<%! 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));
// 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 随即写出4个数字 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 传递图片中的数字 session.setAttribute("rand",sRand);
import javax.swing.JFrame;
import javax.swing.JLabel;
import java.awt.BorderLayout;
import java.awt.image.BufferedImage;
import java.io.*;
import java.awt.Toolkit;
import java.awt.Dimension;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.Graphics;
import java.awt.Color;
import javax.swing.ImageIcon;
public class frame extends JFrame {
JButton btnok = new JButton("生成图片");
JPanel contentpane = new JPanel();
JLabel label = new JLabel(); public frame() {
try {
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setContentPane(contentpane);
this.setResizable(false);
this.setTitle("Test");
this.setSize(300, 300);
Dimension screen = Toolkit.getDefaultToolkit().getScreenSize();
Dimension size = this.getSize(); this.setLocation((screen.width - size.width) / 2,
(screen.height - size.height) / 2); this.setLayout(new BorderLayout());
this.add(btnok, BorderLayout.SOUTH);
this.add(label, BorderLayout.CENTER); btnok.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
try {
BufferedReader reader = new BufferedReader(new
FileReader(new File("d:\\1.txt")));
String str = reader.readLine();
reader.close(); BufferedImage image = new BufferedImage((int) label.
getSize().getWidth(),
(int) label.getSize().getHeight(),
BufferedImage.TYPE_INT_RGB);
Graphics gr = image.getGraphics();
gr.setColor(Color.red);
gr.drawString(str, 100, 100);
gr.dispose();
label.setIcon(new ImageIcon(image));
} catch (Exception ex) {
ex.printStackTrace();
}
}
});
this.setVisible(true);
} catch (Exception ex) {
ex.printStackTrace();
}
} public static void main(String[] args) {
new frame();
}
}
你可以得到一幅图象吗?
如:xxx.tif 保存在一个目录下,如:d:\\xxx.tif
<%@ page language="java" import="java.util.*" pageEncoding="GBK"%>
<%@ page contentType="image/jpeg" import="java.awt.*,
java.awt.image.*,javax.imageio.*,java.net.*" %>
<%!
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 随即写出4个数字
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 传递图片中的数字
session.setAttribute("rand",sRand);
g.dispose();
// display image
ImageIO.write(image, "JPEG", response.getOutputStream());
out.clear();
out = pageContext.pushBody();
%>
Login.jsp<tr>
<td>
验证码:
</td>
<td>
<html:text property="image"></html:text>
</td>
<td>
<img width="60" height="20" src="<%=basePath%>/image.jsp">
</td>
</tr>
loginAction
String validatecode=(String)session.getAttribute("rand");
//获取image.jsp中传递的数字值
String inputcode=logonForm.getImage();
//从login.jsp中获取文本框输入的值
if(validatecode.equals(inputcode)){ //如果两个相等
登陆
}else
{
String error="验证码错误,请重新输入.....";
request.setAttribute("error", error);
return mapping.findForward("fail");
}