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<TITLE>Determining the Format of an Image in a File (Java Developers Almanac Example)
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<B><A HREF="../javax.imageio/pkg.html">javax.imageio</A></B><font color="#666666" class="xsmall-font">
[6 examples]
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<h3>e698. Determining the Format of an Image in a File</h3>
The <code>javax.imageio</code> package can determine the type of image in a file or
input stream.
<pre> try {
// Get image format in a file
File file = new File(<font color="#0066ff"><i>"image.gif"</i></font>);
String formatName = getFormatName(file);
// e.g. gif
// Get image format from an input stream
InputStream is = <font color="#0066ff"><i>new FileInputStream(file)</i></font>;
formatName = getFormatName(is);
is.close();
} catch (IOException e) {
}
// Returns the format of the image in the file 'f'.
// Returns null if the format is not known.
public static String getFormatInFile(File f) {
return getFormatName(f);
}
// Returns the format of the image in the input stream 'is'.
// Returns null if the format is not known.
public static String getFormatFromStream(InputStream is) {
return getFormatName(is);
}
// Returns the format name of the image in the object 'o'.
// 'o' can be either a File or InputStream object.
// Returns null if the format is not known.
private static String getFormatName(Object o) {
try {
// Create an image input stream on the image
ImageInputStream iis = ImageIO.createImageInputStream(o);
// Find all image readers that recognize the image format
Iterator iter = ImageIO.getImageReaders(iis);
if (!iter.hasNext()) {
// No readers found
return null;
}
// Use the first reader
ImageReader reader = (ImageReader)iter.next();
// Close stream
iis.close();
// Return the format name
return reader.getFormatName();
} catch (IOException e) {
}
// The image could not be read
return null;
}
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<b>Related Examples</b></font></td>
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e694. <a class="eglink" href="BasicImageRead.html?l=rel">
Reading an Image from a File, InputStream, or URL
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e695. <a class="eglink" href="Graphic2File.html?l=rel">
Saving a Generated Graphic to a PNG or JPEG File
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e696. <a class="eglink" href="GetFormats.html?l=rel">
Listing the Image Formats That Can Be Read and Written
</a>
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e697. <a class="eglink" href="DetermineFormat.html?l=rel">
Determining If an Image Format Can Be Read or Written
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e699. <a class="eglink" href="JpegWrite.html?l=rel">
Compressing a JPEG File
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