Android之使用Volley框架在ListView中加载大量图片 _listview

不操千曲而后晓声，观千剑而后识器。这篇文章主要讲述Android之使用Volley框架在ListView中加载大量图片相关的知识，希望能为你提供帮助。
1.listview 中的条目要用 Volley 中的 NetworkImageView,如果直接用ImageView也可以,但是要在getView方法中使用url地址设置为imageView的tag标记

< ?xml version="1.0" encoding="utf-8"?> < LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" > < com.android.volley.toolbox.NetworkImageView android:id="@+id/userimage" android:layout_width="100dp" android:layout_height="100dp" /> < /LinearLayout>

2.新建图片缓存类 BitmapCache

import android.graphics.Bitmap; import android.support.v4.util.LruCache; import com.android.volley.toolbox.ImageLoader.ImageCache; public class BitmapCache implements ImageCache { private LruCache< String, Bitmap> mCache; public BitmapCache() { int maxSize = 4 * 1024 * 1024; mCache = new LruCache< String, Bitmap> (maxSize) { @Override protected int sizeOf(String key, Bitmap bitmap) { //return bitmap.getByteCount(); // > api12 才能用 return bitmap.getRowBytes() * bitmap.getHeight(); } }; }@Override public Bitmap getBitmap(String url) { return mCache.get(url); }@Override public void putBitmap(String url, Bitmap bitmap) { if (bitmap != null) { mCache.put(url, bitmap); } } }

【Android之使用Volley框架在ListView中加载大量图片】3.adapater代码

import android.content.Context; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.BaseAdapter; import com.android.volley.RequestQueue; import com.android.volley.toolbox.ImageLoader; import com.android.volley.toolbox.NetworkImageView; import com.android.volley.toolbox.Volley; public class MyAdapter extends BaseAdapter { private String[] list; private Context context; private RequestQueue queue; private ImageLoader imageLoader; public MyAdapter(Context context, String[] list) { this.context = context; this.list = list; queue = Volley.newRequestQueue(context); imageLoader = new ImageLoader(queue, new BitmapCache()); }@Override public int getCount() { return list.length; }@Override public Object getItem(int position) { return list[position]; }@Override public long getItemId(int position) { return position; }@Override public View getView(int position, View convertView, ViewGroup parent) { ViewHolder holder = null; if (convertView == null) { holder = new ViewHolder(); convertView = LayoutInflater.from(context).inflate(R.layout.list_item, null); holder.img = (NetworkImageView) convertView.findViewById(R.id.userimage); convertView.setTag(holder); } else { holder = (ViewHolder) convertView.getTag(); }final String imgUrl = list[position]; if (imgUrl != null & & !imgUrl.equals("")) { holder.img.setDefaultImageResId(R.drawable.ic_launcher); holder.img.setErrorImageResId(R.drawable.ic_launcher); holder.img.setImageUrl(imgUrl, imageLoader); }return convertView; }class ViewHolder { NetworkImageView img; } }