输入流到BufferedImage转换会损坏文件

Question

我正在使用servelt上传一些图像文件.我想调整图像大小.我使用下面的行将源转换为BufferedImage.

InputStream imageStream = item.getInputStream();

BufferedImage imageBuffer = ImageIO.read(imageStream);

然后我调整图像大小并写入一个位置.但是,所有输出文件的大小都是0.

我使用以下代码来调整图像大小.

AffineTransform at = new AffineTransform();
if(sx != 0)
    at.scale( sx , sx );
AffineTransformOp ato = new AffineTransformOp(at, AffineTransformOp.TYPE_BILINEAR);
uploadImage = ato.filter(uploadImage, null); //uploadImage == BufferedImage

有没有什么好方法可以将输入流转换为bufferedImage而不会损坏图像？我确信图片上传了.但是,在转换为BufferedImage之后,该文件已损坏.

我通过向doPost()方法提交表单来上传.下面的行给出了一个列表项的InputStream.

InputStream imageStream = item.getInputStream();

而且,我正在写它

ImageIO.write(image, "jpg", new File(path + ".jpg"));

更新

java.awt.image.ImagingOpException: Unable to transform src image
at java.awt.image.AffineTransformOp.filter(Unknown Source)
at com.pricar.servlet.imageupload.ImageUploadServlet.reSize(ImageUploadServlet.java:100)
at com.pricar.servlet.imageupload.ImageUploadServlet.doPost(ImageUploadServlet.java:74)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:641)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:390)
at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418)
at org.mortbay.jetty.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:230)
at org.mortbay.jetty.handler.HandlerCollection.handle(HandlerCollection.java:114)
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at org.mortbay.jetty.Server.handle(Server.java:326)
at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:943)
at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:756)
at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:218)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:410)
at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:582)

任何suggesstions或链接woulb是赞赏!

谢谢!

Answer 1

您的代码无法正常工作的原因在于

uploadImage = ato.filter(uploadImage, null); //uploadImage == BufferedImage

您的目标图片为null.

您必须创建一个新的BufferedImage来放置缩放版本,如下所示:

BufferedImage dstImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
ato.filter(uploadImage, dstImage);

然后,保存dstImage(使用ImageIO.write).

编辑:

缩小图像的一种更简单的方法是将其绘制到正确大小的dstImage中:

int dstWidth = 100;
int dstHeight = 100;
InputStream imageStream = item.getInputStream();
BufferedImage srcImage = ImageIO.read(imageStream);
if (srcImage == null) { System.err.println("NO SOURCE IMAGE!"); }
BufferedImage dstImage = new BufferedImage(dstWidth, dstHeight,
    BufferedImage.TYPE_INT_RGB);
dstImage.getGraphics().drawImage(
    srcImage, 0, 0, dstWidth, dstHeight, null);
ImageIO.write(dstImage, "jpg", new File(path + ".jpg"));