如何在Android中通过URL加载ImageView？

Question

你如何使用URL引用的图像ImageView？

Answer 1

来自Android开发者:

// 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);
    }
}

确保您在AndroidManifest.xml访问互联网时设置了以下权限.

<uses-permission android:name="android.permission.INTERNET" />

Answer 2

1. 毕加索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. Glide Android的图像加载和缓存库专注于平滑滚动

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,用于在Android应用程序中显示图像.Fresco负责图像加载和显示,因此您不必这样做.

Fresco入门

Answer 3

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

Answer 4

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将使用在URL处找到的图像填充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.重复的网址不会被加载到内存中两次.位图内存通过使用弱引用哈希表进行管理,因此只要您不再使用该图像,就会自动对其进行垃圾回收.

Answer 5

无论如何,人们要求我的评论将其作为答案发布.我发布了.

URL newurl = new URL(photo_url_str); 
mIcon_val = BitmapFactory.decodeStream(newurl.openConnection().getInputStream());
profile_photo.setImageBitmap(mIcon_val);

谢谢.

Answer 6

如果您基于按钮单击加载图像,则上面接受的答案很好,但是如果您在新活动中执行此操作,则会将UI冻结一两秒钟.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);
    }    
}

并使用以下命令从onCreate()方法调用:

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

结果是快速加载的活动和图像视图,根据用户的网络速度显示一瞬间.

Answer 7

您还可以使用此LoadingImageView视图从URL加载图像:

http://blog.blundellapps.com/imageview-with-loading-spinner/

从该链接添加类文件后,您可以实例化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");

并使用以下方式更新它

image.setImageDrawable("http://java.sogeti.nl/JavaBlog/wp-content/uploads/2009/04/android_icon_256.png");

Answer 8

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;
}
}

Answer 9

嗨,我有最简单的代码试试这个

    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中

  <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"/>

试试这个

Answer 10

我最近在这里找到了一个线程,因为我必须对带有图像的列表视图做类似的事情,但原理很简单,因为你可以在那里显示的第一个示例类中读取(通过jleedev).你得到图像的输入流(来自网络)

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,然后将其传递给ImageView(通过setImageDrawable).再次从上面的代码片段看一下整个线程.

InputStream is = fetch(urlString);
Drawable drawable = Drawable.createFromStream(is, "src");

Answer 11

对我来说,这个任务最好的现代图书馆是Picasso by Square.它允许通过URL使用单行将图像加载到ImageView:

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

Answer 12

这里有很多好消息...我最近发现了一个名为SmartImageView的类,到目前为止看起来效果非常好.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:我最后写了一篇关于此的博客文章,因此请查看有关使用SmartImageView的帮助.

第二次更新:我现在总是使用Picasso(见上文)并强烈推荐它.:)

Answer 13

这是一个迟到的回复,正如上面建议的那样,AsyncTask谷歌搜索后我发现了另一种解决这个问题的方法.

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的访问互联网中添加以下权限.

<uses-permission android:name="android.permission.INTERNET" />

我自己尝试过,我还没有遇到任何问题.

Answer 14

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

Answer 15

这会对你有所帮助......

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;
}