java生成图片验证码

utils代码：

package com.yunlian.utils;

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 {

	// 使用到Algerian字体，系统里没有的话需要安装字体，字体只显示大写，去掉了1,0,i,o几个容易混淆的字符
	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) {
		int codesLen = VERIFY_CODES.length();
		Random rand = new Random(System.currentTimeMillis());
		StringBuilder verifyCode = new StringBuilder(verifySize);
		for (int i = 0; i < verifySize; i++) {
			verifyCode.append(VERIFY_CODES.charAt(rand.nextInt(codesLen - 1)));
		}
		return verifyCode.toString();
	}

	/**
	 * 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);

		g2.setColor(Color.GRAY);// 设置边框色
		g2.fillRect(0, 0, w, h);

		Color c = getRandColor(200, 250);
		g2.setColor(c);// 设置背景色
		g2.fillRect(0, 2, w, h - 4);

		// 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));
		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.drawChars(chars, i, 1, ((w - 10) / verifySize) * i + 5, h / 2 + fontSize / 2 - 5);
		}

		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;
	}

	/**
	 * 使图片扭曲
	 * 
	 * @param g
	 * @param w1
	 * @param h1
	 * @param color
	 */
	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);
			}

		}

	}
}

 servlet代码：

package com.yunlian.controller;

import java.io.IOException; 

import javax.servlet.ServletException; 
import javax.servlet.http.HttpServletRequest; 
import javax.servlet.http.HttpServletResponse; 
import javax.servlet.http.HttpSession;

import com.yunlian.utils.VerifyCodeUtils;
/**
 * 生成图片验证码
 * @author Administrator
 *
 */
public class AuthImage extends javax.servlet.http.HttpServlet implements javax.servlet.Servlet { 
    static final long serialVersionUID = 1L; 
   
    public void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 
        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("verCode");
        session.setAttribute("verCode", verifyCode.toLowerCase()); 
        //生成图片 
        int w = 100, h = 30; 
        VerifyCodeUtils.outputImage(w, h, response.getOutputStream(), verifyCode); 
    } 
}

 web.xml配置：

  <servlet>
    <servlet-name>AuthImage</servlet-name>
    <servlet-class>com.yunlian.controller.AuthImage</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>AuthImage</servlet-name>
    <url-pattern>/authImage</url-pattern>
  </servlet-mapping>

 前端代码：

<%@ page language="java" contentType="text/html; charset=UTF-8"
	pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
	<!-- 验证码 -->
	<img id="img" src="authImage" />
	<a href='#' onclick="javascript:changeImg()" >
		<label >看不清？</label>
	</a>


	<!-- 触发JS刷新-->
	<script type="text/javascript">
		function changeImg() {
			var img = document.getElementById("img");
			img.src = "authImage?date=" + new Date();
		}
	</script>
</body>
</html>