java修改图片大小

import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;

import javax.imageio.ImageIO;



public class ChangeSize {
    
    
    public static void main(String[] args) throws Exception {
        //读取图片
        BufferedInputStream in = new BufferedInputStream(new FileInputStream("E:/test.png"));
        //字节流转图片对象
        Image bi =ImageIO.read(in);
        //获取图像的高度，宽度
        int height=bi.getHeight(null);
        int width =bi.getWidth(null);
        //构建图片流
        BufferedImage tag = new BufferedImage(width / 2, height / 2, BufferedImage.TYPE_INT_RGB);
        //绘制改变尺寸后的图
        tag.getGraphics().drawImage(bi, 0, 0,width / 2, height / 2, null);  
        //输出流
        BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream("E:/copy.png"));
        //JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
        //encoder.encode(tag);
        ImageIO.write(tag, "PNG",out);
        in.close();
        out.close();
//转字节流
//ByteArrayOutputStream out = new ByteArrayOutputStream();

//ImageIO.write(tag, "PNG",out);

//InputStream is = new ByteArrayInputStream(out.toByteArray());

        }
}