jsp页面验证码demo

在java后台中生成验证码的ImageIO传到前端页面显示，同时把验证码的value值传入session 中用于与用户输入的验证码进行匹配，在用户验证中使用ajax技术，在不刷新页面的同时进行验证码验证。

程序结构图：

VerifyCodeUtils程序主要内容为通过java生成验证码的图片，以及验证码的value值，程序如下：

package utils;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.util.HashMap;
import java.util.Map;
import java.util.Random;

public class VerifyCodeUtils {
private static BufferedImage image = null;

  private static Random random = new Random();
  //在自己定义的一些数中，生成4位随机数
  public static String getVerifyCode() {
    String str = "";
    char[] code = new char[]{'A','B','C','D','E','F','G','H','I','J','K','L','M','N','P','Q','R','S','T','U',
      'V','W','X','Y','Z','a','b','c','d','e','f','g','h','i','j','k','m','n','p','q','r','s','t',
      'u','v','w','x','y','z','2','3','4','5','6','7','8','9'};
    Random random = new Random();
    for(int i = 0; i < 4; i++) {
      str += String.valueOf(code[random.nextInt(code.length)]);
    }
    return str;
  }

  //生成验证码图像
  public static Map getVerifyCode(int width, int heigth) {
    VerifyCodeUtils.image = new BufferedImage(width, heigth, BufferedImage.TYPE_INT_RGB);
    Graphics2D g = (Graphics2D) VerifyCodeUtils.image.getGraphics();
    String verifyCode = getVerifyCode();
    Map map = new HashMap();
    map.put("verifyCode", verifyCode);
    //将图像填充为白色
    g.setColor(Color.WHITE);
    g.fillRect(0, 0, width, heigth);
    //设置字体
    g.setFont(new Font("宋体", Font.BOLD + Font.ITALIC, heigth-10));
    //画边框。
    g.setColor(VerifyCodeUtils.getColor());
    g.drawRect(0, 0, width, heigth);
    //随机产生干扰线，使图象中的认证码不易被其它程序探测到
    g.setColor(Color.BLACK);
    for (int i = 0; i < 50; i++) {
      int x = VerifyCodeUtils.random.nextInt(width);
      int y = VerifyCodeUtils.random.nextInt(heigth);
      int xl = VerifyCodeUtils.random.nextInt(5);
      int yl = VerifyCodeUtils.random.nextInt(5);
      g.setColor(getColor());
      g.drawLine(x, y, x + xl, y + yl);
    } 

    char c;
    for(int i = 0; i < 4; i++) {
      c = verifyCode.charAt(i);
      g.drawString(c+"", i*20+40, heigth-10);
    }
    map.put("image", VerifyCodeUtils.image);
    return map;
  }

  //随机化颜色
  public static Color getColor() {
    int red = 0, green = 0, blue = 0;
    // 产生随机的颜色分量来构造颜色值，这样输出的每位数字的颜色值都将不同。
    red = VerifyCodeUtils.random.nextInt(255);
    green = VerifyCodeUtils.random.nextInt(255);
    blue = VerifyCodeUtils.random.nextInt(255);
    return new Color(red,green,blue);
  }
}

VerifyCodeServlet把VerifyCodeUtils生成的验证码图片通过io流传入前端显示，代码如下：

package Servlet;

import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Map;

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;

import utils.VerifyCodeUtils;

/**
 * Servlet implementation class VerifyCodeServlet
 */
@WebServlet("/")
public class VerifyCodeServlet extends HttpServlet {
  private static final long serialVersionUID = 1L;

  /**
   * @see HttpServlet#HttpServlet()
   */
  public VerifyCodeServlet() {
    super();
    // TODO Auto-generated constructor stub
  }

  /**
   * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
   */
  protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    response.setHeader("Expires", "-1");
    response.setHeader("Cache-Control", "no-cache");
    response.setHeader("Pragma", "no-cache");
    response.setHeader("Content-type", "image/jpeg");
    Map map = VerifyCodeUtils.getVerifyCode(223, 50);
    //把verifyCode的数值传入session中用于验证用户输入的验证码是否正确
    request.getSession().setAttribute("verifyCode", map.get("verifyCode").toString().toUpperCase());
    //通过IO流传入前端显示
    ImageIO.write((BufferedImage) map.get("image"), "jpg", response.getOutputStream());
  }

  /**
   * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
   */
  protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    // TODO Auto-generated method stub
    doGet(request, response);
  }

}

页面jsp代码如下：

<%@ 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">
<base id="base" href="${pageContext.request.contextPath}">
<title>验证码测试界面</title>
<style>
div{float:left;}
input{width:223px;height:31px;margin-right:20px;}
img{width:223px;height:35px;}
p{margin:10px;}
</style>
</head>
 <body>
 <script src="${pageContext.request.contextPath}/JS/demo.js"></script>
 <div>
  <input type="text" name="verifyCode" id="verifyCode" placeholder="验证码" onblur="check_verifyCode()">
  </div>
  <div>
    <img src="${pageContext.request.contextPath}/servlet/VerifyCodeServlet" style="width: 100%" onclick="this.src=this.src + '?' + Math.random()"/>
  </div>
  <div>
    <p id = "tip"></p>
  </div>
</body>

</html>

js 实现ajax代码如下：

/**
 *
 */
function check_verifyCode(){
  var XMLHttpReqVerifyCode = null;
  var url =document.getElementById("base").href +"/servlet/TestVerifyCodeServlet";
  var verifyCode = document.getElementById("verifyCode").value;
  var tip = document.getElementById("tip");
  var errorTip = "输入的验证码不正确";
  var successTip = "输入的验证码正确";
  tip.innerHTML=errorTip;
  if(verifyCode==null || verifyCode==""){
    tip.innerHTML=errorTip;
    tip.style.color = "red";
  }else{
    if(window.XMLHttpRequest) {
      //DOM2浏览器
      XMLHttpReqVerifyCode = new XMLHttpRequest();
    } else if(window.ActiveXObject) {
      //使用json语法创建数组
      var MSXML = ['MSXML2.XMLHTTP.5.0', 'MSXML2.XMLHTTP.4.0', 'MSXML2.XMLHTTP.3.0', 'MSXML2.XMLHTTP', 'Microsoft.XMLHTTP'];
      for(var i = 0; i < MSXML.length; i++) {
        try{
          XMLHttpReqVerifyCode = new ActiveXObject(MSXML[i]);
        } catch(e) {

        }
      }
    }
    XMLHttpReqVerifyCode.open("POST",url, true);
    XMLHttpReqVerifyCode.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
    XMLHttpReqVerifyCode.onreadystatechange = function testVerifyCodeServletResponse(){
      if(XMLHttpReqVerifyCode.readyState == 4 && (XMLHttpReqVerifyCode.status == 200 || XMLHttpReqVerifyCode.status == 304)) {
        if(XMLHttpReqVerifyCode.responseText == 1){
          tip.innerHTML = successTip;
          tip.style.color = "green";
        }else if(XMLHttpReqVerifyCode.responseText == 0){
          tip.innerHTML = errorTip;
          tip.style.color = "red";
        }
      }
    }
    XMLHttpReqVerifyCode.send("code="+verifyCode);
  }
  //ajax前后台交互
function createXMLHttpRequest(XMLHttpReq) {
  if(window.XMLHttpRequest) {
    //DOM2浏览器
    XMLHttpReq = new XMLHttpRequest();
  } else if(window.ActiveXObject) {
    //使用json语法创建数组
    var MSXML = ['MSXML2.XMLHTTP.5.0', 'MSXML2.XMLHTTP.4.0', 'MSXML2.XMLHTTP.3.0', 'MSXML2.XMLHTTP', 'Microsoft.XMLHTTP'];
    for(var i = 0; i < MSXML.length; i++) {
      try{
        XMLHttpReq = new ActiveXObject(MSXML[i]);
      } catch(e) {

      }
    }

    return XMLHttpReq;
  }
}

}

TestVerifyCodeServlet与js交互代码为：

package Servlet;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class TestVerifyCodeServlet
 */
@WebServlet("/TestVerifyCodeServlet")
public class TestVerifyCodeServlet extends HttpServlet {
  private static final long serialVersionUID = 1L;

  /**
   * @see HttpServlet#HttpServlet()
   */
  public TestVerifyCodeServlet() {
    super();
    // TODO Auto-generated constructor stub
  }

  /**
   * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
   */
  protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    // TODO Auto-generated method stub

    String codeTrue = (String) request.getSession().getAttribute("verifyCode");
    String codeInput = request.getParameter("code");
    System.out.println(codeInput);
    response.setContentType("text/html;charset=utf-8");
    PrintWriter out = response.getWriter();//打印流
    if(codeInput!=null){
      if(codeInput.toUpperCase().equals(codeTrue)){
        out.println("1");
      }else{
        out.println("0");
      }
    }

  }

  /**
   * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
   */
  protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    // TODO Auto-generated method stub
    doGet(request, response);
  }

}

xml代码为

<?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_2_5.xsd" version="2.5">
 <display-name></display-name>
 <welcome-file-list>
  <welcome-file>demo.jsp</welcome-file>
 </welcome-file-list>
 <servlet>
  <servlet-name>VerifyCodeServlet</servlet-name>
  <servlet-class>Servlet.VerifyCodeServlet</servlet-class>
 </servlet>
 <servlet-mapping>
  <servlet-name>VerifyCodeServlet</servlet-name>
  <url-pattern>/servlet/VerifyCodeServlet</url-pattern>
 </servlet-mapping>
  <servlet>
  <servlet-name>TestVerifyCodeServlet</servlet-name>
  <servlet-class>Servlet.TestVerifyCodeServlet</servlet-class>
 </servlet>
 <servlet-mapping>
  <servlet-name>TestVerifyCodeServlet</servlet-name>
  <url-pattern>/servlet/TestVerifyCodeServlet</url-pattern>
 </servlet-mapping>
</web-app>

结果显示：

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