java如何在从web下载图像时保持原始图像的dpi？

Question

我用Java编写了一个短程序，从url下载图像。它工作正常，只是dpi从300dpi自动降低到90dpi

有没有办法保持原始图像的dpi？代码如下：

import java.net.*;
import java.io.*;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.awt.image.RenderedImage;

import javax.imageio.ImageIO;

public class downloader1 {
    public static void main(String[] args) throws Exception {

        //Open URL//
        URL url = new URL("url.jpg");

        //Save Image.//
        Image image = null;
        image = ImageIO.read(url);

        try {
            ImageIO.write((RenderedImage) image, "jpg", new File("image4.jpg"));
            } catch (IOException ex) {
        }

    }


}