实践---java实现生成验证码功能

来源：互联网发布：淘宝退款率高了怎么办编辑：程序博客网时间：2024/06/06 00:11

开始

1.编写验证码图形显示页面

index.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"  pageEncoding="UTF-8"%><!DOCTYPE html ><html><head><meta charset="UTF-8"><title>图片验证码</title></head><script type="text/javascript" src="js/jQuery1.9.1.js"></script><script type="text/javascript">  //功能为重新加载 function reload(){/*通过document对象的getElementById()方法拿到 id名为 image的变量 *通过url传参  new一个 Date对象传入时间 */document.getElementById("image").src="<%=request.getContextPath() %>/imageServlet?date="+new Date().getTime();//Jquery取元素  $()方式     调用.val()传入" " $("#checkcode").val("");   // 将验证码清空}  //  功能为验证码 function verificationcode(){     //生命一个名为 text的变量          通过Jquery方式取得元素   checkcode的值      $("#元素名").val() var text=$.trim($("#checkcode").val()); // $.post("${pageContext.request.contextPath}/verificationServlet",{op:text},function(data){ data=parseInt($.trim(data)); if(data>0){ $("#span").text("验证成功!").css("color","green"); }else{ $("#span").text("验证失败!").css("color","red"); reload();  //验证失败后需要更换验证码 } }); $("#checkcode").val(""); // 将验证码清空 }</script><body>    验证码：<input type="text" name="checkcode"  id="checkcode"/>  <img  src="<%=request.getContextPath() %>/imageServlet" alt="验证码" id="image" /><a href="javascript:reload();"><label>换一张</label></a><br><input  type="button" value="提交"  onclick="javascript:verificationcode()"><span id="span"></span></body></html>

2.编写图片生成的Servlet

ImageServlet.java

package com.dw.servlet;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 javax.servlet.http.HttpSession;public class ImageServlet extends HttpServlet {private static final long serialVersionUID = 1L;       protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//设置字符编码为utf-8request.setCharacterEncoding("utf-8");//画图像BufferedImage bfi = new BufferedImage(85,28,BufferedImage.TYPE_INT_RGB);//Graphics g = bfi.getGraphics();//矩形的坐标g.fillRect(0, 0, 85, 28);//验证码字符范围     字符数组存放char[] ch = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789".toCharArray();//生成随机数Random r = new Random(); //int index;  //StringBufferStringBuffer sb = new StringBuffer(); //保存字符串for(int i=0; i<4; i++){index = r.nextInt(ch.length);//设置颜色//g.setColor(new Color(r.nextInt(255),r.nextInt(255),r.nextInt(255)));g.setColor(new Color(r.nextInt(200),r.nextInt(100),r.nextInt(200)));//设置字体Font font = new Font("宋体", 30, 28);g.setFont(font);g.drawString(ch[index]+"", (i*20)+2, 25);sb.append(ch[index]);}// 添加噪点    int area = (int) (0.02 * 80 * 25);    for(int i=0; i<area; ++i){        int x = (int)(Math.random() * 80);        int y = (int)(Math.random() * 25);        bfi.setRGB(x, y, (int)(Math.random() * 250));    }  //设置验证码中的干扰线    for (int i = 0; i < 6; i++) {        //随机获取干扰线的起点和终点      int xstart = (int)(Math.random() * 80);      int ystart = (int)(Math.random() * 25);      int xend = (int)(Math.random() * 80);      int yend = (int)(Math.random() * 25);      g.setColor(interLine(1, 200));      g.drawLine(xstart, ystart, xend, yend);    }        HttpSession session = request.getSession();  //保存到session    session.setAttribute("verificationCode", sb.toString());    ImageIO.write(bfi, "JPG", response.getOutputStream());  //写到输出流}protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doGet(request,response);}/**   * 获取随机的颜色值，r,g,b的取值在Low到High之间   * @param L 左区间   * @param R 右区间   * @return 返回随机颜色值   */  private static Color interLine(int Low, int High){    if(Low > 255)    Low = 255;    if(High > 255)    High = 255;    if(Low < 0)    Low = 0;    if(High < 0)    High = 0;    int interval = High - Low;     int r = Low + (int)(Math.random() * interval);    int g = Low + (int)(Math.random() * interval);    int b = Low + (int)(Math.random() * interval);    return new Color(r, g, b);  }}

3.验证码的逻辑验证Servlet

Ve'rificationServlet.java

package com.dw.servlet;import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;public class VerificationServlet extends HttpServlet {//生成序列化idprivate static final long serialVersionUID = 1L;       protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//设置字符编码为utf-8response.setCharacterEncoding("utf-8");//设置内容类型  为html   编码格式为utf-8response.setContentType("text/html;charset=utf-8");//通过request对象的getSession()得到session对象     赋值给    HttpSession类型的实例化对象   session  HttpSession session =request.getSession();//从session对象 拿到  名称为verificationCode变量的  字符串类型的 变量String verificationCode = (String)session.getAttribute("verificationCode");//验证码  对象String checkcode = request.getParameter("op");//打印输出字符流                PrintWriter out = response.getWriter();if(checkcode.equals(verificationCode)){out.println(1);}else{out.println(0);}//刷新输出流out.flush();//关闭输出流out.close();}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doPost(request,response);}}

4.web.xml中配置

<?xml version="1.0" encoding="UTF-8"?><web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">  <display-name>verification_code</display-name>    <servlet>                    <!-- 图像Servlet -->  <servlet-name>ImageServlet</servlet-name>  <servlet-class>com.dw.servlet.ImageServlet</servlet-class>  </servlet>  <servlet-mapping>  <servlet-name>ImageServlet</servlet-name>  <!-- 处理的url路径为  相对路径    以/imageServlet开始的 所有请求 -->  <url-pattern>/imageServlet</url-pattern>  </servlet-mapping>      <servlet>                     <!-- 验证Servlet -->  <servlet-name>VerificationServlet</servlet-name>  <servlet-class>com.dw.servlet.VerificationServlet</servlet-class>  </servlet>  <servlet-mapping>  <servlet-name>VerificationServlet</servlet-name>    <url-pattern>/verificationServlet</url-pattern>  </servlet-mapping>                  <!-- 欢迎页      -->  <welcome-file-list>    <welcome-file>index.html</welcome-file>    <welcome-file>index.jsp</welcome-file>  </welcome-file-list></web-app>

结果:

什么都不输入

输入看到的字符

总结：

以上验证码生成以及验证功能

总结

0 0