验证码生成流程
页面
<%@ 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>
<form action="" method="post">
验证码:<input type="text" name="checkcode"/>
<img id="codeImg" onclick="changeImg()" src="${pageContext.request.contextPath }/CheckImgServlet"><br/>
<input type="submit" value="提交">
</form>
</body>
</html>
java代码
简单版
@WebServlet("/CheckImgServlet1")
public class CheckImgServlet1 extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
int width = 120;
int height = 30;
BufferedImage bufferedImage = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
Graphics graphics = bufferedImage.getGraphics();
graphics.setColor(Color.YELLOW);
graphics.fillRect(0, 0, width, height);
graphics.setColor(Color.BLUE);
graphics.drawRect(0, 0, width-1, height-1);
Graphics2D g2d = (Graphics2D)graphics;
g2d.setColor(Color.BLACK);
g2d.setFont(new Font("宋体",Font.BOLD,18));
String words = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
Random random = new Random();
int x = 10;
for(int i=0;i<4;i++){
int idx = random.nextInt(words.length());
char ch = words.charAt(idx);
int jiaodu = random.nextInt(60) - 30;
double theta = jiaodu * Math.PI / 180;
g2d.rotate(theta, x, 20);
g2d.drawString(String.valueOf(ch), x, 20);
g2d.rotate(-theta, x, 20);
x+=30;
}
ImageIO.write(bufferedImage, "jpg", response.getOutputStream());
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
升级版
package com.imooc.web.servlet;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet("/CheckImgServlet")
public class CheckImgServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
int width = 120;
int height = 30;
BufferedImage bufferedImage = new BufferedImage(width, height,
BufferedImage.TYPE_INT_RGB);
Graphics graphics = bufferedImage.getGraphics();
graphics.setColor(getRandColor(200, 250));
graphics.fillRect(0, 0, width, height);
graphics.setColor(Color.WHITE);
graphics.drawRect(0, 0, width - 1, height - 1);
Graphics2D graphics2d = (Graphics2D) graphics;
graphics2d.setFont(new Font("宋体", Font.BOLD, 18));
String words =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890";
Random random = new Random();
StringBuffer sb = new StringBuffer();
int x = 10;
for (int i = 0; i < 4; i++) {
graphics2d.setColor(new Color(20 + random.nextInt(110), 20 + random
.nextInt(110), 20 + random.nextInt(110)));
int jiaodu = random.nextInt(60) - 30;
double theta = jiaodu * Math.PI / 180;
int index = random.nextInt(words.length());
char c = words.charAt(index);
sb.append(c);
graphics2d.rotate(theta, x, 20);
graphics2d.drawString(String.valueOf(c), x, 20);
graphics2d.rotate(-theta, x, 20);
x += 30;
}
request.getSession().setAttribute("checkCode", sb.toString());
graphics.setColor(getRandColor(160, 200));
int x1;
int x2;
int y1;
int y2;
for (int i = 0; i < 30; i++) {
x1 = random.nextInt(width);
x2 = random.nextInt(12);
y1 = random.nextInt(height);
y2 = random.nextInt(12);
graphics.drawLine(x1, y1, x1 + x2, x2 + y2);
}
graphics.dispose();
ImageIO.write(bufferedImage, "jpg", response.getOutputStream());
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
private 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);
}
}
看不清,换一张
<script type="text/javascript">
function changeImg(){
var codeImg = document.getElementById("codeImg");
codeImg.src="${pageContext.request.contextPath }/CheckImgServlet?time="+new Date().getTime();
}
</script>
验证码校验
String code1 = (String)request.getSession().getAttribute(com.google.code.kaptcha.Constants.KAPTCHA_SESSION_KEY);
String code2 = request.getParameter("checkCode");
if(code2==null || !code2.equalsIgnoreCase(code1)){
request.setAttribute("msg", "验证码输入不正确!");
request.getRequestDispatcher("/login.jsp").forward(request, response);
return;
}
Kaptck验证码
配置
<servlet>
<servlet-name>KaptchaServlet</servlet-name>
<servlet-class>com.google.code.kaptcha.servlet.KaptchaServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>KaptchaServlet</servlet-name>
<url-pattern>/KaptchaServlet</url-pattern>
</servlet-mapping>
jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<form action="" method="post">
验证码:<input type="text" name="checkcode"/>
<img id="codeImg" onclick="changeImg()" src="${pageContext.request.contextPath }/KaptchaServlet"><br/>
<input type="submit" value="提交">
</form>
</body>
</html>
看不清换一张
<script type="text/javascript">
function changeImg(){
var codeImg = document.getElementById("codeImg");
codeImg.src="${pageContext.request.contextPath }/KaptchaServlet?time="+new Date().getTime();
}
</script>
属性配置
<servlet>
<servlet-name>KaptchaServlet</servlet-name>
<servlet-class>com.google.code.kaptcha.servlet.KaptchaServlet</servlet-class>
<!-- 修改随机的字母或数字的长度 -->
<init-param>
<param-name>kaptcha.textproducer.char.length</param-name>
<param-value>4</param-value>
</init-param>
<!-- 修改字体大小 -->
<init-param>
<param-name>kaptcha.textproducer.font.size</param-name>
<param-value>25</param-value>
</init-param>
<!-- 修改字体空隙 -->
<init-param>
<param-name>kaptcha.textproducer.char.space</param-name>
<param-value>10</param-value>
</init-param>
<!-- 修改图片的宽高 -->
<init-param>
<param-name>kaptcha.image.width</param-name>
<param-value>120</param-value>
</init-param>
<init-param>
<param-name>kaptcha.image.height</param-name>
<param-value>30</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>KaptchaServlet</servlet-name>
<url-pattern>/KaptchaServlet</url-pattern>
</servlet-mapping>
验证码校验
String code1 = (String)request.getSession().getAttribute(com.google.code.kaptcha.Constants.KAPTCHA_SESSION_KEY);
String code2 = request.getParameter("checkCode");
if(code2==null || !code2.equalsIgnoreCase(code1)){
request.setAttribute("msg", "验证码输入不正确!");
request.getRequestDispatcher("/login.jsp").forward(request, response);
return;
}
