后台生成图片随机验证码

java后台生成随机验证码并存放session

web.xml配置

<!-- 图片验证码 Validate code -->
<servlet>
<servlet-name>ValidateCodeServlet</servlet-name>
<servlet-class>com.qhwl.common.servlet.ValidateCodeServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>ValidateCodeServlet</servlet-name>
<url-pattern>/servlet/validateCodeServlet</url-pattern>
</servlet-mapping>

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
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 org.apache.commons.lang3.StringUtils;
import org.apache.commons.lang3.math.NumberUtils;
/**
* 生成随机验证码
*/
@SuppressWarnings("serial")
public class ValidateCodeServlet extends HttpServlet {
public static final String VALIDATE_CODE = "validateCode";
private int w = 70;
private int h = 26;
public ValidateCodeServlet() {
super();
}
public void destroy() {
super.destroy();
}
public static boolean validate(HttpServletRequest request, String validateCode) {
String code = (String) request.getSession().getAttribute(VALIDATE_CODE);
return validateCode.toUpperCase().equals(code);
}
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String validateCode = request.getParameter(VALIDATE_CODE);
if (StringUtils.isNotBlank(validateCode)) {
response.getOutputStream().print(validate(request, validateCode) ? "true" : "false");
} else {
this.doPost(request, response);
}
}
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
createImage(request, response);
}
private void createImage(HttpServletRequest request, HttpServletResponse response) throws IOException {
response.setHeader("Pragma", "no-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
response.setContentType("image/jpeg");
/*
* 得到参数高，宽，都为数字时，则使用设置高宽，否则使用默认值
*/
String width = request.getParameter("width");
String height = request.getParameter("height");
if (StringUtils.isNumeric(width) && StringUtils.isNumeric(height)) {
w = NumberUtils.toInt(width);
h = NumberUtils.toInt(height);
}
BufferedImage image = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
Graphics g = image.getGraphics();
/*
* 生成背景
*/
createBackground(g);
/*
* 生成字符
*/
String s = createCharacter(g);
request.getSession().setAttribute(VALIDATE_CODE, s);
//
Session session = UserUtils.getSession();
//
session.setAttribute(VALIDATE_CODE, s);
g.dispose();
OutputStream out = response.getOutputStream();
ImageIO.write(image, "JPEG", out);
out.close();
}
private Color getRandColor(int fc, int bc) {
int f = fc;
int b = bc;
Random random = new Random();
if (f > 255) {
f = 255;
}
if (b > 255) {
b = 255;
}
return new Color(f + random.nextInt(b - f), f + random.nextInt(b - f), f + random.nextInt(b - f));
}
private void createBackground(Graphics g) {
// 填充背景
g.setColor(getRandColor(220, 250));
g.fillRect(0, 0, w, h);
// 加入干扰线条
for (int i = 0; i < 8; i++) {
g.setColor(getRandColor(40, 150));
Random random = new Random();
int x = random.nextInt(w);
int y = random.nextInt(h);
int x1 = random.nextInt(w);
int y1 = random.nextInt(h);
g.drawLine(x, y, x1, y1);
}
}
private String createCharacter(Graphics g) {
char[] codeSeq = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'J', 'K', 'M', 'N', 'P', 'Q', 'R', 'S', 'T', 'U',
'V', 'W', 'X', 'Y', 'Z', '2', '3', '4', '5', '6', '7', '8', '9' };
String[] fontTypes = { "Arial", "Arial Black", "AvantGarde Bk BT", "Calibri" };
Random random = new Random();
StringBuilder s = new StringBuilder();
for (int i = 0; i < 4; i++) {
String r = String.valueOf(codeSeq[random.nextInt(codeSeq.length)]);// random.nextInt(10));
g.setColor(new Color(50 + random.nextInt(100), 50 + random.nextInt(100), 50 + random.nextInt(100)));
g.setFont(new Font(fontTypes[random.nextInt(fontTypes.length)], Font.BOLD, 26));
g.drawString(r, 15 * i + 5, 19 + random.nextInt(8));
// g.drawString(r, i*w/4, h-5);
s.append(r);
}
return s.toString();
}
}

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