如何使用URL中引用的图像ImageView？
Answers:
来自Android开发人员：
// show The Image in a ImageView
new DownloadImageTask((ImageView) findViewById(R.id.imageView1))
.execute("http://java.sogeti.nl/JavaBlog/wp-content/uploads/2009/04/android_icon_256.png");
public void onClick(View v) {
startActivity(new Intent(this, IndexActivity.class));
finish();
}
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);
}
}确保您已设置以下AndroidManifest.xml访问互联网的权限。
<uses-permission android:name="android.permission.INTERNET" />1. Picasso允许在您的应用程序中轻松加载图像-通常只需一行代码！
使用Gradle：
implementation 'com.squareup.picasso:picasso:2.71828'只需一行代码！
Picasso.get().load("http://i.imgur.com/DvpvklR.png").into(imageView);2. 滑行 Android的图像加载和缓存库着重于平滑滚动
使用Gradle：
repositories {
mavenCentral()
google()
}
dependencies {
implementation 'com.github.bumptech.glide:glide:4.7.1'
annotationProcessor 'com.github.bumptech.glide:compiler:4.7.1'
}//对于一个简单的视图：
Glide.with(this).load("http://i.imgur.com/DvpvklR.png").into(imageView);3. fresco 是一个功能强大的系统，可在Android应用程序中显示图像。Fresco负责图像的加载和显示，因此您不必这样做。
您必须先下载图像
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
我编写了一个类来处理此问题，因为在我的各个项目中似乎都反复出现这种需求：
https://github.com/koush/UrlImageViewHelper
UrlImageViewHelper将使用URL中找到的图像填充ImageView。
该示例将执行Google图片搜索并异步加载/显示结果。
UrlImageViewHelper将自动下载，保存和缓存BitmapDrawables的所有图像URL。重复的网址不会两次加载到内存中。位图内存是通过使用弱引用哈希表来管理的，因此一旦您不再使用该图像，就会自动对其进行垃圾回收。
无论如何，人们要求我发表评论以作为答案。我正在发布。
URL newurl = new URL(photo_url_str);
mIcon_val = BitmapFactory.decodeStream(newurl.openConnection().getInputStream());
profile_photo.setImageBitmap(mIcon_val);如果您是通过单击按钮加载图像的，则上面接受的答案很好，但是，如果您在新活动中进行图像加载，则会冻结UI一两秒钟。环顾四周，我发现一个简单的asynctask消除了这个问题。
要使用asynctask，请在活动结束时添加此类：
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);
}
}并使用以下方法从onCreate（）方法进行调用：
new DownloadImageTask((ImageView) findViewById(R.id.imageView1))
.execute(MY_URL_STRING);结果是快速加载的活动和一个图像视图，稍后根据用户的网络速度显示一秒钟。
您还可以使用此LoadingImageView视图从url加载图像：
http://blog.blundellapps.com/imageview-with-loading-spinner/
一旦从该链接添加了类文件，就可以实例化url图像视图：
在xml中：
<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"
/>在代码中：
final LoaderImageView image = new LoaderImageView(this, "http://developer.android.com/images/dialog_buttons.png");并使用以下命令更新它：
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;
}
}嗨，我有最简单的代码，试试看
public class ImageFromUrlExample extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
ImageView imgView =(ImageView)findViewById(R.id.ImageView01);
Drawable drawable = LoadImageFromWebOperations("http://www.androidpeople.com/wp-content/uploads/2010/03/android.png");
imgView.setImageDrawable(drawable);
}
private Drawable LoadImageFromWebOperations(String url)
{
try{
InputStream is = (InputStream) new URL(url).getContent();
Drawable d = Drawable.createFromStream(is, "src name");
return d;
}catch (Exception e) {
System.out.println("Exc="+e);
return null;
}
}
}main.xml
<LinearLayout
android:id="@+id/LinearLayout01"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
xmlns:android="http://schemas.android.com/apk/res/android">
<ImageView
android:id="@+id/ImageView01"
android:layout_height="wrap_content"
android:layout_width="wrap_content"/>尝试这个
我最近在这里找到了一个线程，因为我必须对带有图像的listview做类似的事情，但是原理很简单，因为您可以在其中显示的第一个示例类中阅读（由jleedev编写）。您可以从网络获取图像的输入流
private InputStream fetch(String urlString) throws MalformedURLException, IOException {
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpGet request = new HttpGet(urlString);
HttpResponse response = httpClient.execute(request);
return response.getEntity().getContent();
}然后，将图像存储为Drawable，并将其传递给ImageView（通过setImageDrawable）。再次从上面的代码片段中查看整个线程。
InputStream is = fetch(urlString);
Drawable drawable = Drawable.createFromStream(is, "src");这里有很多很好的信息...我最近发现了一个名为SmartImageView的类，到目前为止似乎工作得很好。非常容易合并和使用。
http://loopj.com/android-smart-image-view/
https://github.com/loopj/android-smart-image-view
更新：我最终写了一篇有关此的博客文章，因此请查看有关使用SmartImageView的帮助。
第二次更新：我现在总是为此使用Picasso（请参见上文），并强烈推荐它。:)
这是一个较晚的答复，正如上面所建议的那样AsyncTask，在谷歌搜索了一下之后，我发现了解决此问题的另一种方法。
Drawable drawable = Drawable.createFromStream((InputStream) new URL("url").getContent(), "src");
imageView.setImageDrawable(drawable);
这是完整的功能：
public void loadMapPreview () {
//start a background thread for networking
new Thread(new Runnable() {
public void run(){
try {
//download the drawable
final Drawable drawable = Drawable.createFromStream((InputStream) new URL("url").getContent(), "src");
//edit the view in the UI thread
imageView.post(new Runnable() {
public void run() {
imageView.setImageDrawable(drawable);
}
});
} catch (IOException e) {
e.printStackTrace();
}
}
}).start();
}不要忘记在您AndroidManifest.xml的互联网中添加以下权限。
<uses-permission android:name="android.permission.INTERNET" />
我自己尝试过，还没有遇到任何问题。
Thread由于UI线程不允许进行网络操作，因此需要额外运行。
这将帮助您...
定义imageview并将图像加载到其中。
Imageview i = (ImageView) vv.findViewById(R.id.img_country);
i.setImageBitmap(DownloadFullFromUrl(url));然后定义此方法：
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;
} String img_url= //url of the image
URL url=new URL(img_url);
Bitmap bmp;
bmp=BitmapFactory.decodeStream(url.openConnection().getInputStream());
ImageView iv=(ImageView)findviewById(R.id.imageview);
iv.setImageBitmap(bmp);具有异常处理和异步任务的版本：
AsyncTask<URL, Void, Boolean> asyncTask = new AsyncTask<URL, Void, Boolean>() {
public Bitmap mIcon_val;
public IOException error;
@Override
protected Boolean doInBackground(URL... params) {
try {
mIcon_val = BitmapFactory.decodeStream(params[0].openConnection().getInputStream());
} catch (IOException e) {
this.error = e;
return false;
}
return true;
}
@Override
protected void onPostExecute(Boolean success) {
super.onPostExecute(success);
if (success) {
image.setImageBitmap(mIcon_val);
} else {
image.setImageBitmap(defaultImage);
}
}
};
try {
URL url = new URL(url);
asyncTask.execute(url);
} catch (MalformedURLException e) {
e.printStackTrace();
} private Bitmap getImageBitmap(String url) {
Bitmap bm = null;
try {
URL aURL = new URL(url);
URLConnection conn = aURL.openConnection();
conn.connect();
InputStream is = conn.getInputStream();
BufferedInputStream bis = new BufferedInputStream(is);
bm = BitmapFactory.decodeStream(bis);
bis.close();
is.close();
} catch (IOException e) {
Log.e(TAG, "Error getting bitmap", e);
}
return bm;
} 在任何容器中使用imageView，例如listview网格视图，常规布局
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 );尝试这种方式，希望这将帮助您解决问题。
在这里，我解释了如何使用“ AndroidQuery”外部库以asyncTask方式从url /服务器加载图像，并且还将加载的图像缓存到设备文件或缓存区域。
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.