jquery实现无刷新验证码的简单实例_jquery

1. 思路:

页面上的验证码图片是servlet,采用jquery实现异步校验信息

2. 所用到的文件

VerifyCodeServlet.java --用于生成图片的servlet

ResultServlet.java --用于校验验证码正确性的servlet

verifyCode.js --校验的js文件

jquery.js --jquery包里的源文件

verifyCode.jsp --页面

3. 代码

VerifyCodeServlet.java

Java代码

import java.awt.Color;  
import java.awt.Font;  
import java.awt.Graphics2D;  
import java.awt.image.BufferedImage;  
import java.util.Random;  
  
import javax.imageio.ImageIO;  
import javax.servlet.ServletException;  
import javax.servlet.ServletOutputStream;  
import javax.servlet.http.HttpServlet;  
import javax.servlet.http.HttpServletRequest;  
import javax.servlet.http.HttpServletResponse;  
import javax.servlet.http.HttpSession;  
  
public class VerifyCodeServlet extends HttpServlet {  
  
  // 验证码图片的宽度。  
  private int width = 60;  
  
  // 验证码图片的高度。  
  private int height = 20;  
  
  // 验证码字符个数  
  private int codeCount = 4;  
  
  private int x = 0;  
  
  // 字体高度  
  private int fontHeight;  
  
  private int codeY;  
  
  char[] codeSequence = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',  
      'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W',  
      'X', 'Y', 'Z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' };  
  
  /**  
   * 初始化验证图片属性  
   */  
  public void init() throws ServletException {  
    // 从web.xml中获取初始信息  
    // 宽度  
    String strWidth = this.getInitParameter("width");  
    // 高度  
    String strHeight = this.getInitParameter("height");  
    // 字符个数  
    String strCodeCount = this.getInitParameter("codeCount");  
  
    // 将配置的信息转换成数值  
    try {  
      if (strWidth != null && strWidth.length() != 0) {  
        width = Integer.parseInt(strWidth);  
      }  
      if (strHeight != null && strHeight.length() != 0) {  
        height = Integer.parseInt(strHeight);  
      }  
      if (strCodeCount != null && strCodeCount.length() != 0) {  
        codeCount = Integer.parseInt(strCodeCount);  
      }  
    } catch (NumberFormatException e) {  
    }  
  
    x = width / (codeCount + 1);  
    fontHeight = height - 2;  
    codeY = height - 4;  
  
  }  
  
  protected void service(HttpServletRequest req, HttpServletResponse resp)  
      throws ServletException, java.io.IOException {  
  
    // 定义图像buffer  
    BufferedImage buffImg = new BufferedImage(width, height,  
        BufferedImage.TYPE_INT_RGB);  
    Graphics2D g = buffImg.createGraphics();  
  
    // 创建一个随机数生成器类  
    Random random = new Random();  
  
    // 将图像填充为白色  
    g.setColor(Color.WHITE);  
    g.fillRect(0, 0, width, height);  
  
    // 创建字体，字体的大小应该根据图片的高度来定。  
    Font font = new Font("Fixedsys", Font.PLAIN, fontHeight);  
    // 设置字体。  
    g.setFont(font);  
  
    // 画边框。  
    g.setColor(Color.BLACK);  
    g.drawRect(0, 0, width - 1, height - 1);  
  
    // 随机产生160条干扰线，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 

ResultServlet.java

Java代码

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;  
  
public class ResultServlet extends HttpServlet {  
  
  /**  
   * The doGet method of the servlet. 
  
   *  
   * This method is called when a form has its tag value method equals to get.  
   *  
   * @param request the request send by the client to the server  
   * @param response the response send by the server to the client  
   * @throws ServletException if an error occurred  
   * @throws IOException if an error occurred  
   */  
  public void doGet(HttpServletRequest request, HttpServletResponse response)  
      throws ServletException, IOException {  
  
    doPost(request, response);  
  }  
  
  /**  
   * The doPost method of the servlet. 
  
   *  
   * This method is called when a form has its tag value method equals to post.  
   *  
   * @param request the request send by the client to the server  
   * @param response the response send by the server to the client  
   * @throws ServletException if an error occurred  
   * @throws IOException if an error occurred  
   */  
  public void doPost(HttpServletRequest request, HttpServletResponse response)  
      throws ServletException, IOException {  
  
    response.setContentType("text/html;charset=utf-8");  
    String validateC = (String) request.getSession().getAttribute("validateCode");  
    String veryCode = request.getParameter("c");  
    PrintWriter out = response.getWriter();  
    if(veryCode==null||"".equals(veryCode)){  
      out.println("验证码为空");  
    }else{  
      if(validateC.equals(veryCode)){  
        out.println("验证码正确");  
      }else{  
        out.println("验证码错误");  
      }  
    }  
    out.flush();  
    out.close();  
  }  
  
} 
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;

public class ResultServlet extends HttpServlet {

 /**
 * The doGet method of the servlet. 

 *
 * This method is called when a form has its tag value method equals to get.
 * 
 * @param request the request send by the client to the server
 * @param response the response send by the server to the client
 * @throws ServletException if an error occurred
 * @throws IOException if an error occurred
 */
 public void doGet(HttpServletRequest request, HttpServletResponse response)
  throws ServletException, IOException {

 doPost(request, response);
 }

 /**
 * The doPost method of the servlet. 

 *
 * This method is called when a form has its tag value method equals to post.
 * 
 * @param request the request send by the client to the server
 * @param response the response send by the server to the client
 * @throws ServletException if an error occurred
 * @throws IOException if an error occurred
 */
 public void doPost(HttpServletRequest request, HttpServletResponse response)
  throws ServletException, IOException {

 response.setContentType("text/html;charset=utf-8");
 String validateC = (String) request.getSession().getAttribute("validateCode");
 String veryCode = request.getParameter("c");
 PrintWriter out = response.getWriter();
 if(veryCode==null||"".equals(veryCode)){
  out.println("验证码为空");
 }else{
  if(validateC.equals(veryCode)){
  out.println("验证码正确");
  }else{
  out.println("验证码错误");
  }
 }
 out.flush();
 out.close();
 }

}

verifyCode.js

Js代码

function changeImg(){  
  var imgSrc = $("#imgObj");  
  var src = imgSrc.attr("src");  
  imgSrc.attr("src",chgUrl(src));  
}  
//时间戳  
//为了使每次生成图片不一致，即不让浏览器读缓存，所以需要加上时间戳  
function chgUrl(url){  
  var timestamp = (new Date()).valueOf();  
  url = url.substring(0,17);  
  if((url.indexOf("&")>=0)){  
    url = url + "×tamp=" + timestamp;  
  }else{  
    url = url + "?timestamp=" + timestamp;  
  }  
  return url;  
}  
  
function isRightCode(){  
  var code = $("#veryCode").attr("value");  
  code = "c=" + code;  
  $.ajax({  
    type:"POST",  
    url:"resultServlet",  
    data:code,  
    success:callback  
  });  
}  
  
function callback(data){  
  $("#info").html(data);  
} 
function changeImg(){
 var imgSrc = $("#imgObj");
 var src = imgSrc.attr("src");
 imgSrc.attr("src",chgUrl(src));
}
//时间戳
//为了使每次生成图片不一致，即不让浏览器读缓存，所以需要加上时间戳
function chgUrl(url){
 var timestamp = (new Date()).valueOf();
 url = url.substring(0,17);
 if((url.indexOf("&")>=0)){
 url = url + "×tamp=" + timestamp;
 }else{
 url = url + "?timestamp=" + timestamp;
 }
 return url;
}

function isRightCode(){
 var code = $("#veryCode").attr("value");
 code = "c=" + code;
 $.ajax({
 type:"POST",
 url:"resultServlet",
 data:code,
 success:callback
 });
}

function callback(data){
 $("#info").html(data);
}

verifyCode.jsp

Html代码

  
  
  
    
    换一张  
      
    
 

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