Question

下面的Java程序要想实现旋转图片的功能，该怎么修改

import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;

import javax.swing.*;
public class lianxi13 extends JFrame{
JPanel n,jPanel;
JLabel n1;

ImageIcon n3;
JButton n4,n5;
public lianxi13(){
super("fds");
setSize(600,600);
this.setVisible(true);
n=new JPanel();
n.setLayout(new BorderLayout());
n3=new ImageIcon("D://8.jpg");
n1=new JLabel(n3);
jPanel=new JPanel();
n.add(n1,BorderLayout.WEST);
n.add(jPanel,BorderLayout.EAST);
n4=new JButton("缩小");
n5=new JButton("扩大");
jPanel.add(n4,BorderLayout.EAST);
jPanel.add(n5,BorderLayout.WEST);
this.add(n);

n4.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
try {
BufferedImage bi = new BufferedImage((int)(n3.getIconWidth()*0.8),(int)(n3.getIconHeight()*0.8),BufferedImage.TYPE_3BYTE_BGR);
bi.getGraphics().drawImage(n3.getImage(), 0, 0, (int)(n3.getIconWidth()*0.8), (int)(n3.getIconHeight()*0.8),null);
bi.getGraphics().dispose();
n3.setImage(bi);
repaint();
} catch (Exception e1) {
e1.printStackTrace();
}

}
});
n5.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
try {
BufferedImage bi = new BufferedImage((int)(n3.getIconWidth()*1.2),(int)(n3.getIconHeight()*1.2),BufferedImage.TYPE_3BYTE_BGR);
bi.getGraphics().drawImage(n3.getImage(), 0, 0, (int)(n3.getIconWidth()*1.2), (int)(n3.getIconHeight()*1.2),null);
bi.getGraphics().dispose();
n3.setImage(bi);
repaint();
} catch (Exception e1) {
e1.printStackTrace();
}

}
});

}
public static void main(String[] args) {
new lianxi13();

}

}

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Answer 1

Image的getGraphics();返回来信强制转换为Graphics2D
调用Graphics2D的rotate(角度，旋转中心x坐标，y坐标)

Answer 2

百度

BufferedImage rotateImage(final BufferedImage bufferedimage

得到过程，添加按钮、设置事件。。。。。