How to view an image from blob column in Oracle wi

问题:

I tried defining an image element in the report layout and setting type to java.io.Inputstream but that doesn't work, also I tried setting to java.awt.Image and neither works, the exception that I'm getting is

java.lang.ClassCastException: oracle.sql.BLOB cannot be cast to java.awt.Image

or

java.lang.ClassCastException: oracle.sql.BLOB cannot be cast to java.io.InputStream

Also I tried to google but the results are that what I'm doing right now.

Thanks for your help.

回答1:

Without seeing how you're calling the blob to embed the image within your report code...

1. Use blob.getBinaryStream().
2. Convert the stream using javax.imageio.ImageIO.read( InputStream ).

For example:

javax.imageio.ImageIO.read( blob.getBinaryStream() )

This will return an instance of BufferedImage, which subclasses java.awt.Image, and should be a suitable object to embed in the report.

The blob variable shown in the example will have to use the appropriate variable from the report (that represents the data from the desired column).

See also:

• https://forums.oracle.com/forums/thread.jspa?threadID=2081381

回答2:

InputStream is = new ByteArrayInputStream((byte[]) yourBlobData);
myImage = new DefaultStreamedContent(is, "image/png");

in jsf page;

<p:graphicImage value="#{controller.myImage}" style="width:200px;width:500px" />