Java implementation of picture verification code specific Codes _java

The example of this article for you to share the Java Image Verification code for your reference, the specific content as follows

Web page Display effect:

index.jsp
to force a picture update in two ways:
1, set the picture output is not cached.
2, with JS change the requested address.

<%@ page language= "java" import= "java.util.*" pageencoding= "Utf-8"%>  

Java code to generate Authenticode automatically

Key classes (the contents of the base section for the following classes)
BufferedImage
ImageIO
Graphics/graphics2d

Import Java.awt.Color;
Import Java.awt.Font;
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 Service (HttpServletRequest req, Httpservletresp
  Onse resp) throws Servletexception, IOException {//System.out.println ("Jinlaile"); Resp.setcontenttype ("Image/jpeg");//jpeg is a picture format.
  Set the response content to the type of JPEG picture int width=64;
  int height=40;
  BufferedImage bimg=new bufferedimage (width, height, bufferedimage.type_int_rgb);

  Graphics G=bimg.getgraphics ();
  Background g.setcolor (color.white);
  G.fillrect (0, 0, width, height);
  Font color g.setfont (new font ("AA", font.bold,18));
  Generate verification code with random number: integer Random r=new Random () within 4 0~9; for (int i=0;i<=4;i++) {int t=R.nextint (10); random integer int y=10+r.nextint (20) within//10;/up/down position: 10~30 color C=new color (r.nextint (255), R.nextint (255), r.ne
   Xtint (255));
   G.setcolor (c);
  g.DrawString ("" +t, i*16, y);
   ///Draw interference line for (int i=1;i<8;i++) {color C=new color (r.nextint (255), R.nextint (255), R.nextint (255));
   G.setcolor (c);
  G.drawline (R.nextint (width), r.nextint (height), r.nextint (width), r.nextint (height));
  ///Brush the graph to the Bimg object G.dispose ()//The Close () method in IO is with automatic flush ();
 Imageio.write (bimg, "JPEG", Resp.getoutputstream ());//RESP Get Req object, the encapsulation of socket to client, write to client}

Web.xml

<?xml version= "1.0" encoding= "UTF-8"?> <web-app version= "3.0" xmlns= "Http://java.sun.com/xml/ns/javaee" xml Ns:xsi= "Http://www.w3.org/2001/XMLSchema-instance" xsi:schemalocation= "Http://java.sun.com/xml/ns/javaee http:// Java.sun.com/xml/ns/javaee/web-app_3_0.xsd "> <display-name></display-name> <!-- Access b.jsp files in the security directory Web-inf--> <servlet> <servlet-name>bbbb</servlet-name> <jsp-file>/ Web-inf/b.jsp</jsp-file> </servlet> <!--access to the Java code for generating Authenticode--> <servlet> <servlet-name> Img</servlet-name> <servlet-class>cn.hncu.servlet.ImageServlet</servlet-class> </servlet > <servlet-mapping> <servlet-name>bbbb</servlet-name> <url-pattern>/bb.asp</ url-pattern> </servlet-mapping> <servlet-mapping> <servlet-name>img</servlet-name> < Url-pattern>/confirm</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> </web-app>