java实现修改图片dpi(像素/大小)

import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGEncodeParam;
import com.sun.image.codec.jpeg.JPEGImageEncoder;

import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;

public class DPIHandleHelper {
private static int DPI = 300;

public static void main(String[] args) {
    String path = "C:\\test.jpg";
    File file = new File(path);
    handleDpi(file, 300, 300);
}

/**
 * 改变图片DPI
 *
 * @param file
 * @param xDensity
 * @param yDensity
 */
public static void handleDpi(File file, int xDensity, int yDensity) {
    try {
        BufferedImage image = ImageIO.read(file);
        JPEGImageEncoder jpegEncoder = JPEGCodec.createJPEGEncoder(new FileOutputStream(file));
        JPEGEncodeParam jpegEncodeParam = jpegEncoder.getDefaultJPEGEncodeParam(image);
        jpegEncodeParam.setDensityUnit(JPEGEncodeParam.DENSITY_UNIT_DOTS_INCH);
        jpegEncoder.setJPEGEncodeParam(jpegEncodeParam);
        jpegEncodeParam.setQuality(0.75f, false);
        jpegEncodeParam.setXDensity(xDensity);
        jpegEncodeParam.setYDensity(yDensity);
        jpegEncoder.encode(image, jpegEncodeParam);
        image.flush();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

}