验证码的生成代码
package com.web.servlet; import java.awt.Color; import java.awt.Font; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.image.BufferedImage; import java.io.BufferedReader; import java.io.FileReader; import java.io.IOException; import java.util.ArrayList; import java.util.List; import java.util.Random; import javax.imageio.ImageIO; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; /** * * 验证码生成程序 * 在需要显示验证码图片时,我们只需要将src制定为当前Servlet即可,例:<img src="/WEB16/CheckImgServlet"> */ public class CheckCodeImageServlet extends HttpServlet { // 集合中保存所有成语 private List<String> words = new ArrayList<String>(); @Override public void init() throws ServletException { // 初始化阶段,读取new_words.txt // web工程中读取 文件,必须使用绝对磁盘路径 String path = getServletContext().getRealPath("/WEB-INF/new_words.txt"); try { BufferedReader reader = new BufferedReader(new FileReader(path)); String line; while ((line = reader.readLine()) != null) { words.add(line); } reader.close(); } catch (IOException e) { e.printStackTrace(); } } public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // 禁止缓存 // response.setHeader("Cache-Control", "no-cache"); // response.setHeader("Pragma", "no-cache"); // response.setDateHeader("Expires", -1); int width = 120; int height = 30; // 步骤一 绘制一张内存中图片 BufferedImage bufferedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); // 步骤二 图片绘制背景颜色 ---通过绘图对象 Graphics graphics = bufferedImage.getGraphics();// 得到画图对象 --- 画笔 // 绘制任何图形之前 都必须指定一个颜色 graphics.setColor(getRandColor(200, 250)); graphics.fillRect(0, 0, width, height); // 步骤三 绘制边框 graphics.setColor(Color.WHITE); graphics.drawRect(0, 0, width - 1, height - 1); // 步骤四 四个随机数字 Graphics2D graphics2d = (Graphics2D) graphics; // 设置输出字体 graphics2d.setFont(new Font("宋体", Font.BOLD, 18)); Random random = new Random();// 生成随机数 int index = random.nextInt(words.size()); String word = words.get(index);// 获得成语 // 定义x坐标 int x = 10; for (int i = 0; i < word.length(); i++) { // 随机颜色 graphics2d.setColor(new Color(20 + random.nextInt(110), 20 + random .nextInt(110), 20 + random.nextInt(110))); // 旋转 -30 --- 30度 int jiaodu = random.nextInt(60) - 30; // 换算弧度 double theta = jiaodu * Math.PI / 180; // 获得字母数字 char c = word.charAt(i); // 将c 输出到图片 graphics2d.rotate(theta, x, 20); graphics2d.drawString(String.valueOf(c), x, 20); graphics2d.rotate(-theta, x, 20); x += 30; } // 将验证码内容保存session request.getSession().setAttribute("checkcode_session", word); // 步骤五 绘制干扰线 graphics.setColor(getRandColor(160, 200)); int x1; int x2; int y1; int y2; for (int i = 0; i < 30; i++) { x1 = random.nextInt(width); x2 = random.nextInt(12); y1 = random.nextInt(height); y2 = random.nextInt(12); graphics.drawLine(x1, y1, x1 + x2, x2 + y2); } // 将上面图片输出到浏览器 ImageIO graphics.dispose();// 释放资源 //将图片写到response.getOutputStream()中 ImageIO.write(bufferedImage, "jpg", response.getOutputStream()); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } /** * 取其某一范围的color * * @param fc * int 范围参数1 * @param bc * int 范围参数2 * @return Color */ private Color getRandColor(int fc, int bc) { // 取其随机颜色 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); int b = fc + random.nextInt(bc - fc); return new Color(r, g, b); } }
验证码所依赖的词库文件
文件名为new_words.txt,将词库文件保存在/WEB-INF下即可(也可改变相应代码,然后将改文件放到其他地方)
一唱一和 一呼百应 一干二净 一举两得 一落千丈 . . .
验证码图片的使用
在需要验证码图片时我们只需将img标签的src设置为该Servlet即可。
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>Insert title here</title> </head> <body> <img src="/CheckCodeImageServlet"> </body> </html>
扩展需求
实现点击验证码,刷新操作。
思路:为img标签绑定一个单击事件,在绑定的函数中让img标签src属性值改变即可,但也不能影响它正常访问验证码生成的Servlet。
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>Insert title here</title> </head> <script type="text/javascript"> //实现验证码的刷新 function changeCheckCodeImg(ele){ var str=ele.src; ele.src=str+"?"; } </script> <body> <img src="/Shop/CheckCodeImageServlet" onclick="changeCheckCodeImg(this)"> </body> </html>