下面是生成的圖片：
代碼如下，JSP代碼
<%@page contentType="image/jpeg"%> <%@page pageEncoding="UTF-8"%> <%@ page import="java.awt.*,javax.imageio.*,java.io.*,java.util.*,java.awt.image.*" %> <%-- The taglib directive below imports the JSTL library. If you uncomment it, you must also add the JSTL library to the project. The Add Library action on Libraries node in Projects view can be used to add the JSTL 1.1 library. --%> <%-- <%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%> --%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <%!String s="";%> <% java.util.List<String> fonts=new ArrayList<String>(); GraphicsEnvironment.getLocalGraphicsEnvironment().preferLocaleFonts(); String[] names=GraphicsEnvironment.getLocalGraphicsEnvironment().getAvailableFontFamilyNames(Locale.CHINA); 
for(String s:names){ 
char c=s.charAt(0); 
if(Character.isLowerCase(c)||Character.isUpperCase(c)){ 
}else{ fonts.add(s); 
} 
} BufferedImage bi=new BufferedImage(200,50,BufferedImage.TYPE_INT_RGB); Graphics2D g=bi.createGraphics(); char[] cs={'0','1','2','3','4','5','6','7','8','9'}; char[] use=new char[4]; g.setColor(new Color(240,240,240)); g.fillRect(0,0,200,50); for(int i=0;i<4;i++){ Point p=new Point(5+(i*((int)(Math.random()*10)+40)),40); int size=0; int[] sizes=new int[20]; for(int j=0;j<20;j++){ sizes[j]=30+j; } size=sizes[(int)(Math.random()*sizes.length)]; int face=0; if(Math.random()*10>5){ face=Font.BOLD; }else{ face=Font.ITALIC; } use[i]=cs[(int)(Math.random()*cs.length)]; g.setPaint(new GradientPaint(p.x,p.y,new Color((int)(Math.random()*256),0,(int)(Math.random()*256)), p.x,p.y-size,new Color((int)(Math.random()*256),(int)(Math.random()*256),(int)(Math.random()*256)))); g.setFont(new Font(fonts.get((int)(Math.random()*fonts.size())),face,size)); g.drawString(""+use[i],p.x,p.y); } s=new String(use); session.setAttribute("code", s); g.setPaint(null); for(int i=0;i<4;i++){ g.setColor(new Color((int)(Math.random()*0x00FFFFFFF))); g.drawLine((int)(Math.random()*200),(int)(Math.random()*50),(int)(Math.random()*200),(int)(Math.random()*50)); } Random random = new Random(); for (int i=0;i<88;i++) { int x = random.nextInt(200); int y = random.nextInt(50); g.setColor(new Color((int)(Math.random()*0x00FFFFFFF))); g.setStroke(new BasicStroke((float)(Math.random()*3))); g.drawLine(x,y,x,y); } OutputStream ot=response.getOutputStream(); ImageIO.write(bi,"JPEG",ot); g.dispose(); ot.close(); %> /*
* Code.java
*
* Created on 2007年9月21日, 下午12:08
*/
package com.hadeslee; import java.awt.BasicStroke; import java.awt.Color; import java.awt.Font; import java.awt.GradientPaint; import java.awt.Graphics2D; import java.awt.GraphicsEnvironment; import java.awt.Paint; import java.awt.Point; import java.awt.Stroke; import java.awt.image.BufferedImage; import java.io.*; import java.util.ArrayList; import java.util.List; import java.util.Locale; import java.util.Random; import javax.imageio.ImageIO; import javax.servlet.*; import javax.servlet.http.*; /** * * @author lbf * @version */ public class Code extends HttpServlet { /** Processes requests for both HTTP <code>GET</code> and <code>POST</code> methods. * @param request servlet request * @param response servlet response */ private List<String> fonts=new ArrayList<String>(); public Code(){ initFonts(); } private void initFonts(){ GraphicsEnvironment.getLocalGraphicsEnvironment().preferLocaleFonts(); String[] names=GraphicsEnvironment.getLocalGraphicsEnvironment().getAvailableFontFamilyNames(Locale.CHINA); for(String s:names){ char c=s.charAt(0); if(Character.isLowerCase(c)||Character.isUpperCase(c)){ }else{ fonts.add(s); } } } protected void processRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("image/jpeg;charset=UTF-8"); OutputStream out=response.getOutputStream(); BufferedImage bi=new BufferedImage(200,50,BufferedImage.TYPE_INT_RGB); Graphics2D g=bi.createGraphics(); char[] cs={'0','1','2','3','4','5','6','7','8','9'}; char[] use=new char[4]; g.setColor(new Color(240,240,240)); g.fillRect(0,0,200,50); for(int i=0;i<4;i++){ Point p=getPoint(i); int size=getSize(); use[i]=cs[(int)(Math.random()*cs.length)]; // g.setColor(new Color((int)(Math.random()*256),0,(int)(Math.random()*256))); g.setPaint(getPaint(p,size)); g.setFont(new Font(fonts.get((int)(Math.random()*fonts.size())),getFace(),size)); g.drawString(""+use[i],p.x,p.y); } g.setStroke(new BasicStroke(1.0f)); g.setPaint(null); for(int i=0;i<4;i++){ g.setColor(new Color((int)(Math.random()*0x00FFFFFFF))); g.drawLine((int)(Math.random()*200),(int)(Math.random()*50),(int)(Math.random()*200),(int)(Math.random()*50)); } Random random = new Random(); for (int i=0;i<88;i++) { int x = random.nextInt(200); int y = random.nextInt(50); g.setColor(new Color((int)(Math.random()*0x00FFFFFFF))); g.setStroke(getStroke()); g.drawLine(x,y,x,y); } ImageIO.write(bi,"JPEG",out); out.close(); g.dispose(); } private Stroke getStroke(){ BasicStroke bs=new BasicStroke((float)(Math.random()*3)); return bs; } private Point getPoint(int index){ return new Point(5+(index*((int)(Math.random()*10)+40)),40); } private Paint getPaint(Point p,int size){ GradientPaint gp=new GradientPaint(p.x,p.y,new Color((int)(Math.random()*256),0,(int)(Math.random()*256)), p.x,p.y-size,new Color((int)(Math.random()*256),(int)(Math.random()*256),(int)(Math.random()*256))); return gp; } private int getFace(){ if(Math.random()*10>5){ return Font.BOLD; }else{ return Font.ITALIC; } } private int getSize(){ int[] sizes=new int[20]; for(int i=0;i<20;i++){ sizes[i]=30+i; } return sizes[(int)(Math.random()*sizes.length)]; } // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code."> /** Handles the HTTP <code>GET</code> method. * @param request servlet request * @param response servlet response */ protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { processRequest(request, response); } /** Handles the HTTP <code>POST</code> method. * @param request servlet request * @param response servlet response */ protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { processRequest(request, response); } /** Returns a short description of the servlet. */ public String getServletInfo() { return "Short description"; } // </editor-fold> } 我們可以把它改成字母或者中文的驗證，道理都是一樣的，只不過在生成的時候，不一定用數字了，而是用所有可以輸入的文字.這樣，被程序識別的可能又小了.