先要有10个图片文件,文件名用它上面的数字+.jpg 随机产生几个数字,用这几个数字加上.jpg就可以了. 还有一点就是要把这几个数字的顺序要保存下来,将来做真正的验证. 例如: String s = ""; for (int i = 0 ; i < 4; i++) { s += (int)(Math.random()*9); } for (int i = 0 ; i < s.length(); i++) { loadImage(s.charAt(i) + ".jpg"); }
<%@ page contentType="image/jpeg" import="java.awt.*, java.awt.image.*,java.util.*,javax.imageio.*" %> <%! Color getRandColor(int fc,int bc){//random color Random random = new Random(); if(fc>255) fc=255; if(bc>255) bc=255; int r=fc+random.nextInt(bc-fc); int g=fc+random.nextInt(bc-fc); int b=fc+random.nextInt(bc-fc); return new Color(r,g,b); } %> <% //page no cache response.setHeader("Pragma","No-cache"); response.setHeader("Cache-Control","no-cache"); response.setDateHeader("Expires", 0);// create image in memory int width=60, height=20; BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);// get GraphicContext Graphics g = image.getGraphics(); Random random = new Random();// set background g.setColor(getRandColor(200,250)); g.fillRect(0, 0, width, height);//set font g.setFont(new Font("Times New Roman",Font.PLAIN,18));//set border //g.setColor(new Color()); //g.drawRect(0,0,width-1,height-1);// generate confusing lines g.setColor(getRandColor(160,200)); for (int i=0;i<155;i++) { int x = random.nextInt(width); int y = random.nextInt(height); int xl = random.nextInt(12); int yl = random.nextInt(12); g.drawLine(x,y,x+xl,y+yl); }// 4 bit random number String sRand=""; for (int i=0;i<4;i++){ String rand=String.valueOf(random.nextInt(10)); sRand+=rand; // put validation code to image g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110))); g.drawString(rand,13*i+6,16); }// save code to SESSION session.setAttribute("rand",sRand); g.dispose();// display image ImageIO.write(image, "JPEG", response.getOutputStream()); %>
随机产生几个数字,用这几个数字加上.jpg就可以了.
还有一点就是要把这几个数字的顺序要保存下来,将来做真正的验证.
例如:
String s = "";
for (int i = 0 ; i < 4; i++) {
s += (int)(Math.random()*9);
}
for (int i = 0 ; i < s.length(); i++) {
loadImage(s.charAt(i) + ".jpg");
}
java.awt.image.*,java.util.*,javax.imageio.*" %>
<%!
Color getRandColor(int fc,int bc){//random color
Random random = new Random();
if(fc>255) fc=255;
if(bc>255) bc=255;
int r=fc+random.nextInt(bc-fc);
int g=fc+random.nextInt(bc-fc);
int b=fc+random.nextInt(bc-fc);
return new Color(r,g,b);
}
%>
<%
//page no cache
response.setHeader("Pragma","No-cache");
response.setHeader("Cache-Control","no-cache");
response.setDateHeader("Expires", 0);// create image in memory
int width=60, height=20;
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);// get GraphicContext
Graphics g = image.getGraphics();
Random random = new Random();// set background
g.setColor(getRandColor(200,250));
g.fillRect(0, 0, width, height);//set font
g.setFont(new Font("Times New Roman",Font.PLAIN,18));//set border
//g.setColor(new Color());
//g.drawRect(0,0,width-1,height-1);// generate confusing lines
g.setColor(getRandColor(160,200));
for (int i=0;i<155;i++)
{
int x = random.nextInt(width);
int y = random.nextInt(height);
int xl = random.nextInt(12);
int yl = random.nextInt(12);
g.drawLine(x,y,x+xl,y+yl);
}// 4 bit random number
String sRand="";
for (int i=0;i<4;i++){
String rand=String.valueOf(random.nextInt(10));
sRand+=rand;
// put validation code to image
g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));
g.drawString(rand,13*i+6,16);
}// save code to SESSION
session.setAttribute("rand",sRand);
g.dispose();// display image
ImageIO.write(image, "JPEG", response.getOutputStream());
%>