java graphics 实例化_Java Graphics - 如何创建BufferedImage并绘制自己

import java.awt.Color;

import java.awt.Dimension;

import java.awt.EventQueue;

import java.awt.Graphics2D;

import java.awt.GridLayout;

import java.awt.image.BufferedImage;

import javax.swing.ImageIcon;

import javax.swing.JFrame;

import javax.swing.JLabel;

import javax.swing.JPanel;

public class Main {

public static void main(String[] args) {

EventQueue.invokeLater(new Runnable() {

@Override

public void run() {

JFrame f = new JFrame();

f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

f.add(new MyPanel());

f.pack();

f.setVisible(true);

}

});

}

}

class MyPanel extends JPanel {

int W = 800;

int H = 600;

public MyPanel() {

this.setLayout(new GridLayout());

this.setPreferredSize(new Dimension(W, H));

int w = W / 2;

int h = H / 2;

int r = w / 5;

BufferedImage bi = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);

Graphics2D g = bi.createGraphics();

g.setColor(Color.gray);

g.fillRect(0, 0, w, h);

g.setColor(Color.blue);

g.fillRect(w / 2 - r, h / 2 - r / 2, 2 * r, r);

g.dispose();

this.add(new JLabel(new ImageIcon(bi), JLabel.CENTER));

}

}