Java implementation Verification code making one of your own hands

Before the verification code are now looking for the current use, the following is their own follow-up code to fix, record, share to everyone.

I'm using a servlet here, and the servlet code is as follows

Import Java.awt.Color;
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;

public class Imageservlet extends HttpServlet {

@Override
protected void Doget (HttpServletRequest req, HttpServletResponse resp)
Throws Servletexception, IOException {
BufferedImage bi=new bufferedimage (68,22, BUFFEREDIMAGE.TYPE_INT_RGB);
Graphics G=bi.getgraphics ();
Color C=new color (200,150,255);
G.setcolor (c);
G.fillrect (0, 0, 68, 22);//Wide Height

Set the character of the Verification code
Char[] ch= "QWERTYUIOPASDFGHJKLZXCVBNM0123456789". ToCharArray ();
Random r=new random ();
int len=ch.length,index;
StringBuffer sb=new StringBuffer ();

for (int i=0;i<4;i++) {
Index=r.nextint (len);
Set each font to a different color
G.setcolor (New Color (R.nextint), R.nextint (188), R.nextint (255));
g.DrawString (ch[index]+ "", (i*15) +3,18);//Drawing
Sb.append (Ch[index]);//Record Verification code
}
Req.getsession (). SetAttribute ("Piccode", sb.tostring ());//Save to session scope
Imageio.write (BI, "JPG", Resp.getoutputstream ()); Write to the corresponding page
Super.doget (req, resp);
}

@Override
protected void DoPost (HttpServletRequest req, HttpServletResponse resp)
Throws Servletexception, IOException {
Doget (req, resp);
}
}

In the servlet above, each generated verification code is saved in the session.

Req.getsession (). SetAttribute ("Piccode", sb.tostring ());

When the user submits, we can go through

String code=req.getsession (). getattribute ("Piccode");

To obtain the generated verification code and user-filled verification code to compare

Configuration in Web. xml

<servlet>
<servlet-name>ImageServlet</servlet-name>
<servlet-class>com.test.servlet.ImageServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>ImageServlet</servlet-name>
<url-pattern>/image.do</url-pattern>
</servlet-mapping>

<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>

Index.jsp page Code

<form action= "<%=request.getcontextpath ()%>/login.do" method= "Get" >
<center>
<div>
CAPTCHA: <input type= "text" name= "Code1"/>
/image.do" id= "Code1" onclick= "Relodcode (This, ' image.do ') ) "/>
</div>
<input type= "Submit" value= "Submission"/>
</center>
</form>
<script type= "Text/javascript" >
function Relodcode (obj,url) {
var time=new Date ();
Obj.src= "<%=request.getcontextpath ()%>/" +url+ "? time=" +time;
}
</script>

(Click Verification Code Refresh)

Described above is to write their own, but we generally use to use the verification code when the general will use some plug-ins, the next article to introduce the use of Kaptcha verification code

Java implementation Verification code making one of your own hands