A simple example of jquery implementation without refreshing verification code _jquery

1. Thinking:

The code picture on the page is a servlet, using jquery to implement the asynchronous validation information

2. Documents used

Verifycodeservlet.java-the servlet used to generate pictures

Resultservlet.java-servlet for verifying the correctness of Authenticode

Verifycode.js--Verify the JS file

Jquery.js the source file in the--jquery package

verifycode.jsp--page

3. Code

Verifycodeservlet.java

Java code

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 {//Verify code picture width.  
  
  private int width = 60;  
  The height of the verification code picture.  
  
  private int height = 20;  
  
  Number of authentication code characters private int codecount = 4;  
  
  private int x = 0;  
  
  Font height 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 '};  /** * Initialize validation picture properties
   */public void init () throws servletexception {//) Get initial information/width String strwidth = this from Web.xml.  
    Getinitparameter ("width");  
    Height String strheight = this.getinitparameter ("height");  
  
    Number of characters String Strcodecount = This.getinitparameter ("Codecount"); Converts the configured information to a numeric try {if (strwidth!= null && strwidth.length ()!= 0) {width = Integer.par  
      Seint (Strwidth);  
      } if (strheight!= null && strheight.length ()!= 0) {height = Integer.parseint (strheight); } if (Strcodecount!= null && strcodecount.length ()!= 0) {codecount = Integer.parseint (st  
      Rcodecount);  
    The 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 {//define image buffer BufferedImage buffimg = new BufferedImage (width, height, bufferedimage.type  
    _INT_RGB);  
  
    Graphics2D g = buffimg.creategraphics ();  
  
    Create a random number generator class Random Random = new Random ();  
    Fill the image with a white g.setcolor (color.white);  
  
    G.fillrect (0, 0, width, height);  
    To create a font, the size of the font should be based on the height of the picture.  
    Font font = new Font ("Fixedsys", Font.plain, Fontheight);  
    Sets the font.  
  
    G.setfont (font);  
    Draw a border.  
    G.setcolor (Color.Black);  
  
    G.drawrect (0, 0, width-1, height-1);  
    Randomly generated 160 lines of interference, so that the image of the authentication code is not easily detected by other programs.  
    G.setcolor (Color.Black);  
      for (int i = 0; i < 160 i++) {int x = random.nextint (width);  
      int y = random.nextint (height);  
      int xl = Random.nextint (12);  
      int yl = Random.nextint (12);  
    G.drawline (x, y, X + xl, y + yl);  
    The//Randomcode is used to save the randomly generated verification code so that the user can authenticate after logging in.  
    StringBuffer Randomcode = new StringBuffer (); int red = 0, Green = 0, blue = 0;  
    A validation code that randomly generates CODECOUNT numbers.  
      for (int i = 0; i < Codecount i++) {//Get a randomly generated captcha number.  
      String Strrand = string.valueof (Codesequence[random.nextint (36)]);  
      Produces a random color component to construct a color value, so that the color values of each digit of the output will be different.  
      Red = random.nextint (255);  
      Green = Random.nextint (255);  
  
      Blue = Random.nextint (255);  
      Draws the validation code into the image with a randomly generated color.  
      G.setcolor (New Color (red, green, blue));  
  
      g.DrawString (Strrand, (i + 1) * x, Codey);  
      The resulting four random numbers are grouped together.  
    Randomcode.append (Strrand);  
    ///Save the four-digit CAPTCHA to the session.  
    HttpSession session = Req.getsession ();  
  
    Session.setattribute ("Validatecode", randomcode.tostring ());  
    Disables image caching.  
    Resp.setheader ("Pragma", "No-cache");  
    Resp.setheader ("Cache-control", "No-cache");  
  
    Resp.setdateheader ("Expires", 0);  
  
    Resp.setcontenttype ("Image/jpeg");  
    Outputs the image to the servlet output stream.  
    Servletoutputstream SOS = Resp.getoutputstream ();Imageio.write (buffimg, "JPEG", SOS);  
  Sos.close ();
}} 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 {//Verify code picture width.

 private int width = 60;
 The height of the verification code picture.

 private int height = 20;

 Number of authentication code characters private int codecount = 4;

 private int x = 0;

 Font height 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 '}; /** * Initialize Verify picture properties/public void init () throWS Servletexception {//Web.xml get initial information//width String strwidth = this.getinitparameter ("width");
 Height String strheight = this.getinitparameter ("height");

 Number of characters String Strcodecount = This.getinitparameter ("Codecount");
  Converts the configured information to a numeric 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);
 The catch (NumberFormatException e) {} x = width/(codecount + 1);
 Fontheight = height-2;

 Codey = height-4; } protected void Service (HttpServletRequest req, HttpServletResponse resp) throws Servletexception, Java.io.IOExceptio
 n {//define image buffer BufferedImage buffimg = new BufferedImage (width, height, bufferedimage.type_int_rgb);

 Graphics2D g = buffimg.creategraphics (); Create a random number generator class Random RandOm = new Random ();
 Fill the image with a white g.setcolor (color.white);

 G.fillrect (0, 0, width, height);
 To create a font, the size of the font should be based on the height of the picture.
 Font font = new Font ("Fixedsys", Font.plain, Fontheight);
 Sets the font.

 G.setfont (font);
 Draw a border.
 G.setcolor (Color.Black);

 G.drawrect (0, 0, width-1, height-1);
 Randomly generated 160 lines of interference, so that the image of the authentication code is not easily detected by other programs.
 G.setcolor (Color.Black);
  for (int i = 0; i < 160 i++) {int x = random.nextint (width);
  int y = random.nextint (height);
  int xl = Random.nextint (12);
  int yl = Random.nextint (12);
 G.drawline (x, y, X + xl, y + yl);
 The//Randomcode is used to save the randomly generated verification code so that the user can authenticate after logging in.
 StringBuffer Randomcode = new StringBuffer ();

 int red = 0, green = 0, blue = 0;
 A validation code that randomly generates CODECOUNT numbers.
  for (int i = 0; i < Codecount i++) {//Get a randomly generated captcha number.
  String Strrand = string.valueof (Codesequence[random.nextint (36)]);
  Produces a random color component to construct a color value, so that the color values of each digit of the output will be different.
  Red = random.nextint (255);
  Green = Random.nextint (255);

  Blue = Random.nextint (255);
  Draws the validation code into the image with a randomly generated color. G.setcolor(New Color (red, green, blue));

  g.DrawString (Strrand, (i + 1) * x, Codey);
  The resulting four random numbers are grouped together.
 Randomcode.append (Strrand);
 ///Save the four-digit CAPTCHA to the session.
 HttpSession session = Req.getsession ();

 Session.setattribute ("Validatecode", randomcode.tostring ());
 Disables image caching.
 Resp.setheader ("Pragma", "No-cache");
 Resp.setheader ("Cache-control", "No-cache");

 Resp.setdateheader ("Expires", 0);

 Resp.setcontenttype ("Image/jpeg");
 Outputs the image to the servlet output stream.
 Servletoutputstream SOS = Resp.getoutputstream ();
 Imageio.write (buffimg, "JPEG", SOS);
 Sos.close (); }

}

Resultservlet.java

Java code

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;  
   The public class Resultservlet extends HttpServlet {/** * The Doget method of the servlet. <br> *  
   * This is called when a form has it tag value method equals to get. * @param request the request send by the ' client to the ' server * @param response the response send by the serve  
   R to the client * @throws servletexception If a error occurred * @throws IOException if an error occurred */public void doget (HttpServletRequest request, httpservletresponse response) throws Servletexception, Ioexce  
  ption {doPost (request, response); /** * The DoPost method of the servlet. <br> * This 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 serve  
   R to the client * @throws servletexception If a error occurred * @throws IOException if an error occurred */public void DoPost (HttpServletRequest request, httpservletresponse response) throws Servletexception, Ioexc  
    eption {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 ("Validation code is empty");  
      }else{if (validatec.equals (Verycode)) {out.println ("Verify code correct");  
      }else{out.println ("Validation code error");  
    } 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. <br> *
 Called when a form has its tag value is equals to get. * @param request the request send by the "client to the" server * @param response the response send by the "server to TH" E Client * @throws servletexception If an error occurred * @throws IOException If a error occurred * * public void DoG ET (httpservletrequest request, httpservletresponse response) throws Servletexception, IOException {doPost (request, RE
 Sponse); /** * The DoPost method of the servlet.
 <br> * * This are called when a form has it 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 TH" E Client * @throws SERVLETEXCEPtion if an error occurred * @throws IOException If a 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 ("Validation code is empty");
  }else{if (validatec.equals (Verycode)) {out.println ("Verify code correct");
  }else{out.println ("Validation code error");
 } out.flush ();
 Out.close (); }

}

Verifycode.js

JS Code

function changeimg () {var imgsrc = $ ("#imgObj");  
  var src = imgsrc.attr ("src");  
Imgsrc.attr ("src", Chgurl (SRC));  
  }//timestamp//To make the picture inconsistent each time, the browser does not read the cache, so you need to add the timestamp function chgurl (URL) {var timestamp = (new Date ()). valueof ();  
  url = url.substring (0,17);  
  if ((Url.indexof ("&") >=0)) {url = url + "xtamp=" + 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));
 }//timestamp//To make the picture inconsistent each time, the browser does not read the cache, so you need to add the timestamp function chgurl (URL) {var timestamp = (new Date ()). valueof ();
 url = url.substring (0,17); if ((Url.indexof ("&") >=0)) {url = url + "xtamp= "+ 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 code

 <%@ page language= "java" contenttype= "text/html" Charset=utf-8 "pageencoding=" UT F-8 "%> <!  
  DOCTYPE HTML PUBLIC "-//w3c//dtd HTML 4.01 transitional//en" "Http://www.w3.org/TR/html4/loose.dtd" >  
 

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