如何在ImageView中使用URL引用的图像?
当前回答
要做到这一点,一个简单而干净的方法是使用开源库Prime。
其他回答
适用于任何容器中的imageView,比如listview grid view, normal layout
private class LoadImagefromUrl extends AsyncTask< Object, Void, Bitmap > {
ImageView ivPreview = null;
@Override
protected Bitmap doInBackground( Object... params ) {
this.ivPreview = (ImageView) params[0];
String url = (String) params[1];
System.out.println(url);
return loadBitmap( url );
}
@Override
protected void onPostExecute( Bitmap result ) {
super.onPostExecute( result );
ivPreview.setImageBitmap( result );
}
}
public Bitmap loadBitmap( String url ) {
URL newurl = null;
Bitmap bitmap = null;
try {
newurl = new URL( url );
bitmap = BitmapFactory.decodeStream( newurl.openConnection( ).getInputStream( ) );
} catch ( MalformedURLException e ) {
e.printStackTrace( );
} catch ( IOException e ) {
e.printStackTrace( );
}
return bitmap;
}
/** Usage **/
new LoadImagefromUrl( ).execute( imageView, url );
你必须先下载图像
public static Bitmap loadBitmap(String url) {
Bitmap bitmap = null;
InputStream in = null;
BufferedOutputStream out = null;
try {
in = new BufferedInputStream(new URL(url).openStream(), IO_BUFFER_SIZE);
final ByteArrayOutputStream dataStream = new ByteArrayOutputStream();
out = new BufferedOutputStream(dataStream, IO_BUFFER_SIZE);
copy(in, out);
out.flush();
final byte[] data = dataStream.toByteArray();
BitmapFactory.Options options = new BitmapFactory.Options();
//options.inSampleSize = 1;
bitmap = BitmapFactory.decodeByteArray(data, 0, data.length,options);
} catch (IOException e) {
Log.e(TAG, "Could not load Bitmap from: " + url);
} finally {
closeStream(in);
closeStream(out);
}
return bitmap;
}
然后使用Imageview。setImageBitmap将位图设置为ImageView
你也可以使用LoadingImageView视图从url加载图片:
http://blog.blundellapps.com/imageview-with-loading-spinner/
一旦你从链接中添加了类文件,你就可以实例化一个url图像视图:
在xml:
<com.blundell.tut.LoaderImageView
android:id="@+id/loaderImageView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
image="http://developer.android.com/images/dialog_buttons.png"
/>
在代码:
final LoaderImageView image = new LoaderImageView(this, "http://developer.android.com/images/dialog_buttons.png");
并更新它使用:
image.setImageDrawable("http://java.sogeti.nl/JavaBlog/wp-content/uploads/2009/04/android_icon_256.png");
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;
}
}
我写了一个类来处理这个问题,因为它似乎是我各种项目中反复出现的需求:
https://github.com/koush/UrlImageViewHelper
UrlImageViewHelper will fill an ImageView with an image that is found at a URL. The sample will do a Google Image Search and load/show the results asynchronously. UrlImageViewHelper will automatically download, save, and cache all the image urls the BitmapDrawables. Duplicate urls will not be loaded into memory twice. Bitmap memory is managed by using a weak reference hash table, so as soon as the image is no longer used by you, it will be garbage collected automatically.
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