先说一下思路，开始让一张放在res/drawable里的图片代替网络图片，加进ListItem，现在显示的就是本地图片，然后新开一个线程循环下载网络图片，每下完一张，替换原来显示的本地图片，更新ListView。
刚开始做的时候，乱配器用的是SimpleAdapter，但是后来发现，SimpleAdapter只能加载事先放在res/drawable，不能加载Bitmap，或者是Drawable，于是写了个适配器来继承SimpleAdapter，加入Bitmap支持，完美实现以上功能。
final ListView list = (ListView) findViewById(R.id.favlv);
list.setDivider(null);
list.setOnItemClickListener(Click);
MyAdapter listItemAdapter;
ArrayList<HashMap<String, Object>> listItem = new ArrayList<HashMap<String, Object>>();
cursor=db.query("fav",new String[]{"id","title","url","thumb"},null,null,null,null,"id DESC");
UrlArr.clear();
ThumbArr.clear();
ItemID.clear();
if(cursor.getCount()>0){
nofav.setVisibility(View.INVISIBLE);
}
while(cursor.moveToNext()){
HashMap<String, Object> map = new HashMap<String, Object>();
map.put("ItemImage",R.drawable.load);//图像资源的ID
map.put("ItemTv",cursor.getString(1));
listItem.add(map);
UrlArr.add(cursor.getString(2));
ThumbArr.add(cursor.getString(3));
ItemID.add(cursor.getString(0));
}
cursor.close();
//以上内容是读取数据库，并把数据加到listItem上，没有数据库的自己看着改，ThumbArr存放的是图片URL，另两个是我项目里用的
listItemAdapter = new MyAdapter(this,listItem,R.layout.favlv,new String[] {"ItemImage","ItemTv"},new int[] {R.id.ItemImage,R.id.ItemTv});
list.setAdapter(listItemAdapter);
list.setOnCreateContextMenuListener(MenuLis);
//新开线程循环下载图片
new Thread(){
@SuppressWarnings("unchecked")
public void run(){
int i=0;
while(i<ThumbArr.size()){
try {
URL uri = new URL(ThumbArr.get(i));
URLConnection conn = uri.openConnection();
conn.connect();
InputStream is = conn.getInputStream();
Bitmap bmp=BitmapFactory.decodeStream(is);
is.close();
HashMap<String, Object> map = (HashMap<String, Object>)listItemAdapter.getItem(i);
map.put("ItemImage",bmp);
handler.sendEmptyMessage(0);//这个是更新通知就是listItemAdapter.notifyDataSetChanged();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
i++;
}
}
}.start();
下面的是MyAdapter适配器代码：
package com.BottomMenu;
import java.util.List;
import java.util.Map;
import android.content.Context;
import android.graphics.Bitmap;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Checkable;
import android.widget.ImageView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
public class MyAdapter extends SimpleAdapter {
private int[] mTo;
private String[] mFrom;
private ViewBinder mViewBinder;
private List<? extends Map<String, ?>> mData;
private int mResource;
private int mDropDownResource;
private LayoutInflater mInflater;
public MyAdapter(Context context,
List<? extends Map<String, ?>> data, int resource, String[] from,
int[] to) {
super(context, data, resource, from, to);
mData = data;
mResource = mDropDownResource = resource;
mFrom = from;
mTo = to;
mInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
/**
* @see android.widget.Adapter#getView(int, View, ViewGroup)
*/
public View getView(int position, View convertView, ViewGroup parent) {
return createViewFromResource(position, convertView, parent, mResource);
}
private View createViewFromResource(int position, View convertView,
ViewGroup parent, int resource) {
View v;
if (convertView == null) {
v = mInflater.inflate(resource, parent, false);
final int[] to = mTo;
final int count = to.length;
final View[] holder = new View[count];
for (int i = 0; i < count; i++) {
holder[i] = v.findViewById(to[i]);
}
v.setTag(holder);
} else {
v = convertView;
}
bindView(position, v);
return v;
}
private void bindView(int position, View view) {
final Map dataSet = mData.get(position);
if (dataSet == null) {
return;
}
final ViewBinder binder = mViewBinder;
final View[] holder = (View[]) view.getTag();
final String[] from = mFrom;
final int[] to = mTo;
final int count = to.length;
for (int i = 0; i < count; i++) {
final View v = holder[i];
if (v != null) {
final Object data = dataSet.get(from[i]);
//if(data i)
String text = data == null ? "" : data.toString();
if (text == null) {
text = "";
}
boolean bound = false;
if (binder != null) {
bound = binder.setViewValue(v, data, text);
}
if (!bound) {
if (v instanceof Checkable) {
if (data instanceof Boolean) {
((Checkable) v).setChecked((Boolean) data);
} else {
throw new IllegalStateException(v.getClass().getName() +
" should be bound to a Boolean, not a " + data.getClass());
}
} else if (v instanceof TextView) {
// Note: keep the instanceof TextView check at the bottom of these
// ifs since a lot of views are TextViews (e.g. CheckBoxes).
setViewText((TextView) v, text);
} else if (v instanceof ImageView) {
if (data instanceof Integer) {
setViewImage((ImageView) v, (Integer) data);
} else if(data instanceof Bitmap) {
setViewImage((ImageView) v, (Bitmap)data);
}
} else {
throw new IllegalStateException(v.getClass().getName() + " is not a " +
" view that can be bounds by this SimpleAdapter");
}
}
}
}
}
public void setViewImage(ImageView v, int value) {
v.setImageResource(value);
}
public void setViewImage(ImageView v, Bitmap bm) {
((ImageView) v).setImageBitmap(bm);
}
};
