【转载】如何在ListView中显示Bitmap图像

 

http://hi.baidu.com/android_frank/blog/item/a9ead4fbbfd44bdd0b46e046.html

我在一个小项目中需要用到将SD卡中的图片读出后，压缩，再进行显示。在编程过程中，使用SimpleAdapter适配器时，图片资源的ID均需是程序内的本地资源。在网上找到了两个实现方法，第一个我验证了可以实现，第二个比较繁琐还未验证。

1.实现ViewBinder()接口

一般来说，在用simpleAdapter适配器时，我们所要显示的图片资源都是程序内的本地资源，而且是以资源的ID(Resources ID)形式来表现的。但是有时候我们需要用这个适配器来显示网上的远程图片时，该如何直接显示呢？方法是实现ViewBinder()这个接口，在里面定义数据和视图的匹配关系。实例代码如下：

SimpleAdapter notes =new SimpleAdapter(this, list, R.layout.meinungen_list_row, PARAM, newint[]{ R.id.icon,R.id.name, R.id.content});

notes.setViewBinder(new MyViewBinder());

setListAdapter(notes);

publicclass MyViewBinder implements ViewBinder {

@Override

  publicboolean setViewValue(View view, Object data,String textRepresentation){

    if((view instanceof ImageView)&(data instanceof Bitmap)){

      ImageView iv =(ImageView) view;

      Bitmap bm =(Bitmap) data;

      iv.setImageBitmap(bm);

      returntrue;

    }

    returnfalse;

  }

2.重写SimpleAdapter(http://www.pocketdigi.com/20110303/196.html)

myAdapter listItemAdapter;
listItemAdapter =new myAdapter(this,listItem,R.layout.favlv,newString[]{"ItemImage","ItemTv"},newint[]{R.id.ItemImage,R.id.ItemTv});  
下面是myAdapter的实现方法：

 

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);
 }

};