JSP——（图片验证码）
一，Servlet生成图片验证码
第一步：创建一个生成图片的ImageServlet类
package com.lmc.servlet;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
public class ImageServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doPost(request,response);
}
}
第二步：创建一个数据缓存图像对象
//其中width表示图像的宽度，height表示图像的高度，最后一个参数表示图像字节灰度图像
BufferedImage b = new BufferedImage(width, height, BufferedImage.TYPE_BYTE_GRAY);
第三步：获取BufferedImage的绘制对象,再设置一些属性
//获取BufferedImage的绘制对象
Graphics g = b.getGraphics();
//绘制干扰线
for (int i = 0;i < 5; i++){
int x1 = random.nextInt(59);
int y1 = random.nextInt(29);
int x2 = random.nextInt(59);
int y2 = random.nextInt(29);
g.drawLine(x1,y1,x2,y2);
}
// 设置画笔的一些属性（比如颜色、字体风格、背景、前景色等等）
第四步：创建一个图片验证的jsp页面
<%--
Created by IntelliJ IDEA.
User: Administrator
Date: 19/7/26
Time: 14:00
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
Title
图片验证
![]()
代码：
package com.lmc.servlet;
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;
public class ImageServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html;charset=utf-8");
//创建一个数据缓存图像对象
BufferedImage b = new BufferedImage (60, 30, BufferedImage.TYPE_BYTE_GRAY);
//创建字符源
String charSourses = "abcdefghijklmnopqrstuvwxyz0123456789";
String numStr = "";
Random random = new Random();
for (int i = 0;i < 4; i++){
int num = random.nextInt(charSourses.length() - 1);
numStr += charSourses.substring(num,num+1);
}
//获取BufferedImage的绘制对象
Graphics g = b.getGraphics();
//绘制干扰线
for (int i = 0;i < 5; i++){
int x1 = random.nextInt(59);
int y1 = random.nextInt(29);
int x2 = random.nextInt(59);
int y2 = random.nextInt(29);
g.drawLine(x1,y1,x2,y2);
}
// 设置画笔的一些属性（比如颜色、字体风格、背景、前景色等等）
g.drawString(numStr, 12, 19);
request.getSession().setAttribute("checkCode",numStr);
ImageIO.write(b, "jpg",response.getOutputStream());
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doPost(request,response);
}
}
二，使用Kaptcha插件生成验证码
1. 导入相应的jar包
kaptcha-2.3.jar
2. 写一个生成验证码图片的servlet
package com.eight.servlet;
import com.google.code.kaptcha.Producer;
import com.google.code.kaptcha.util.Config;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Enumeration;
import java.util.Properties;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.servlet.Servlet;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
public class KaptchaServlet extends HttpServlet implements Servlet {
private Properties props;
private Producer kaptchaProducer;
private String sessionKeyValue;
public KaptchaServlet() {
this.props = new Properties();
this.kaptchaProducer = null;
this.sessionKeyValue = null;
}
public void init(ServletConfig conf) throws ServletException {
super.init(conf);
ImageIO.setUseCache(false);
Enumeration initParams = conf.getInitParameterNames();
while (initParams.hasMoreElements()) {
String key = (String) initParams.nextElement();
String value = conf.getInitParameter(key);
this.props.put(key, value);
}
Config config = new Config(this.props);
this.kaptchaProducer = config.getProducerImpl();
this.sessionKeyValue = config.getSessionKey();
}
public void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
resp.setDateHeader("Expires", 0L);
resp.setHeader("Cache-Control", "no-store, no-cache, must-revalidate");
resp.addHeader("Cache-Control", "post-check=0, pre-check=0");
resp.setHeader("Pragma", "no-cache");
resp.setContentType("image/jpeg");
String capText = this.kaptchaProducer.createText();
String s1 = capText.substring(0, 1);
String s2 = capText.substring(1, 2);
String culs = "+-*";
Random random = new Random();
char cul = culs.charAt(random.nextInt(3));
int r = 0;
switch(cul){
case '+':
r = Integer.valueOf(s1).intValue() + Integer.valueOf(s2).intValue();
break;
case '-':
r = Integer.valueOf(s1).intValue() - Integer.valueOf(s2).intValue();
break;
case '*':
r = Integer.valueOf(s1).intValue() * Integer.valueOf(s2).intValue();
break;
}
req.getSession().setAttribute(this.sessionKeyValue, String.valueOf(r));
BufferedImage bi = this.kaptchaProducer.createImage(s1 + cul + s2 + "=?");
ServletOutputStream out = resp.getOutputStream();
ImageIO.write(bi, "jpg", out);
try {
out.flush();
} finally {
out.close();
}
}
}
第三步：在web.xml上配置一些信息
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">
<servlet>
<servlet-name>Kaptchaservlet-name>
<servlet-class>com.eight.servlet.KaptchaServletservlet-class>
<init-param>
<description>图片边框，合法值：yes , nodescription>
<param-name>kaptcha.borderparam-name>
<param-value>yesparam-value>
init-param>
<init-param>
<description>
边框颜色，合法值： r,g,b (and optional alpha) 或者 white,black,blue.
description>
<param-name>kaptcha.border.colorparam-name>
<param-value>blackparam-value>
init-param>
<init-param>
<description>边框厚度，合法值：>0description>
<param-name>kaptcha.border.thicknessparam-name>
<param-value>1param-value>
init-param>
<init-param>
<description>图片宽 200description>
<param-name>kaptcha.image.widthparam-name>
<param-value>200param-value>
init-param>
<init-param>
<description>图片高 50description>
<param-name>kaptcha.image.heightparam-name>
<param-value>50param-value>
init-param>
<init-param>
<description>图片实现类description>
<param-name>kaptcha.producer.implparam-name>
<param-value> com.google.code.kaptcha.impl.DefaultKaptcha param-value>
init-param>
<init-param>
<description>文本实现类description>
<param-name>kaptcha.textproducer.implparam-name>
<param-value>
com.google.code.kaptcha.text.impl.DefaultTextCreator
param-value>
init-param>
<init-param>
<description>文本集合，验证码值从此集合中获取description>
<param-name>kaptcha.textproducer.char.stringparam-name>
<param-value>1234567890param-value>
init-param>
<init-param>
<description>验证码长度 5description>
<param-name>kaptcha.textproducer.char.lengthparam-name>
<param-value>2param-value>
init-param>
<init-param>
<description>字体 Arial, Courierdescription>
<param-name>kaptcha.textproducer.font.namesparam-name>
<param-value>Arial, Courierparam-value>
init-param>
<init-param>
<description>字体大小 40px.description>
<param-name>kaptcha.textproducer.font.sizeparam-name>
<param-value>40param-value>
init-param>
<init-param>
<description> 字体颜色，合法值： r,g,b 或者 white,black,blue. description>
<param-name>kaptcha.textproducer.font.colorparam-name>
<param-value>blackparam-value>
init-param>
<init-param>
<description>文字间隔 2description>
<param-name>kaptcha.textproducer.char.spaceparam-name>
<param-value>2param-value>
init-param>
<init-param>
<description>干扰实现类description>
<param-name>kaptcha.noise.implparam-name>
<param-value>
com.google.code.kaptcha.impl.DefaultNoise
param-value>
init-param>
<init-param>
<description> 干扰颜色，合法值： r,g,b 或者 white,black,blue. description>
<param-name>kaptcha.noise.colorparam-name>
<param-value>blackparam-value>
init-param>
<init-param>
<description>
图片样式： 水纹com.google.code.kaptcha.impl.WaterRipple 鱼眼com.google.code.kaptcha.impl.FishEyeGimpy 阴影com.google.code.kaptcha.impl.ShadowGimpy
description>
<param-name>kaptcha.obscurificator.implparam-name>
<param-value> com.google.code.kaptcha.impl.WaterRipple param-value>
init-param>
<init-param>
<description>背景实现类description>
<param-name>kaptcha.background.implparam-name>
<param-value> com.google.code.kaptcha.impl.DefaultBackground param-value>
init-param>
<init-param>
<description>背景颜色渐变，开始颜色description>
<param-name>kaptcha.background.clear.fromparam-name>
<param-value>greenparam-value>
init-param>
<init-param>
<description>背景颜色渐变，结束颜色description>
<param-name>kaptcha.background.clear.toparam-name>
<param-value>whiteparam-value>
init-param>
<init-param>
<description>文字渲染器description>
<param-name>kaptcha.word.implparam-name>
<param-value>
com.google.code.kaptcha.text.impl.DefaultWordRenderer
param-value>
init-param>
<init-param>
<description> session中存放验证码的key键 description>
<param-name>kaptcha.session.keyparam-name>
<param-value>KAPTCHA_SESSION_KEYparam-value>
init-param>
<init-param>
<description>
The date the kaptcha is generated is put into the HttpSession. This is the key value for that item in the session.
description>
<param-name>kaptcha.session.dateparam-name>
<param-value>KAPTCHA_SESSION_DATEparam-value>
init-param>
servlet>
<servlet-mapping>
<servlet-name>Kaptchaservlet-name>
<url-pattern>/randomcode.jpgurl-pattern>
servlet-mapping>
web-app>
3. 在jsp页面写入验证码图片标签和相关js
4. 在登录验证的servlet中判断验证码是否正确
//验证码验证
private void codeCheck(HttpServletRequest request,
HttpServletResponse response) throws IOException {
//创建一个json对象
JSONObject json = new JSONObject();
//获取图片验证码上面的数据
String code = (String) request.getSession()
.getAttribute(com.google.code.kaptcha.Constants.KAPTCHA_SESSION_KEY);
//获取用户输入的验证码数据
String str = request.getParameter("imageCode");
System.out.println(code+" "+str);
if(code.equals(str)){
json.put("status","true");
}else {
json.put("status","error");
}
PrintWriter out = response.getWriter();
out.print(json);
out.flush();
out.close();
}