如果你是在点击按钮的基础上加载图像，上面接受的答案是很棒的，但是如果你是在一个新的活动中做这件事，它会冻结UI一到两秒钟。环顾四周，我发现一个简单的asynctask消除了这个问题。

要使用asynctask，在activity的末尾添加这个类:

private class DownloadImageTask extends AsyncTask<String, Void, Bitmap> {
    ImageView bmImage;

    public DownloadImageTask(ImageView bmImage) {
        this.bmImage = bmImage;
    }

    protected Bitmap doInBackground(String... urls) {
        String urldisplay = urls[0];
        Bitmap mIcon11 = null;
        try {
            InputStream in = new java.net.URL(urldisplay).openStream();
            mIcon11 = BitmapFactory.decodeStream(in);
        } catch (Exception e) {
            Log.e("Error", e.getMessage());
            e.printStackTrace();
        }
        return mIcon11;
    }

    protected void onPostExecute(Bitmap result) {
        bmImage.setImageBitmap(result);
    }    
}

从你的onCreate()方法调用使用:

new DownloadImageTask((ImageView) findViewById(R.id.imageView1))
        .execute(MY_URL_STRING);

结果是一个快速加载的活动和一个稍后根据用户的网络速度显示的imageview。

试试这个方法，希望能帮助你解决问题。

这里我解释了如何使用“AndroidQuery”外部库以asyncTask方式从url/server加载图像，并将加载的图像缓存到设备文件或缓存区。

从这里下载“AndroidQuery”库 复制/粘贴这个jar到项目lib文件夹，并将这个库添加到项目构建路径 现在我展示演示如何使用它。

activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:gravity="center">

        <FrameLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content">

            <ImageView
                android:id="@+id/imageFromUrl"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:adjustViewBounds="true"/>
            <ProgressBar
                android:id="@+id/pbrLoadImage"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center"/>

        </FrameLayout>
    </LinearLayout>

MainActivity.java

public class MainActivity extends Activity {

private AQuery aQuery;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    aQuery = new AQuery(this);
    aQuery.id(R.id.imageFromUrl).progress(R.id.pbrLoadImage).image("http://itechthereforeiam.com/wp-content/uploads/2013/11/android-gone-packing.jpg",true,true);
 }
}

Note : Here I just implemented common method to load image from url/server but you can use various types of method which can be provided by "AndroidQuery"to load your image easily.

public class LoadWebImg extends Activity {

String image_URL=
 "http://java.sogeti.nl/JavaBlog/wp-content/uploads/2009/04/android_icon_256.png";

   /** Called when the activity is first created. */
   @Override
   public void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.main);

       ImageView bmImage = (ImageView)findViewById(R.id.image);
    BitmapFactory.Options bmOptions;
    bmOptions = new BitmapFactory.Options();
    bmOptions.inSampleSize = 1;
    Bitmap bm = LoadImage(image_URL, bmOptions);
    bmImage.setImageBitmap(bm);
   }

   private Bitmap LoadImage(String URL, BitmapFactory.Options options)
   {       
    Bitmap bitmap = null;
    InputStream in = null;       
       try {
           in = OpenHttpConnection(URL);
           bitmap = BitmapFactory.decodeStream(in, null, options);
           in.close();
       } catch (IOException e1) {
       }
       return bitmap;               
   }

private InputStream OpenHttpConnection(String strURL) throws IOException{
 InputStream inputStream = null;
 URL url = new URL(strURL);
 URLConnection conn = url.openConnection();

 try{
  HttpURLConnection httpConn = (HttpURLConnection)conn;
  httpConn.setRequestMethod("GET");
  httpConn.connect();

  if (httpConn.getResponseCode() == HttpURLConnection.HTTP_OK) {
   inputStream = httpConn.getInputStream();
  }
 }
 catch (Exception ex)
 {
 }
 return inputStream;
}
}

这将帮助你……

定义imageview并将图像加载到.....

Imageview i = (ImageView) vv.findViewById(R.id.img_country);
i.setImageBitmap(DownloadFullFromUrl(url));

然后定义这个方法:

    public Bitmap DownloadFullFromUrl(String imageFullURL) {
    Bitmap bm = null;
    try {
        URL url = new URL(imageFullURL);
        URLConnection ucon = url.openConnection();
        InputStream is = ucon.getInputStream();
        BufferedInputStream bis = new BufferedInputStream(is);
        ByteArrayBuffer baf = new ByteArrayBuffer(50);
        int current = 0;
        while ((current = bis.read()) != -1) {
            baf.append((byte) current);
        }
        bm = BitmapFactory.decodeByteArray(baf.toByteArray(), 0,
                baf.toByteArray().length);
    } catch (IOException e) {
        Log.d("ImageManager", "Error: " + e);
    }
    return bm;
}

在我看来，最适合完成这项任务的现代图书馆是毕加索广场图书馆。它允许通过URL加载图像到ImageView，只需一行代码:

Picasso.with(context).load("http://i.imgur.com/DvpvklR.png").into(imageView);

imageView.setImageBitmap(BitmapFactory.decodeStream(imageUrl.openStream()));//try/catch IOException and MalformedURLException outside