动态生成验证码案例

servlet代码

package cn.guizimo.web.servlet;

import javax.imageio.ImageIO;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import java.awt.*;

import java.awt.image.BufferedImage;

import java.io.IOException;

import java.util.Random;

@WebServlet("/checkCode")

public class CheckCode extends HttpServlet {

@Override

protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

int width = 100;

int height = 50;

//创建图片对象

BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_BGR);

//美化

Graphics g = image.getGraphics();

//背景

g.setColor(Color.PINK);

g.fillRect(0, 0, width, height);

//边框

g.setColor(Color.BLUE);

g.drawRect(0, 0, width - 1, height - 1);

String str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";

Random ran = new Random();

for (int i = 1; i

int index = ran.nextInt(str.length());

char ch = str.charAt(index);

g.drawString(ch+"",width/5*i,height/2);

}

//干扰线

g.setColor(Color.GREEN);

for (int i = 0; i < 10; i++) {

int x1 = ran.nextInt(width);

int x2= ran.nextInt(width);

int y1 = ran.nextInt(height);

int y2 = ran.nextInt(height);

g.drawLine(x1,y1,x2,y2);

}

//输出图片到浏览器

ImageIO.write(image, "jpg", resp.getOutputStream());

}

@Override

protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

this.doPost(req, resp);

}

}

html

window.onload = function () {

var img = document.getElementById("checkCode");

img.onclick = function () {

var data = new Date().getTime();

img.src = "/tomcat_test_war_exploded/checkCode?" + data;

}

}

启动项目

点击图片可以切换验证码