Question

我试图从图像路径中获取位图图像。但BitmapFactory.decodeStream会返回null值。

代码：

URL url = new URL(path);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setDoInput(true);
connection.connect();
InputStream input = connection.getInputStream();
Bitmap myBitmap = BitmapFactory.decodeStream(input);
connection.disconnect();
input.close();

我在更多网站上搜索过，但仍然没有得到解决方案。

Answer 1

获得解决方案：

HttpGet httpRequest = new HttpGet(URI.create(path) );
HttpClient httpclient = new DefaultHttpClient();
HttpResponse response = (HttpResponse) httpclient.execute(httpRequest);
HttpEntity entity = response.getEntity();
BufferedHttpEntity bufHttpEntity = new BufferedHttpEntity(entity);
bmp = BitmapFactory.decodeStream(bufHttpEntity.getContent());
httpRequest.abort();

问题是，一旦您使用InputStream中的HttpUrlConnection，就无法再次回放并再次使用相同的InputStream。因此，您必须为图像的实际采样创建新的InputStream。否则，我们必须中止HTTP请求。

Answer 2

public Bitmap getBitmapFromUrl(String url)
{
Bitmap bm = null;
InputStream is = null;
BufferedInputStream bis = null;
try 
{
    URLConnection conn = new URL(url).openConnection();
    conn.connect();
    is = conn.getInputStream();
    bis = new BufferedInputStream(is, 8192);
    bm = BitmapFactory.decodeStream(bis);
}
catch (Exception e) 
{
    e.printStackTrace();
}
finally {
    if (bis != null) 
    {
        try 
        {
            bis.close();
        }
        catch (IOException e) 
        {
            e.printStackTrace();
        }
    }
    if (is != null) 
    {
        try 
        {
            is.close();
        }
        catch (IOException e) 
        {
            e.printStackTrace();
        }
    }
}
return bm;
}

别忘了在一个帖子（不是主线程）中调用它

Answer 3

使用以下代码，我可以从网址

下载图片

String IMAGE_URL = "http://www.kolkatabirds.com/rainquail8vt.jpg";
            //where we want to download it from
            URL url;
            try {
                url = new URL(IMAGE_URL);

                //open the connection
                URLConnection ucon = url.openConnection();

                //buffer the download
                InputStream is = ucon.getInputStream();
                BufferedInputStream bis = new BufferedInputStream(is,1024);

                //get the bytes one by one
                int current = 0;

                while ((current = bis.read()) != -1) {
                    baf.append((byte) current);
                }
                //convert it back to an image
                ByteArrayInputStream imageStream = new ByteArrayInputStream(baf.toByteArray());
                Bitmap theImage = BitmapFactory.decodeStream(imageStream);
                img.setImageBitmap(theImage);

Answer 4

在decodestream之前需要BufferedInputStream ....

试试这个，它非常适合我使用;

BufferedInputStream buf = new BufferedInputStream(inputsteam, 1024);

传递buf解码流，它将完美地工作。

Bitmap theImage = BitmapFactory.decodeStream(buf);

最后设置你的位图。

Answer 5

我有同样的问题但在我的情况下问题是资源（图像）。由于Android不支持CMYK图像，因此请确保图像不是CMYK颜色模式。有关详细信息，请参阅this question

祝你好运;）

Android：bitmapfactory.decodestream返回null

5 个答案: