java如何生成imagecode

java如何生成imagecode？？？？？

package image;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.Random;

import javax.imageio.ImageIO;

public class ImageCode {

	public static void main(String[] args) throws IOException {
		generateImageCode();
	}
	
	public static void generateImageCode() throws IOException {
		System.out.println("generating image code...");
		
		int height = 22;
		int width = 68;
		// 1.创建图片缓存区
		BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
		
		// 2.创建绘制环境
		Graphics paint = image.getGraphics();
		Color c = new Color(200, 150, 255);
		// 设置画笔
		paint.setColor(c);
		// 画背景
		paint.fillRect(0, 0, width, height);
		
		// 绘制数字和字母
		StringBuffer codes = new StringBuffer();
		char[] ch = "QWERTYUIOPASDFGHJKLZXCVBNM1234567890".toCharArray();
		Random r = new Random();
		int index;
		
		for(int i = 0; i < 4; i++) {
			index = r.nextInt(ch.length);
			// 设置文本颜色
			paint.setColor(new Color(r.nextInt(88), r.nextInt(150), r.nextInt(255)));
			paint.drawString(ch[index]+"", (i*16)+3, 18);
			codes.append(ch[index]);
		}
		
		File file = new File("./out.jpg");
		ImageIO.write(image, "JPG", file);
		
		System.out.println("generate image code successfully");
	}

}