如何从哈希表获取位图图像到简单的适配器中以在listactivity的imageview中查看

Question

下面是我的代码。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哈希表中。

我正在使用 ImageView 在列表视图中显示图像。所以我使用简单的适配器来获取图像。但图像未加载。

请帮助我解决这个问题，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);

更新：

下面是我用来将字符串加载到列表视图中的文本字段的ArrayAdapter。 我里面有一个 ImageView 。如何重写 listadapter 将动态图像加载到列表视图中。

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);

Answer 1

基本上，简单的适配器会自动将一些资源 ID 或 URI 绑定到行布局的图像视图。
但它不支持位图。

这是一个问题，因为每个必须管理位图的人都知道，我们经常必须减小图片的大小以防止内存不足异常。
但是，如果您想将图像添加到 listView 中，如果仅提供 URI，则无法减小图像的大小。所以这是解决方案：

我修改了 simpleAdapter 以能够处理位图。
将此类添加到您的项目中，并使用它而不是 simpleAdapter。
然后，不要传递图像的 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);
}



}

这个类的行为与原始类（SimpleAdapter）完全相同

Answer 2

这就是我将图像放入列表视图中的方法

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;
}

看看 Lazylist 如果您想了解更多信息。