The generation and use of Chinese character verification code

First, create a new Servet to generate the random character verification code

Drawimage.class

Package xwcms.net.service;

Import Java.awt.Color;
Import Java.awt.Font;
Import Java.awt.Graphics;
Import Java.awt.Graphics2D;
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;


/**
* Generate random characters
*
* Available @author XW material Network
*
*/
public class DrawImage extends HttpServlet {
public static final int WIDTH = 120;
public static final int HEIGHT = 30;


public void doget (HttpServletRequest request, httpservletresponse response)
Throws Servletexception, IOException {
This.dopost (request, response);
}


public void DoPost (HttpServletRequest request, httpservletresponse response)
Throws Servletexception, IOException {
Request.setcharacterencoding ("Utf-8");
Response.setcontenttype ("Text/html;charset=utf-8");
Create cache
BufferedImage bi = new BufferedImage (WIDTH, HEIGHT,
BUFFEREDIMAGE.TYPE_INT_RGB);
Get Canvas
Graphics g = bi.getgraphics ();


Set Back Color
SetBackground (g);
Set border
SetBorder (g);
Draw interference Lines
Drawrandomline (g);
Write random number
String random = Drawrandomnum ((graphics2d) g);
The existence of random Chinese characters in the session
Request.getsession (). SetAttribute ("Checkcode", random);
Writing a graphic to a browser
Response.setcontenttype ("Image/jpeg");
Header control browser do not cache
Response.setdateheader ("Expries",-1);
Response.setheader ("Cache-control", "No-cache");
Response.setheader ("Pragma", "No-cache");
Write a picture to a browser
Imageio.write (BI, "JPG", Response.getoutputstream ());
}


/**
* Set Background color
*
* @param g
*/
private void SetBackground (Graphics g) {
Set color
G.setcolor (Color.White);
Fill Area
G.fillrect (0, 0, WIDTH, HEIGHT);


}


/**
* Set Border
*
* @param g
*/
private void SetBorder (Graphics g) {
Set Border color
G.setcolor (Color.Blue);
Border area
G.drawrect (1, 1, WIDTH-2, HEIGHT-2);
}


/**
* Draw Random lines
*
* @param g
*/
private void Drawrandomline (Graphics g) {
Set color
G.setcolor (Color.green);
Set the number of lines and draw lines
for (int i = 0; i < 5; i++) {
int x1 = new Random (). Nextint (WIDTH);
int y1 = new Random (). Nextint (HEIGHT);
int x2 = new Random (). Nextint (WIDTH);
int y2 = new Random (). Nextint (HEIGHT);
G.drawline (x1, y1, x2, y2);
}


}


/**
* Draw Random characters
*
* @param g
* @return
*/
Private String Drawrandomnum (graphics2d g) {
StringBuffer sb = new StringBuffer ();
Set color
G.setcolor (color.red);
Set font
G.setfont (New Font ("Arial", Font.Bold, 20));
Prepare common Chinese character sets
String base = "\u7684\u4e00\u4e86\u662f\u6211\u4e0d\u5728\u4eba\u4eec\u6709\u6765\u4ed6\u8fd9\u4e0a\u7740\u4e2a\ U5730\u5230\u5927\u91cc\u8bf4\u5c31\u53bb\u5b50\u5f97\u4e5f\u548c\u90a3\u8981\u4e0b\u770b\u5929\u65f6\u8fc7\ U51fa\u5c0f\u4e48\u8d77\u4f60\u90fd\u628a\u597d\u8fd8\u591a\u6ca1\u4e3a\u53c8\u53ef\u5bb6\u5b66\u53ea\u4ee5\ U4e3b\u4f1a\u6837\u5e74\u60f3\u751f\u540c\u8001\u4e2d\u5341\u4ece\u81ea\u9762\u524d\u5934\u9053\u5b83\u540e\ U7136\u8d70\u5f88\u50cf\u89c1\u4e24\u7528\u5979\u56fd\u52a8\u8fdb\u6210\u56de\u4ec0\u8fb9\u4f5c\u5bf9\u5f00\ U800c\u5df1\u4e9b\u73b0\u5c71\u6c11\u5019\u7ecf\u53d1\u5de5\u5411\u4e8b\u547d\u7ed9\u957f\u6c34\u51e0\u4e49\ U4e09\u58f0\u4e8e\u9ad8\u624b\u77e5\u7406\u773c\u5fd7\u70b9\u5fc3\u6218\u4e8c\u95ee\u4f46\u8eab\u65b9\u5b9e\ U5403\u505a\u53eb\u5f53\u4f4f\u542c\u9769\u6253\u5462\u771f\u5168\u624d\u56db\u5df2\u6240\u654c\u4e4b\u6700\ U5149\u4ea7\u60c5\u8def\u5206\u603b\u6761\u767d\u8bdd\u4e1c\u5e2d\u6b21\u4eb2\u5982\u88ab\u82b1\u53e3\u653e\ U513f\u5e38\u6c14\u4e94\U7b2c\u4f7f\u5199\u519b\u5427\u6587\u8fd0\u518d\u679c\u600e\u5b9a\u8bb8\u5feb\u660e\u884c\u56e0\u522b\u98de\ U5916\u6811\u7269\u6d3b\u90e8\u95e8\u65e0\u5f80\u8239\u671b\u65b0\u5e26\u961f\u5148\u529b\u5b8c\u5374\u7ad9\ U4ee3\u5458\u673a\u66f4\u4e5d\u60a8\u6bcf\u98ce\u7ea7\u8ddf\u7b11\u554a\u5b69\u4e07\u5c11\u76f4\u610f\u591c\ U6bd4\u9636\u8fde\u8f66\u91cd\u4fbf\u6597\u9a6c\u54ea\u5316\u592a\u6307\u53d8\u793e\u4f3c\u58eb\u8005\u5e72\ U77f3\u6ee1\u65e5\u51b3\u767e\u539f\u62ff\u7fa4\u7a76\u5404\u516d\u672c\u601d\u89e3\u7acb\u6cb3\u6751\u516b\ U96be\u65e9\u8bba\u5417\u6839\u5171\u8ba9\u76f8\u7814\u4eca\u5176\u4e66\u5750\u63a5\u5e94\u5173\u4fe1\u89c9\ U6b65\u53cd\u5904\u8bb0\u5c06\u5343\u627e\u4e89\u9886\u6216\u5e08\u7ed3\u5757\u8dd1\u8c01\u8349\u8d8a\u5b57\ U52a0\u811a\u7d27\u7231\u7b49\u4e60\u9635\u6015\u6708\u9752\u534a\u706b\u6cd5\u9898\u5efa\u8d76\u4f4d\u5531\ U6d77\u4e03\u5973\u4efb\u4ef6\u611f\u51c6\u5f20\u56e2\u5c4b\u79bb\u8272\u8138\u7247\u79d1\u5012\u775b\u5229\ u4e16\u521a\u4e14\u7531\u9001\u5207\u661f\u5bfc\u665a\u8868\u591f\u6574\u8ba4\u54cd\u96ea\u6d41\u672a\u573a\u8be5\u5e76\u5e95\u6df1\u523b\ u5e73\u4f1f\u5fd9\u63d0\u786e\u8fd1\u4eae\u8f7b\u8bb2\u519c\u53e4\u9ed1\u544a\u754c\u62c9\u540d\u5440\u571f\ u6e05\u9633\u7167\u529e\u53f2\u6539\u5386\u8f6c\u753b\u9020\u5634\u6b64\u6cbb\u5317\u5fc5\u670d\u96e8\u7a7f\ U5185\u8bc6\u9a8c\u4f20\u4e1a\u83dc\u722c\u7761\u5174\u5f62\u91cf\u54b1\u89c2\u82e6\u4f53\u4f17\u901a\u51b2\ U5408\u7834\u53cb\u5ea6\u672f\u996d\u516c\u65c1\u623f\u6781\u5357\u67aa\u8bfb\u6c99\u5c81\u7ebf\u91ce\u575a\ U7a7a\u6536\u7b97\u81f3\u653f\u57ce\u52b3\u843d\u94b1\u7279\u56f4\u5f1f\u80dc\u6559\u70ed\u5c55\u5305\u6b4c\ U7c7b\u6e10\u5f3a\u6570\u4e61\u547c\u6027\u97f3\u7b54\u54e5\u9645\u65e7\u795e\u5ea7\u7ae0\u5e2e\u5566\u53d7\ U7cfb\u4ee4\u8df3\u975e\u4f55\u725b\u53d6\u5165\u5cb8\u6562\u6389\u5ffd\u79cd\u88c5\u9876\u6025\u6797\u505c\ U606f\u53e5\u533a\u8863\u822c\u62a5\u53f6\u538b\u6162\u53d4\u80cc\u7ec6 ";
int x = 5;
Control word Count
for (int i = 0; i < 4; i++) {
Set Font rotation angle
int degree = new Random (). Nextint ()% 30;
Interception of Chinese characters
String ch = base.charat (new Random (). Nextint (Base.length ())) + "";
Sb.append (CH);
Forward Angle
G.rotate (Degree * math.pi/180, X, 20);
g.DrawString (CH, x, 20);
Reverse angle
G.rotate (-degree * math.pi/180, X, 20);
x + = 30;
}
return sb.tostring ();
}
}

A simple JSP page

<body>
<table width= "100%" border= "0" cellspacing= "0" cellpadding= "0" >
<tr>
&LT;TD width= ">&nbsp;</td>"
&LT;TD width= "" > Verification Code:</td>
&LT;TD width= "><input id=" Verycode "name=" Verycode "type=" text "class=" Yzm "onkeyup=" Isrightcode () "/> </td>
&LT;TD width= "135" ></td>
<td><a href= "#" onclick= "changeimg ()" > Change </a></td>
<td></td>
</tr>
<tr>
&LT;TD style= "LINE-HEIGHT:38PX; Color: #FF0000; Text-align:center; "colspan=" 4 "id=" info ">&nbsp;</td>
<td></td>
</tr>
</table>



<script type= "Text/javascript" src= "Js/jquery.js" ></script>
<script type= "Text/javascript" src= "Js/verifycode.js" ></script>
</body>

Create a new servlet to determine if the verification code is correct Resultservlet

Resultservlet.class

Package xwcms.net.service;


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 {


/**
*
*/
Private static final long serialversionuid = 1L;


public void doget (HttpServletRequest request, httpservletresponse response)
Throws Servletexception, IOException {


DoPost (request, response);
}


public void DoPost (HttpServletRequest request, httpservletresponse response)
Throws Servletexception, IOException {


Response.setcontenttype ("Text/html;charset=utf-8");


Get the verification code in session
String Validatec = (string) request.getsession (). getattribute (
"Checkcode");


Get Verification code text for a page
String Verycode = Request.getparameter ("C");


PrintWriter out = Response.getwriter ();
if (Verycode = = NULL | | "". Equals (Verycode)) {
Out.println ("Please enter the verification code. ");
} else {
if (Validatec.equals (Verycode)) {
OUT.PRINTLN (1);


Out.write (1);
} else {
Out.println (Validatec + "CAPTCHA input error. ");
}
}
Out.flush ();
Out.close ();
}


}

Use jquery for a click to change a verification code

Click to change a verification code
function changeimg () {
var imgsrc = $ ("#imgObj");
var src = imgsrc.attr ("src");
Imgsrc.attr ("src", Chgurl (SRC));
$ ("#info"). HTML ("");
}
Time stamp
In order to make the picture inconsistent each time, that is, do not let the browser read cache, so you need to add a 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;
}
Verification Code Verification
function Isrightcode () {
var code = $ ("#veryCode"). attr ("value");
Alert (code);
Code = "C=" + code;

Use Ajax to verify that random numbers are correct
$.ajax ({
Type: "POST",
URL: "Resultservlet",
Data:code,
Success:callback
});
}
Verify that the submission or error message is processed later
function callback (data) {
if (data.tostring () ==1)
{
$ ("#info"). HTML ("Verify code is correct");
Return
}else
{
$ ("#info"). HTML (data);
Return
}
}

Summary: The essence of the verification code is to create a servlet image, the verification code needs to verify the contents of the session saved up.

Accept the input from the user and determine if the verification code is correct.