1.页面展现
<img id="cerificationCode" src="/front/user/cardCoupon/getCerificationCode" style="margin -left: 62px"			onclick="javascript:this.src='/front/user/cardCoupon/getCerificationCode?'+Math.random()">
<a style="color: #dbb04f; font-size: 0.8em; position: relative; bottom: 8px; margin-left: 5px;"
onclick="javascript:$('#cerificationCode').click();">换一个</a>
注意:onclick="javascript:this.src='/front/user/cardCoupon/getCerificationCode?'+Math.random()"是为了刷新验证码一般都会给个随机数,必须保证每次请求的url不同 ,浏览器才会去服务端获取最新数据,相同的url浏览器优先找自己本地缓存的.

2.控制层

@Controller
@RequestMapping("/front/user/cardCoupon")
public class CardCouponController extends BaseController {

	@RequestMapping("/getCerificationCode")
	public void getCerificationCode(HttpServletRequest request, HttpServletResponse response) {
		try {
			response.setHeader("Pragma", "No-cache");
			response.setHeader("Cache-Control", "no-cache");
			response.setDateHeader("Expires", 0);
			response.setContentType("image/jpeg");

			// 生成随机字串
			String verifyCode = VerifyCodeUtils.generateVerifyCode(4);
			// 存入会话session
			HttpSession session = request.getSession(true);
			// 删除以前的
			session.removeAttribute("cerificationCode");
			session.setAttribute("cerificationCode", verifyCode.toLowerCase());
			// 生成图片
			int w = 100, h = 30;

			VerifyCodeUtils.outputImage(w, h, response.getOutputStream(), verifyCode);
		} catch (IOException e) {
			log.error("获取验证码失败", e);
			e.printStackTrace();
		}
	}
3.生成图片验证码工具类
package com.xinfeng.util;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Arrays;
import java.util.Random;

import javax.imageio.ImageIO;

public class VerifyCodeUtils {
	public static final String VERIFY_CODES = "23456789ABCDEFGHJKLMNPQRSTUVWXYZ";
	private static Random random = new Random();

	/**
	 * 使用系统默认字符源生成验证码
	 * 
	 * @param verifySize
	 *            验证码长度
	 * @return
	 */
	public static String generateVerifyCode(int verifySize) {
		return generateVerifyCode(verifySize, VERIFY_CODES);
	}

	/**
	 * 使用指定源生成验证码
	 * 
	 * @param verifySize
	 *            验证码长度
	 * @param sources
	 *            验证码字符源
	 * @return
	 */
	public static String generateVerifyCode(int verifySize, String sources) {
		if (sources == null || sources.length() == 0) {
			sources = VERIFY_CODES;
		}
		int codesLen = sources.length();
		Random rand = new Random(System.currentTimeMillis());
		StringBuilder verifyCode = new StringBuilder(verifySize);
		for (int i = 0; i < verifySize; i++) {
			verifyCode.append(sources.charAt(rand.nextInt(codesLen)));
		}
		return verifyCode.toString();
	}

	/**
	 * 生成随机验证码文件,并返回验证码值
	 * 
	 * @param w
	 * @param h
	 * @param outputFile
	 * @param verifySize
	 * @return
	 * @throws IOException
	 */
	public static String outputVerifyImage(int w, int h, File outputFile, int verifySize) throws IOException {
		String verifyCode = generateVerifyCode(verifySize);
		outputImage(w, h, outputFile, verifyCode);
		return verifyCode;
	}

	/**
	 * 输出随机验证码图片流,并返回验证码值
	 * 
	 * @param w
	 * @param h
	 * @param os
	 * @param verifySize
	 * @return
	 * @throws IOException
	 */
	public static String outputVerifyImage(int w, int h, OutputStream os, int verifySize) throws IOException {
		String verifyCode = generateVerifyCode(verifySize);
		outputImage(w, h, os, verifyCode);
		return verifyCode;
	}

	/**
	 * 生成指定验证码图像文件
	 * 
	 * @param w
	 * @param h
	 * @param outputFile
	 * @param code
	 * @throws IOException
	 */
	public static void outputImage(int w, int h, File outputFile, String code) throws IOException {
		if (outputFile == null) {
			return;
		}
		File dir = outputFile.getParentFile();
		if (!dir.exists()) {
			dir.mkdirs();
		}
		try {
			outputFile.createNewFile();
			FileOutputStream fos = new FileOutputStream(outputFile);
			outputImage(w, h, fos, code);
			fos.close();
		} catch (IOException e) {
			throw e;
		}
	}

	/**
	 * 输出指定验证码图片流
	 * 
	 * @param w
	 * @param h
	 * @param os
	 * @param code
	 * @throws IOException
	 */
	public static void outputImage(int w, int h, OutputStream os, String code) throws IOException {
		int verifySize = code.length();
		BufferedImage image = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
		Random rand = new Random();
		Graphics2D g2 = image.createGraphics();
		g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
		Color[] colors = new Color[5];
		Color[] colorSpaces = new Color[] { Color.WHITE, Color.CYAN, Color.GRAY, Color.LIGHT_GRAY, Color.MAGENTA,
				Color.ORANGE, Color.PINK, Color.YELLOW };
		float[] fractions = new float[colors.length];
		for (int i = 0; i < colors.length; i++) {
			colors[i] = colorSpaces[rand.nextInt(colorSpaces.length)];
			fractions[i] = rand.nextFloat();
		}
		Arrays.sort(fractions);

		// Color c = getRandColor(200, 250);
		Color c = new Color(241, 238, 231);
		g2.setColor(c);// 设置背景色
		g2.fillRect(0, 0, w, h);

		// 绘制干扰线
		Random random = new Random();
		g2.setColor(getRandColor(160, 200));// 设置线条的颜色
		for (int i = 0; i < 20; i++) {
			int x = random.nextInt(w - 1);
			int y = random.nextInt(h - 1);
			int xl = random.nextInt(6) + 1;
			int yl = random.nextInt(12) + 1;
			g2.drawLine(x, y, x + xl + 40, y + yl + 20);
		}

		// 添加噪点
		float yawpRate = 0.05f;// 噪声率
		int area = (int) (yawpRate * w * h);
		for (int i = 0; i < area; i++) {
			int x = random.nextInt(w);
			int y = random.nextInt(h);
			int rgb = getRandomIntColor();
			image.setRGB(x, y, rgb);
		}

		shear(g2, w, h, c);// 使图片扭曲

		// g2.setColor(getRandColor(100, 160));
		g2.setColor(new Color(208, 153, 153));
		int fontSize = h - 4;
		Font font = new Font("Algerian", Font.ITALIC, fontSize);
		g2.setFont(font);
		char[] chars = code.toCharArray();
		for (int i = 0; i < verifySize; i++) {
			AffineTransform affine = new AffineTransform();
			affine.setToRotation(Math.PI / 4 * rand.nextDouble() * (rand.nextBoolean() ? 1 : -1),
					(w / verifySize) * i + fontSize / 2, h / 2);
			g2.setTransform(affine);
			g2.translate(5, 5);
			g2.drawChars(chars, i, 1, ((w - 10) / verifySize) * i + 5, h / 2 + fontSize / 2 - 10);
		}

		g2.dispose();
		ImageIO.write(image, "jpg", os);
	}

	private static Color getRandColor(int fc, int bc) {
		if (fc > 255)
			fc = 255;
		if (bc > 255)
			bc = 255;
		int r = fc + random.nextInt(bc - fc);
		int g = fc + random.nextInt(bc - fc);
		int b = fc + random.nextInt(bc - fc);
		return new Color(r, g, b);
	}

	private static int getRandomIntColor() {
		int[] rgb = getRandomRgb();
		int color = 0;
		for (int c : rgb) {
			color = color << 8;
			color = color | c;
		}
		return color;
	}

	private static int[] getRandomRgb() {
		int[] rgb = new int[3];
		for (int i = 0; i < 3; i++) {
			rgb[i] = random.nextInt(255);
		}
		return rgb;
	}

	private static void shear(Graphics g, int w1, int h1, Color color) {
		/*
		 * shearX(g, w1, h1, color); shearY(g, w1, h1, color);
		 */
	}

	private static void shearX(Graphics g, int w1, int h1, Color color) {

		int period = random.nextInt(2);

		boolean borderGap = true;
		int frames = 1;
		int phase = random.nextInt(2);

		for (int i = 0; i < h1; i++) {
			double d = (double) (period >> 1)
					* Math.sin((double) i / (double) period + (6.2831853071795862D * (double) phase) / (double) frames);
			g.copyArea(0, i, w1, 1, (int) d, 0);
			if (borderGap) {
				g.setColor(color);
				g.drawLine((int) d, i, 0, i);
				g.drawLine((int) d + w1, i, w1, i);
			}
		}

	}

	private static void shearY(Graphics g, int w1, int h1, Color color) {

		int period = random.nextInt(40) + 10; // 50;

		boolean borderGap = true;
		int frames = 20;
		int phase = 7;
		for (int i = 0; i < w1; i++) {
			double d = (double) (period >> 1)
					* Math.sin((double) i / (double) period + (6.2831853071795862D * (double) phase) / (double) frames);
			g.copyArea(i, 0, 1, h1, 0, (int) d);
			if (borderGap) {
				g.setColor(color);
				g.drawLine(i, (int) d, i, 0);
				g.drawLine(i, (int) d + h1, i, h1);
			}

		}

	}

}
4.展现结果