How to read a image url in google appengine using java

问题

The ImageIO is not in the whitelist of GAE. How to read a image(JPG,PNG) from url as ImageBuffer without using ImageIO?

回答1:

You could read the url stream and create a bytearray using the IOUtils from apache commons.

URL url = new URL(this.url);
InputStream input = url.openStream();
byteArray = IOUtils.toByteArray(input)

^{Note:
toByteArray method buffers the input internally, so there is no need to use a BufferedInputStream.}

EDIT:
BufferedImage is listed as not supported on AppEngine; that means that you CAN'T use that third party library on Google App Engine.

回答2:

just use this Google App Engine built in API

byte[] b = URLFetchServiceFactory.getURLFetchService().fetch( url ).getContent();

No third party library required !!!

回答3:

If you need to read the image content, not only its byte stream, the library https://github.com/pascalleclercq/appengine-awt does the job very well, just replace the usual imports with:

import com.google.code.appengine.awt.image.BufferedImage
import com.google.code.appengine.imageio.ImageIO

The library is published at Maven at https://mvnrepository.com/artifact/fr.opensagres.xdocreport.appengine-awt/appengine-awt/1.0.0

来源：https://stackoverflow.com/questions/6856552/how-to-read-a-image-url-in-google-appengine-using-java