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());

         }
 }