Java EE dynamic Picture verification

form.jsp

<%@ page language= "java"  import= "java.util.*"  pageencoding= "UTF-8"%><%string  path = request.getcontextpath (); String basepath = request.getscheme () + "://" +request.getservername () + ":" +request.getserverport () +path+ "/";%><! doctype html public  "-//w3c//dtd html 4.01 transitional//en" >

Imageproduceservlet.java

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.io.printwriter;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  ImageProduceServlet extends HttpServlet {private static final int  width = 120;private static final int hight = 35;public void  Doget (httpservletrequest request, httpservletresponse response) throws ServletException,  ioexception {bufferedimage image = new bufferedimage (WIDTH, HIGHT,  BUFFEREDIMAGE.TYPE_INT_RGB); Graphics g = image.getgraphics ();//Set backScene color Setbackgroud (g);//Set Border SetBorder (g);//Draw Interference line drawrandomline (g);//write random number and deposit sessionstring random =  drawrandomnum ((graphics2d) g); Request.getsession (). SetAttribute ("Imagecode",  random);// Graphics to Browser response.setcontenttype ("Image/jpeg"); Imageio.write (image,  "JPG",  response.getoutputstream ()) ;} Private void setbackgroud (graphics g)  {g.setcolor (Color.gray); G.fillRect (0, 0,  Width, hight);} Private void setborder (graphics g)  {g.setcolor (Color.Blue); G.drawrect (1,1,WIDTH-2,HIGHT-2) ;} Private void drawrandomline (graphics g)  {g.setcolor (Color.green); for (int i=0;i<5;i + +) {int x1 = new random (). Nextint (WIDTH); Int y1 = new random (). nextInt (HIGHT); Int x2 = new random (). Nextint (WIDTH); Int y2 = new random (). Nextint (HIGHT); G.drawline (X1,y1,x2,y2);}} Private string drawrandomnum (graphics2d g)  {g.setcolor (CoLor. RED); G.setfont (New font ("The song Body", font.bold,20)); string base =  "ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890"; Stringbuffer sb = new stringbuffer (); Int x =5;for (int i=0; i<4;i++) {int degree = new random (). Nextint ()%30;  //-30 degrees ~30 degrees string ch =  base.charat (New random (). Nextint (Base.length ())) + ""; sb.append (ch); G.rotate (degree*math.pi/180,x,20) ; g.drawstring (ch, x, 20); g.rotate (-degree*math.pi/180,x,20);  //ensure rotation is not additive x+=30;} Return sb.tostring ();} Public void dopost (Httpservletrequest request, httpservletresponse response) throws  servletexception, ioexception {doget (Request, response);}}

Imagecheckservlet.java

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 imagecheckservlet extends httpservlet  {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"); Response.setcharacterencoding ("UTF-8"); Request.setcharacterencoding ("UTF-8");//Verify that the authentication code is valid String client_ Code = request.getparameter ("info"); string server_code =  (String)  request. GetSession (). getattribute ("Imagecode");//Not ignoring case if (client_code==null | |  server_code==null | |  !server_code.equals (Client_code)) {System.out.println ("The CAPTCHA is incorrect ..."); return;} SYSTEM.OUT.PRINTLN ("Processing client requests ...");}}

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