如何在 Java、Android 中下载 ImageView 的图像？

Question

我需要从我的服务器下载图像并将此图像加载到 imageview 中。所以我有一个问题 - 我可以将图像下载到内存中并将其设置为 ImageView，而不保存在 sdcard/本地存储上吗？或者我必须下载到一些文件存储中？如果可能的话，请给我一个例子。

Answer 1

问了同样的问题，所以你可以搜索，

SAME Question

InputStream in = null;
try
{
    URL url = new URL("URL FOR IMAGE");
    URLConnection urlConn = url.openConnection();
    HttpURLConnection httpConn = (HttpURLConnection) urlConn;
    httpConn.connect();
    in = httpConn.getInputStream();
}
catch (MalformedURLException e)
{
    e.printStackTrace();
}
catch (IOException e)
{
    e.printStackTrace();
}
bmpimg = BitmapFactory.decodeStream(in);
ImageView iv = "MY IMAGEVIEW";
iv.setImageBitmap(bmimg);

Answer 2

这可以帮助你。

Bitmap bmImg;
void downloadFile(String fileUrl){
      URL myFileUrl =null;          
      try {
           myFileUrl= new URL(fileUrl);
      } catch (MalformedURLException e) {
           // TODO Auto-generated catch block
           e.printStackTrace();
      }
      try {
           HttpURLConnection conn= (HttpURLConnection)myFileUrl.openConnection();
           conn.setDoInput(true);
           conn.connect();
           InputStream is = conn.getInputStream();

           bmImg = BitmapFactory.decodeStream(is);
           imView.setImageBitmap(bmImg);
      } catch (IOException e) {
           // TODO Auto-generated catch block
           e.printStackTrace();
      }
 }

来源：http://en.androidwiki.com/wiki/Loading_images_from_a_remote_server

也看到这个

http://ballardhack.wordpress.com/2010/04/05/loading-remote-images-in-a-listview-on-android/

Answer 3

好的，首先将该库实现到应用级别的 gradle 中，以便将图像从 url 加载到图像视图中：

 implementation("com.github.bumptech.glide:glide:4.6.1")
            {
                exclude group: "com.android.support"
            }

现在在您的活动中编写以下代码以加载图像：

Glide.with(this).load("url of your image").thumbnail(Glide.with(this).load(R.drawable.loadingsingleimage)).into(imageView);

现在通过执行以下代码将其下载到您的设备存储中..

 download.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                try {
                    BitmapDrawable drawable = (BitmapDrawable) imageView.getDrawable();
                    Bitmap bitmap = drawable.getBitmap();

                    File filepath = Environment.getExternalStorageDirectory();
                    File dir = new File(filepath.getAbsolutePath() + "/MotivationalQuotes/");
                    dir.mkdir();

                    File file = new File(dir, System.currentTimeMillis() + ".png");
                    try {
                        outputStream = new FileOutputStream(file);
                    } catch (FileNotFoundException e) {
                        Toast.makeText(getApplicationContext(), e.getMessage(), Toast.LENGTH_SHORT).show();

                    }

                    bitmap.compress(Bitmap.CompressFormat.PNG, 100, outputStream);

                    try {
                        outputStream.flush();
                    } catch (IOException e) {
                        Toast.makeText(getApplicationContext(), e.getMessage(), Toast.LENGTH_SHORT).show();
                    }
                    try {
                        outputStream.close();
                    } catch (IOException e) {
                        Toast.makeText(getApplicationContext(), e.getMessage(), Toast.LENGTH_SHORT).show();
                    }
                    Toast.makeText(getApplicationContext(), "Downloaded into MotivationalQuotes.", Toast.LENGTH_SHORT).show();
                }
                catch (Exception e) {
                    Toast.makeText(getApplicationContext(), "Image is not loaded yet...", Toast.LENGTH_SHORT).show();
                }
            }

        });

Answer 4

参见here 示例代码。您可以使用BitmapFactory 来实现您的目标：

HttpURLConnection conn= (HttpURLConnection)myFileUrl.openConnection();
conn.setDoInput(true);
conn.connect();
InputStream is = conn.getInputStream();

bmImg = BitmapFactory.decodeStream(is);
imView.setImageBitmap(bmImg);