验证码

生成验证码图片的Servlet类

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

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.worthtech.app.web.cookie.AuthCodeCookie;

public class AuthImg extends HttpServlet {
	private static final String CONTENT_TYPE = "text/html; charset=UTF-8";

	private Font mFont;

	public AuthImg() {
		mFont = new Font("Times New Roman", 0, 18);
	}

	public void init() throws ServletException {
	}

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		String authCode = genAuthCode(4);
		AuthCodeCookie authCodeCookie = new AuthCodeCookie(request, response);
		authCodeCookie.addAuthCode(authCode);//保存验证码到cookies
		response.setContentType("image/jpeg");
		javax.servlet.ServletOutputStream out = response.getOutputStream();
		int width = 60;
		int height = 20;
		BufferedImage image = new BufferedImage(width, height, 1);
		Graphics gra = image.getGraphics();
		Random random = new Random();
		gra.setColor(getRandColor(200, 250));
		gra.fillRect(1, 1, width, height);
		gra.setColor(getRandColor(160, 200));
		for (int i = 0; i < 155; i++) {
			int x = random.nextInt(width);
			int y = random.nextInt(height);
			int xl = random.nextInt(12);
			int yl = random.nextInt(12);
			gra.drawLine(x, y, x + xl, y + yl);
		}

		gra.setFont(mFont);
		for (int i = 0; i < 4; i++) {
			char c = authCode.charAt(i);
			gra.setColor(new Color(20 + random.nextInt(110), 20 + random.nextInt(110), 20 + random.nextInt(110)));
			gra.drawString(String.valueOf(c), 13 * i + 6, 16);
		}

		gra.dispose();
		ImageIO.write(image, "JPEG", out);
	}

	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);
	}

	public String genAuthCode(int length) {
		if (length < 1)
			return null;
		String strChars[] = { "1", "2", "3", "4", "5", "6", "7", "8", "9" };
		StringBuffer strPassword = new StringBuffer();
		int nRand = (int) Math.round(Math.random() * 100D);
		for (int i = 0; i < length; i++) {
			nRand = (int) Math.round(Math.random() * 100D);
			strPassword.append(strChars[nRand % (strChars.length - 1)]);
		}

		return strPassword.toString();
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doGet(request, response);
	}

	public void destroy() {
	}

}

将验证码保存到Cookie的类

public class AuthCodeCookie {
	private HttpServletRequest request;
	private HttpServletResponse response;
	public AuthCodeCookie(HttpServletRequest request,
			HttpServletResponse response) {
		this.request = request;
		this.response = response;
	}

	public void addAuthCode(String authCode) {
		addCookie("AUTHCODE", authCode);
	}

	public void addCookie(String name, String value) {
		Cookie cookies = new Cookie(name, value);
		cookies.setPath("/");
		cookies.setMaxAge(-1);//设置cookie经过多长秒后被删除。如果0，就说明立即删除。如果是负数就表明当浏览器关闭时自动删除。
		response.addCookie(cookies);
	}
	
	public String getAuthCode(){
		return getCookies("AUTHCODE");
	}
	
	public String getCookies(String cookieName) {
		Cookie[] cookies = request.getCookies();
		Cookie cookie = null;
		try {
			if (cookies != null && cookies.length > 0) {
				for (int i = 0; i < cookies.length; i++) {
					cookie = cookies[i];
					if (cookie.getName().equals(cookieName)) {
						return cookie.getValue();
					}
				}
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
		return "";
	}
}

在html页面需要显示验证码图片的地方这样写：

<input type="text" name="authCode" value="" style="WIDTH: 56px" />
<img id="checkCodeImg" src="authimg" alt="wait..." height="18"/>//这个就是验证码图片了

web.xml中这样配置：

  <servlet>
    <servlet-name>authimg</servlet-name>
    <servlet-class>com.worthtech.app.servlet.AuthImg</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>authimg</servlet-name>
    <url-pattern>/authimg</url-pattern>
  </servlet-mapping>

在java action中可以这样使用：

ActionMessages errors = new ActionMessages();
AuthCodeCookie authCodeCookie = new AuthCodeCookie(request,response);
if (!authCodeCookie.getAuthCode().equals(form.getAuthCode())) {//验证码不正确		
errors.add("error.login.authcode", new ActionMessage("error.login.authcode"));
this.saveErrors(request, errors);
return mapping.getInputForward();
			}