'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' };
/** * 初始化验证图片属性 */ public void init() throws ServletException {
/** * Package name : com.skcc.sample.action * File name : VerifyCodeServlet.java * Author : Administrator * Date : 2008-9-4 * Description : VerifyCodeServlet */ public class VerifyCodeServlet extends HttpServlet {
若要在jsp页面中使用这个验证码 只需用一个 <img src="那个servlet 的地址"
import java.awt.Color; import java.awt.Font; import java.awt.Graphics2D; import java.awt.image.BufferedImage; import java.util.Random;
// 将配置的信息转换成数值 try {
if (strWidth != null && strWidth.length() != 0) { width = Integer.parseInt(strWidth);
} if (strHeight != null && strHeight.length() != 0) {
int b = fc + random.nextInt(bc - fc); return new Color(r, g, b); } //Initialize global variables public void init() throws ServletException { } //Process the HTTP Get request public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //设置页面不缓存 response.setHeader("Pragma", "No-cache"); response.setHeader("Cache-Control", "no-cache"); response.setDateHeader("Expires", 0); // 在内存中创建图象 int width = 60, height = 20; BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); // 获取图形上下文 Graphics g = image.getGraphics(); //生成随机类 Random random = new Random(); // 设定背景色 g.setColor(getRandColor(200, 250)); g.fillRect(0, 0, width, height); //设定字体 g.setFont(new Font("Times New Roman", Font.PLAIN, 18)); //画边框
// 从web.xml中获取初始信息 // 宽度 String strWidth = this.getInitParameter("width"); // 高度 String strHeight = this.getInitParameter("height"); // 字符个数 String strCodeCount = this.getInitParameter("codeCount");
package com.banding.web.util; import java.awt.Color; import java.awt.Font; import java.awt.Graphics; import java.awt.image.BufferedImage; import java.io.IOException; import java.util.Random; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import com.sun.image.codec.jpeg.JPEGCodec; import com.sun.image.codec.jpeg.JPEGImageEncoder; public class Image extends HttpServlet { //public static final long serialVersionUID = 1L ; //private static final String CONTENT_TYPE = "text/html; charset=GBK"; public Color getRandColor(int fc, int bc) { //给定范围获 得随机颜色 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);
/** * 验证码图片的宽度。 */ private int width = 60;
/** * 验证码图片的高度。 */ private int height = 20;
/** * 验证码字符个数 */ private int codeCount = 4;
/** * xx */ private int xx = 0;
throws ServletException, java.io.IOException {
// 定义图像buffer BufferedImage buffImg = new BufferedImage(width, height,
g.dispose(); // 输出图象到页面 //ImageIO.write(image, "JPEG", response.getOutputStream()); JPEGImageEncoder encode = JPEGCodec.createJPEGEncoder(response. getOutputStream()); encode.encode(image); } //Clean up resources public void destroy() { } } 上面的代码可以直接用，在web.xml中配置好以后就可以在浏览器 中访问这个servlet，能得到下面的效果
import javax.imageio.ImageIO;
import javax.servlet.ServletException; import javax.servlet.ServletOutputStream; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession;
//g.setColor(new Color()); //g.drawRect(0,0,width-1,height-1); // 随机产生155条干扰线，使图象中的认证码不易被其它程序探 测到 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); } // 取随机产生的认证码(4位数字) String sRand = ""; for (int i = 0; i < 4; i++) { String rand = String.valueOf(random.nextInt(10)); sRand += rand; // 将认证码显示到图象中 g.setColor(new Color(20 + random.nextInt(110), 20 + random.nextInt(110), 20 + random.nextInt(110))); //调用函数出来的颜色相同，可能是因为种子太接近，所以只能 直接生成 g.drawString(rand, 13 * i + 6, 16); } // 将认证码存入SESSION request.getSession().setAttribute("rand", sRand); // 图象生效