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以下是验证码动态生成范例。
/** vfcodeservlet.java */
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.*;
import javax.servlet.http.*;
public class vfcodeservlet extends HttpServlet {
private static final String CONTENT_TYPE = "text/html; charset=UTF-8";
public void init(ServletConfig config) throws ServletException {
super.init(config);
}
public void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException,
IOException {
response.setContentType(CONTENT_TYPE);
response.setContentType("image/jpeg");//设置相应类型,告诉浏览器输出的内容为图片
response.setHeader("Pragma", "No-cache");//设置响应头信息，告诉浏览器不要缓存此内容
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expire", 0);
RandomValidateCode randomValidateCode = new RandomValidateCode();
try {
randomValidateCode.getRandcode(request, response);//输出图片方法
} catch (Exception e) {
e.printStackTrace();
}
}
public void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException,
IOException {
doGet(request,response);
}
}
//生成验证码
package com.mgear.admin.login;
import java.awt.Graphics;
import java.awt.Color;
import java.awt.Font;
import java.awt.image.BufferedImage;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
public class RandomValidateCode {
public RandomValidateCode() {
super();
}
public static final String RANDOMCODEKEY =
"RANDOMVALIDATECODEKEY"; //放到session中的key
private Random random = new Random();
private String randString = "123456789ABCDEFGHJKLMNPQRSTUVWXYZ"; //随机产生的字符串
private int width = 80; //图片宽
private int height = 26; //图片高
private int lineSize = 40; //干扰线数量
private int stringNum = 4; //随机产生字符数量
/*
* 获得字体
*/
private Font getFont() {
return new Font("Fixedsys", Font.CENTER_BASELINE, 18);
}
/*
* 获得颜色
*/
private Color getRandColor(int fc, int bc) {
if (fc > 255)
fc = 255;
if (bc > 255)
bc = 255;
int r = fc + random.nextInt(bc - fc - 16);
int g = fc + random.nextInt(bc - fc - 14);
int b = fc + random.nextInt(bc - fc - 18);
return new Color(r, g, b);
}
/**
* 生成随机图片
*/
public void getRandcode(HttpServletRequest request,
HttpServletResponse response) {
HttpSession session = request.getSession();
//BufferedImage类是具有缓冲区的Image类,Image类是用于描述图像信息的类
BufferedImage image =
new BufferedImage(width, height, BufferedImage.TYPE_INT_BGR);
Graphics g =
image.getGraphics(); //产生Image对象的Graphics对象,改对象可以在图像上进行各种绘制操作
g.fillRect(0, 0, width, height);
g.setFont(new Font("Times New Roman", Font.ROMAN_BASELINE, 18));
g.setColor(getRandColor(110, 133));
//绘制干扰线
for (int i = 0; i <= lineSize; i++) {
drowLine(g);
}
//绘制随机字符
String randomString = "";
for (int i = 1; i <= stringNum; i++) {
randomString = drowString(g, randomString, i);
}
session.removeAttribute(RANDOMCODEKEY);
session.setAttribute(RANDOMCODEKEY, randomString);
System.out.println(randomString);
g.dispose();
try {
ImageIO.write(image, "JPEG",
response.getOutputStream()); //将内存中的图片通过流动形式输出到客户端
} catch (Exception e) {
e.printStackTrace();
}
}
/*
* 绘制字符串
*/
private String drowString(Graphics g, String randomString, int i) {
g.setFont(getFont());
g.setColor(new Color(random.nextInt(101), random.nextInt(111),
random.nextInt(121)));
String rand =
String.valueOf(getRandomString(random.nextInt(randString.length())));
randomString += rand;
g.translate(random.nextInt(3), random.nextInt(3));
g.drawString(rand, 13 * i, 16);
return randomString;
}
/*
* 绘制干扰线
*/
private void drowLine(Graphics g) {
int x = random.nextInt(width);
int y = random.nextInt(height);
int xl = random.nextInt(13);
int yl = random.nextInt(15);
g.drawLine(x, y, x + xl, y + yl);
}
/*
* 获取随机的字符
*/
public String getRandomString(int num) {
return String.valueOf(randString.charAt(num));
}
}
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Java技术网站 → 『 Java开发技术 』 → 『 Java Web开发技术专题 』 → 如何用Servlet动态生成验证码
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