struts2验证码实现
话不多说直接上代码！
jsp中验证码源文件：
<a id="ptr" href="javascript:;"><img height="27px" alt="struts2验证码兑现" src="<%=request.getContextPath() %>/getVerifyCode" id="prtImg"/></a>
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struts配置文件：
<!-- 验证码 --><action name="getVerifyCode" method="getVerifyCode" ><result type="stream"> <param name="contentType">image/jpeg</param> <param name="inputName">inputStream</param> </result> </action>
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java代码：
import java.awt.Color;import java.awt.Font;import java.awt.Graphics;import java.awt.image.BufferedImage;import java.io.ByteArrayInputStream;import java.io.ByteArrayOutputStream;import java.io.IOException;import java.util.Random;import javax.imageio.ImageIO;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import org.apache.struts2.ServletActionContext;import com.opensymphony.xwork2.ActionSupport;/** * 类描述：验证码生成 * * @author ming.li * @time 2011-4-21 上午11:30:45 */public class VerifyCodeAction extends ActionSupport {/** 版本号 */private static final long serialVersionUID = 5090480110300205197L;/** 文件输入流 */private ByteArrayInputStream inputStream;/** 随机数 */private static final Random random = new Random();/** MD5加密 */private static final MD5 md5 = new MD5();/** 文本类型 */private static final String CONTENT_TYPE = "image/jpeg";/** 画布宽度 */private static int imgWidth = 60;/** 画布高度 */private static int imgHeight = 20;/** 验证码位数 */private static int imgCount = 4;/** * * 方法描述：获取验证码 * * @author ming.li * @time 2011-4-25 下午01:56:19 * * @return */public String getVerifyCode() {try {this.inputStream = generateImage();} catch (IOException e) {e.printStackTrace();}return SUCCESS;}/** * * 方法描述：输出验证码图片 * * @author ming.li * @time 2011-5-30 下午01:44:04 * * @return */public ByteArrayInputStream getInputStream() {return inputStream;}/** * * 方法描述：输入验证码文件到流中 * * @author ming.li * @time 2011-4-25 下午01:56:29 * * @return * @throws IOException */private ByteArrayInputStream generateImage() throws IOException {HttpServletResponse response = ServletActionContext.getResponse();HttpServletRequest request = ServletActionContext.getRequest();response.setContentType(CONTENT_TYPE);response.setHeader("Pragma", "No-cache");response.setHeader("Cache-Control", "no-cache");response.setDateHeader("Expires", 0);// PrintWriter out = response.getWriter();int width = imgWidth, height = imgHeight;BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);// 获取图形上下文Graphics g = image.getGraphics();// 设定背景色g.setColor(getRandColor(200, 250));g.setColor(new Color(255, 255, 255));g.fillRect(0, 0, width, height);// 设定字体g.setFont(new Font("Times New Roman", Font.PLAIN, 18));// 画边框g.setColor(getRandColor(200, 250));g.drawRect(0, 0, width - 1, height - 1);// 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到g.setColor(getRandColor(160, 200));for (int i = 0; i < 10; i++) {int x = random.nextInt(width);int y = random.nextInt(height);int xl = random.nextInt(100);int yl = random.nextInt(12);g.drawLine(x, y, x + xl, y + yl);}// 取随机产生的认证码(4位数字)StringBuffer randSB = new StringBuffer();for (int i = 0; i < imgCount; i++) {String rand = String.valueOf(random.nextInt(10));randSB.append(rand);// 将认证码显示到图象中g.setColor(new Color(20 + random.nextInt(110), 20 + random.nextInt(110), 20 + random.nextInt(110))); // 调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成g.drawString(rand, 13 * i + 6, 16);}// 将认证码存入SESSIONString randMD5 = md5.getMD5ofStr(randSB.toString());request.getSession().setAttribute(Constants.VERFIY_CODE, randMD5);// 图象生效g.dispose();ByteArrayOutputStream bos = new ByteArrayOutputStream();ImageIO.write(image, "JPEG", bos);byte[] buf = bos.toByteArray();return new ByteArrayInputStream(buf);}/** * * 方法描述：给定范围获得随机颜色 * * @author ming.li * @time 2011-4-25 下午01:56:55 * * @param fc * @param bc * @return */private static Color getRandColor(int fc, int bc) {// Random random = new Random();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);}}?