png是一种背景透明格式的图片，大量用于网络上，保真性很好，JPG是压缩图片,占用空间少。但有一些失真，所以在将png图片转换成jpg图片之后，肯定是有一些差异的，毕竟这是两种不同的格式.
下面用一个例子将一个透明的png转换成背景为白色的jpg图片import java.awt.Color;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
public class ConvertImageFile {
public static void main(String[] args) {
BufferedImage bufferedImage;
try {
//read image file
bufferedImage = ImageIO.read(new File("c:\\java.png"));
// create a blank, RGB, same width and height, and a white background
BufferedImage newBufferedImage = new BufferedImage(bufferedImage.getWidth(),
bufferedImage.getHeight(), BufferedImage.TYPE_INT_RGB);
newBufferedImage.createGraphics().drawImage(bufferedImage, 0, 0, Color.WHITE, null);
// write to jpeg file
ImageIO.write(newBufferedImage, "jpg", new File("c:\\java.jpg"));
System.out.println("Done");
} catch (IOException e) {
e.printStackTrace();
}
}
}
