如何改变Jpg图像的大小
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如何改变Jpg图像的大小
/**运行方法：
*java ImageSizer 你的输入文件.jpg 你的输出文件.jpg 200 0.5
*/
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.*;
// com.sun.image.codec.jpeg package is included in sun and ibm sdk 1.3
import com.sun.image.codec.jpeg.*;
/**
* Use this class to size images.
*
* @author Dan Becker
*/
public class ImageSizer {
public static final MediaTracker tracker = new MediaTracker( new Component() {} );
/** Adjusts the size of the image to the given coordinates.
* If width or height is -1, the image aspect ration is maintained.
*/
public static Image setSize( Image image, int width, int height ) {
return setSize( image, width, height, java.awt.Image.SCALE_DEFAULT );
} // setSize
/** Adjusts the size of the image to the given coordinates.
* If width or height is -1, the image aspect ration is maintained.
* <p>
* Hints are one of SCALE_DEFAULT, SCALE_FAST, SCALE_SMOOTH,
* SCALE_REPLICATE, SCALE_AREA_AVERAGING as defined in java.awt.Image.
*/
public static Image setSize( Image image, int width, int height, int hints ) {
return image.getScaledInstance( width, height, hints );
} // setSize
/** Checks the given image for valid width and height. */
public static void checkImage( Image image ) {
waitForImage( image );
int imageWidth = image.getWidth( null );
if ( imageWidth < 1 )
throw new IllegalArgumentException( "image width " + imageWidth + " is out of range" );
int imageHeight = image.getHeight( null );
if ( imageHeight < 1 )
throw new IllegalArgumentException( "image height " + imageHeight + " is out of range" );
// System.out.println( "Image size=" + imageWidth + "x" + imageHeight );
} // checkImage
/** Waits for given image to load. Use before querying image height/width/colors. */
public static void waitForImage( Image image ) {
try {
tracker.addImage( image, 0 );
tracker.waitForID( 0 );
// loadStatus = tracker.statusID( 0, false );
tracker.removeImage(image, 0);
} catch( InterruptedException e ) { e.printStackTrace(); }
} // waitForImage
/** Encodes the given image at the given quality to the output stream. */
public static void encodeJPEG( OutputStream outputStream, Image outputImage, float outputQuality )
throws java.io.IOException {
int outputWidth = outputImage.getWidth( null );
if ( outputWidth < 1 )
throw new IllegalArgumentException( "output image width " + outputWidth + " is out of range" );
int outputHeight = outputImage.getHeight( null );
if ( outputHeight < 1 )
throw new IllegalArgumentException( "output image height " + outputHeight + " is out of range" );
// Get a buffered image from the image.
BufferedImage bi = new BufferedImage( outputWidth, outputHeight,
BufferedImage.TYPE_INT_RGB );
Graphics2D biContext = bi.createGraphics();
biContext.drawImage( outputImage, 0, 0, null );
// Note that additional drawing such as watermarks or logos can be placed here.
// com.sun.image.codec.jpeg package is included in sun and ibm sdk 1.3
JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder( outputStream );
// The default quality is 0.75.
JPEGEncodeParam jep = JPEGCodec.getDefaultJPEGEncodeParam( bi );
jep.setQuality( outputQuality, true );
encoder.encode( bi, jep );
// encoder.encode( bi );
outputStream.flush();
} // encodeImage
/** Test program */
public static void main( String [] args )
throws java.io.IOException {
if (args.length < 4) {
System.out.println( "ImageSizer - changes the size of an image." );
System.out.println( "use: java ImageSizer inputFile outputFile outputWidth outputQuality" );
return;
}
// Gather input arguments.
String inputFileName = args[ 0 ];
String outputFileName = args[ 1 ];
int outputWidth = Integer.parseInt( args[ 2 ] );
if ( outputWidth < 1 )
throw new IllegalArgumentException( "output width \"" + args[ 2 ] +"\" out of range" );
float outputQuality = Float.parseFloat( args[ 3 ] );
if (( outputQuality < 0.0F ) || ( outputQuality > 1.0F ))
throw new IllegalArgumentException( "output quality \"" + args[ 3 ] +"\" out of range" );
// Get input image
Image inputImage = Toolkit.getDefaultToolkit().getImage( inputFileName );
checkImage( inputImage );
// System.out.println( "Input image size=" + inputImage.getWidth( null ) + "x" + inputImage.getHeight( null ) );
// Create output image.
Image outputImage = ImageSizer.setSize( inputImage, outputWidth, -1 );
checkImage( outputImage );
// System.out.println( "Output image size=" + outputImage.getWidth( null ) + "x" + outputImage.getHeight( null ) );
// Encode JPEG file.
FileOutputStream fos = new FileOutputStream( outputFileName );
encodeJPEG( fos, outputImage, outputQuality );
fos.close();
// For some reason, the MediaTracker/ImageProducer likes to hang on.
System.exit( 0 );
} // main
} // class ImageSizer |
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