new ImgHolder(convertView);
            convertView.setTag(imgHolder);
        } else {
            imgHolder = (ImgHolder) convertView.getTag();
        }
        ViewItem item = list.get(position);
        imgHolder.addressTxt.setText(item.getAddress());
        imgHolder.titleTxt.setText(item.getTitle());
        // 设置快速滚动不加载图片停止滚动时加载图片
        if (MainActivity.onscroll.isLoadImg) {
75             executor.submit(new ImageLoader(item.getImgUrl(), handler,
76                     imgHolder.imgView));
77         }
        return convertView;
    }

    class ImgHolder {
        public TextView titleTxt;
        public TextView addressTxt;
        public ImageView imgView;

        public ImgHolder(View convertView) {
            titleTxt = (TextView) convertView.findViewById(R.id.title);
            addressTxt = (TextView) convertView.findViewById(R.id.content);
            imgView = (ImageView) convertView.findViewById(R.id.imageView1);
        }
    }
}

线程下载图片

package com.example.listview_01;

import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Handler;
import android.os.Message;
import android.widget.ImageView;

public class ImageLoader implements Runnable {

    private String path;
    private Handler handler;
    private ImageView imgView;

    public ImageLoader(String url, Handler handler, ImageView imgView) {
        this.path = url;
        this.handler = handler;
        this.imgView = imgView;
    }

    @Override
    public void run() {
        try {
            URL url = new URL(path);
            HttpURLConnection connection = (HttpURLConnection) url
                    .openConnection();
            connection.setDoInput(true);
            connection.setRequestMethod("GET");
            InputStream is = connection.getInputStream();
            Bitmap bitmap = BitmapFactory.decodeStream(is);
            Message msg = Message.obtain();
            msg.obj = new ImgResult(imgView, bitmap);
            handler.sendMessage(msg);
            is.close();
            connection.disconnect();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    public class ImgResult {
        public ImageView img;
        public Bitmap bitmap;

        public ImgResult(ImageView imgs, Bitmap bitmaps) {
            img = imgs;
            bitmap = bitmaps;
        }
    }
}

ListView 设置监听

adapter = new ImgAdapter(this, list);
listView.setAdapter(adapter);
onscroll = new ListViewOnscrollLister(adapter);
listView.setOnScrollListener(onscroll);