验证码图片生成工具类——Captcha.java
验证码图片生成工具,使用JAVA生成的图片验证码,调用getRandcode方法获取图片验证码,以流的方式传输到前端页面。
源码如下:(点击下载 Captcha.java)
import java.awt.Color; import java.awt.Font; import java.awt.Graphics; 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; /** * 验证码图片生成工具 * 使用JAVA生成的图片验证码,调用getRandcode方法获取图片验证码,以流的方式传输到前端页面。 * * * 作者: zhoubang * 日期:2015年8月7日 上午10:41:05 */ public class Captcha { public static final String RANDOMCODEKEY = "sess_captcha";// 放到session中的key private Random random = new Random(); private String randString = "0123456789";// 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); } /* * 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)); } /** * 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); 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(); } } }
简单使用方法(可自行设计,此方法为servlet调用):
import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; @WebServlet(description = "图片验证码生成", urlPatterns = { "/ImageServlet" }) public class ImageServlet extends HttpServlet { private static final long serialVersionUID = 1L; public ImageServlet() { super(); } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 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); Captcha randomValidateCode = new Captcha(); try { randomValidateCode.getRandcode(request, response);// 输出图片方法 } catch (Exception e) { e.printStackTrace(); } } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }
不定期会发布一些实用的Java开发文章