【Java】登录操作中随机生成验证码的工具类

效果图：

工具类CreateImageCode.java：

import java.awt.Color;import java.awt.Font;import java.awt.Graphics;import java.awt.image.BufferedImage;import java.io.IOException;import java.io.OutputStream;import java.util.Random;import javax.imageio.ImageIO;public class CreateImageCode {private int width = 70;private int height = 27;private int codeCount = 4;// 干扰线数//private int lineCount = 10;// 验证码图片Buffer// 验证码private String code = null;public String getCode() {return code;}public void setCode(String code) {this.code = code;}private BufferedImage buffImg = null;Random random = new Random();public CreateImageCode() {createImage();}public CreateImageCode(int width, int height) {this.width = width;this.height = height;createImage();}public CreateImageCode(int width, int height, int codeCount) {this.width = width;this.height = height;this.codeCount = codeCount;createImage();}public CreateImageCode(int width, int height, int codeCount, int lineCount) {this.width = width;this.height = height;this.codeCount = codeCount;//this.lineCount = lineCount; createImage();}// 生成图片private void createImage() {int fontWidth = width / codeCount;// 字体宽度。int fontHeight = height - 5;// 字体高度。int codeY = height - 8;// 得到图片buffImg = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);Graphics g = buffImg.getGraphics();// 设置背景色g.setColor(getRandColor(249, 250));g.fillRect(0, 0, width, height);// 设置边框//g.setColor(getRandColor(200, 250));//g.drawRect(1, 1, width - 2, height - 2);// 设置字体Font font = new Font("Fixedsys", Font.PLAIN, fontHeight);g.setFont(font);/*// 设置干扰线for (int i = 0; i < lineCount; i++) {int x1 = random.nextInt(width);int y1 = random.nextInt(height);int x2 = random.nextInt(width);int y2 = random.nextInt(height);g.setColor(getRandColor(1, 255));g.drawLine(x1, y1, x2, y2);}*//*// 添加噪点float yawpRate = 0.01f;// 噪声率int area = (int) (yawpRate * width * height);for (int i = 0; i < area; i++) {int x = random.nextInt(width);int y = random.nextInt(height);buffImg.setRGB(x, y, random.nextInt(255));}*/String str1 = randomStr(codeCount);// 得到随机字符this.code = str1;for (int i = 0; i < codeCount; i++) {String strRand = str1.substring(i, i + 1);g.setColor(getRandColor(50, 250));// g.drawString(a,x,y);// a为要画出来的东西，x和y表示要画的东西最左侧字符的基线位于此图形上下文坐标系的 (x, y) 位置处g.drawString(strRand, i * fontWidth + 3, codeY);}}// 得到随机字符private String randomStr(int n) {String str1 = "1234567890";String str2 = "";int len = str1.length() - 1;double r;for (int i = 0; i < n; i++) {r = (Math.random()) * len;str2 = str2 + str1.charAt((int) r);}return str2;}// 得到随机颜色private Color getRandColor(int fc, int bc) {// 给定范围获得随机颜色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);}public void write(OutputStream sos) throws IOException {ImageIO.write(buffImg, "png", sos);sos.close();}}

在servlet中使用此工具类，输出验证码到网页：

package com.utils;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.io.IOException;@WebServlet(name = "GetImageCodeServlet",urlPatterns = {"/servlet/code.servlet"})public class GetImageCodeServlet extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request,response);}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {response.setContentType("image/jepg");// 控制浏览器不要缓存response.setDateHeader("expries", -1);response.setHeader("Cache-Control", "no-cache");response.setHeader("Pragma", "no-cache");// 创建图片CreateImageCode image = new CreateImageCode();String str = image.getCode();// 存入Session// System.out.println("验证码为"+str);request.getSession().setAttribute("code",str);// 输出到网页 image.write(response.getOutputStream());}}

JSP中在表单显示此图片（演示时不使用Ajax，直接将form提交到另一个servlet判断）：

<form action="${pageContext.request.contextPath}/servlet/codeTest.servlet"><input type="text" name="code"><img src="${pageContext.request.contextPath}/servlet/code.servlet"onclick="javascript:this.src='${pageContext.request.contextPath}/servlet/code.servlet?rm='+Math.random()"alt="获取验证码"><input type="submit" value="验证"></form>

后台验证验证码的servlet：

package com.utils;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.io.IOException;@WebServlet(name = "CodeTestServlet" ,urlPatterns = {"/servlet/codeTest.servlet"})public class CodeTestServlet extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doGet(request,response);}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {String code = request.getParameter("code");if (code.equals(request.getSession().getAttribute("code"))) {System.out.println("验证成功，验证码为：" + request.getSession().getAttribute("code"));// response.sendRedirect(getServletContext().getContextPath()+"/login.jsp");}else{System.out.println("验证失败");}}}

----

使用的是3.0的注解开发，web.xml中不需配置

若为maven项目，依赖为：

<dependency><groupId>javax.servlet</groupId><artifactId>javax.servlet-api</artifactId><version>3.1.0</version></dependency><dependency><groupId>javax.servlet.jsp</groupId><artifactId>javax.servlet.jsp-api</artifactId><version>2.3.1</version></dependency>