以下是我的代码。我通过JSONArray获取图像的URL。然后我将图像转换为位图图像并存储在Hashtable中。
我正在使用ImageView在listview中显示图像。所以我使用简单的适配器来获取图像。但图像没有加载。
请帮我解决这个问题，我是Android新手!!!!!!
ArrayList<Hashtable<String, Bitmap>> mylist1 = new ArrayList<Hashtable<String, Bitmap>>();
try{
JSONArray earthquakes = json.getJSONArray("earthquakes");
for(int i=0;i<10;i++){
imagemap = new Hashtable<String, Bitmap>();
JSONObject e = earthquakes.getJSONObject(i);
try
{
aURL = new URL(photo);
}
catch (MalformedURLException e1)
{
// TODO Auto-generated catch block
e1.printStackTrace();
}
URLConnection conn = null;
try
{
conn = aURL.openConnection();
}
catch (IOException e1)
{
// TODO Auto-generated catch block
e1.printStackTrace();
}
try
{
conn.connect();
}
catch (IOException e1)
{
// TODO Auto-generated catch block
e1.printStackTrace();
}
InputStream is = null;
try
{
is = conn.getInputStream();
}
catch (IOException e1)
{
// TODO Auto-generated catch block
e1.printStackTrace();
}
BufferedInputStream bis = new
BufferedInputStream(is,8*1024);
Bitmap bm = BitmapFactory.decodeStream(bis);
imagemap.put("im",bm);
mylist1.add(imagemap);
ListAdapter adapter = new SimpleAdapter(this,mylist1,R.layout.main,new String[] {"im"},new int[] {R.id.image});
setListAdapter(adapter);
下面是我用来将字符串加载到listview中的文本字段的ArrayAdapter。 我有一个ImageView。如何覆盖listadapter以将动态图像加载到listview中。
ListAdapter adapter = new SimpleAdapter(this, mylist , R.layout.main4,
new String[] { "percent","propertyid", "cityname", "statecode", "propertytype", "footage", "bathroom", "bedroom", "price", "estimated" },
new int[] { R.id.percent, R.id.property_id, R.id.city_name, R.id.state_code, R.id.prop_type, R.id.foot, R.id.bath, R.id.bed, R.id.list, R.id.estimat});
setListAdapter(adapter);
答案 0 :(得分：2)
基本上，简单适配器会自动将一些资源ID或URI绑定到行布局的imageview。 但它不支持Bitmap。
这是一个问题，因为每个必须管理位图的人都知道我们经常需要减小图片的大小以防止outOfMemory异常。 但是，如果要将图像添加到listView中，如果仅提供URI，则无法缩小图像的大小。所以这是解决方案：
我修改了simpleAdapter以便能够处理位图。 将此类添加到项目中，并使用它而不是simpleAdapter。 然后，不是传递图像的URI或ressourceId，而是传递Bitmap！
下面是代码：
import java.util.HashMap;
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 ExtendedSimpleAdapter extends SimpleAdapter{
List<? extends Map<String, ?>> map; // if fails to compile, replace with List<HashMap<String, Object>> map
String[] from;
int layout;
int[] to;
Context context;
LayoutInflater mInflater;
public ExtendedSimpleAdapter(Context context, List<? extends Map<String, ?>> data, // if fails to compile, do the same replacement as above on this line
int resource, String[] from, int[] to) {
super(context, data, resource, from, to);
layout = resource;
map = data;
this.from = from;
this.to = to;
this.context = context;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
mInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
return this.createViewFromResource(position, convertView, parent, layout);
}
private View createViewFromResource(int position, View convertView,
ViewGroup parent, int resource) {
View v;
if (convertView == null) {
v = mInflater.inflate(resource, parent, false);
} else {
v = convertView;
}
this.bindView(position, v);
return v;
}
private void bindView(int position, View view) {
final Map dataSet = map.get(position);
if (dataSet == null) {
return;
}
final ViewBinder binder = super.getViewBinder();
final int count = to.length;
for (int i = 0; i < count; i++) {
final View v = view.findViewById(to[i]);
if (v != null) {
final Object data = dataSet.get(from[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 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 {
throw new IllegalStateException(v.getClass().getName() +
" should be bound to a Boolean, not a " +
(data == null ? "<unknown type>" : 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 {
setViewImage((ImageView) v, text);
}
} else {
throw new IllegalStateException(v.getClass().getName() + " is not a " +
" view that can be bounds by this SimpleAdapter");
}
}
}
}
}
private void setViewImage(ImageView v, Bitmap bmp){
v.setImageBitmap(bmp);
}
}
此类的行为与原始类（SimpleAdapter）
完全相同答案 1 :(得分：0)
这就是我在listview中放置图像的方式
public View getView(int position, View convertView, ViewGroup parent) {
View vi=convertView;
ViewHolder holder;
if(convertView==null){
vi = inflater.inflate(R.layout.highscore_item, null);
holder=new ViewHolder();
holder.Icon=(ImageView)vi.findViewById(R.id.icon);
vi.setTag(holder);
}
else
holder=(ViewHolder)vi.getTag();
holder.Icon.setTag(mData[position].getIcon());
imageLoader.DisplayImage(mData[position].getIcon(), activity, holder.Icon);
return vi;
}
如果您想了解更多信息，请查看Lazylist。