Android的：如何使用异步下载一个PNG文件并将其设置为ImageView的？

问题描述

我有一个的PNG图片，需要下载并设置为ImageView的源的URL。我是个初学者，到目前为止，所以有一些事情我不明白：1）我在哪里存储文件？2）如何设置它在Java code ImageView的？3）如何正确地重写AsyncTask的方法？

I've got the URL of a .png image, that needs to be downloaded and set as a source of an ImageView. I'm a beginner so far, so there are a few things I don't understand:1) Where do I store the file?2) How do I set it to the ImageView in java code?3) How to correctly override the AsyncTask methods?

在此先感谢，将高度AP preciate任何形式的帮助。

Thanks in advance, will highly appreciate any kind of help.

推荐答案

我不知道，你可以明确地从下载建立一个PNG。然而，这里是我用它来下载图片，并显示他们到Imageviews：

I'm not sure you can explicity build a png from a download. However, here is what I use to download images and display them into Imageviews :

首先，你下载的图片：

protected static byte[] imageByter(Context ctx, String strurl) {
    try {
        URL url = new URL(urlContactIcon + strurl);
        InputStream is = (InputStream) url.getContent();
        byte[] buffer = new byte[8192];
        int bytesRead;
        ByteArrayOutputStream output = new ByteArrayOutputStream();
        while ((bytesRead = is.read(buffer)) != -1) {
            output.write(buffer, 0, bytesRead);
        }
        return output.toByteArray();
    } catch (MalformedURLException e) {
        e.printStackTrace();
    return null;
    } catch (IOException e) {
        e.printStackTrace();
        return null;
    }
}

然后，创建一个位图和它关联到ImageView的：

And then, create a BitMap and associate it to the Imageview :

bytes = imagebyter(this, mUrl);
bm = BitmapFactory.decodeByteArray(bytes, 0, bytes.length);
yourImageview.setImageBitmap(bm);

这就是它。

修改
其实，你可以通过这样保存文件：

EDIT
Actually, you can save the file by doing this :

File file = new File(fileName);
FileOutputStream fos = new FileOutputStream(file);
fos.write(imagebyter(this, mUrl));
fos.close();

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