SpringBoot实现Thymeleaf验证码生成

使用后台返回验证码图片，验证码存到session中后端实现校验，前端只展示验证码图片。

本篇用SpringBoot Thymeleaf实现验证码生成。

创建springboot项目 引入依赖

完整pom.xml

<?xml version='1.0' encoding='UTF-8'?><project xmlns='http://maven.apache.org/POM/4.0.0' xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' xsi:schemaLocation='http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd'> <modelVersion>4.0.0</modelVersion> <parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>2.2.6.RELEASE</version><relativePath/> <!-- lookup parent from repository --> </parent> <groupId>com.example</groupId> <artifactId>web</artifactId> <version>0.0.1-SNAPSHOT</version> <name>web</name> <description>Demo project for Spring Boot</description> <properties><java.version>1.8</java.version> </properties> <dependencies><dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId></dependency><dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> <exclusions><exclusion> <groupId>org.junit.vintage</groupId> <artifactId>junit-vintage-engine</artifactId></exclusion> </exclusions></dependency><!-- ThymeLeaf 依赖 --><dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-thymeleaf</artifactId></dependency> </dependencies> <build><plugins> <plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId> </plugin></plugins> </build></project>

application.yml配置 Thymeleaf

#Thymeleaf配置spring: mvc: static-path-pattern: /** thymeleaf: mode: HTML encoding: UTF-8 #关闭缓存 cache: false

创建CaptchaController.java 类

package com.example.web.controller;import com.example.web.util.VerifyCode;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RestController;import javax.imageio.ImageIO;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import java.awt.image.BufferedImage;import java.io.IOException;import java.io.OutputStream;@RestControllerpublic class CaptchaController { /* 获取验证码图片*/ @RequestMapping('/getVerifyCode') public void getVerificationCode(HttpServletResponse response, HttpServletRequest request) {try { int width = 200; int height = 69; BufferedImage verifyImg = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);//生成对应宽高的初始图片 String randomText = VerifyCode.drawRandomText(width, height, verifyImg);//单独的一个类方法，出于代码复用考虑，进行了封装。功能是生成验证码字符并加上噪点，干扰线，返回值为验证码字符 request.getSession().setAttribute('verifyCode', randomText); response.setContentType('image/png');//必须设置响应内容类型为图片，否则前台不识别 OutputStream os = response.getOutputStream(); //获取文件输出流 ImageIO.write(verifyImg, 'png', os);//输出图片流 os.flush(); os.close();//关闭流} catch (IOException e) { e.printStackTrace();} }}

创建VerifyCode.java 工具类

package com.example.web.util;import java.awt.*;import java.awt.image.BufferedImage;import java.util.Random;public class VerifyCode { public static String drawRandomText(int width, int height, BufferedImage verifyImg) {Graphics2D graphics = (Graphics2D) verifyImg.getGraphics();graphics.setColor(Color.WHITE);//设置画笔颜色-验证码背景色graphics.fillRect(0, 0, width, height);//填充背景graphics.setFont(new Font('微软雅黑', Font.BOLD, 40));//数字和字母的组合String baseNumLetter = '123456789abcdefghijklmnopqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ';StringBuilder builder = new StringBuilder();int x = 10; //旋转原点的 x 坐标String ch;Random random = new Random();for (int i = 0; i < 4; i++) { graphics.setColor(getRandomColor()); //设置字体旋转角度 int degree = random.nextInt() % 30; //角度小于30度 int dot = random.nextInt(baseNumLetter.length()); ch = baseNumLetter.charAt(dot) + ''; builder.append(ch); //正向旋转 graphics.rotate(degree * Math.PI / 180, x, 45); graphics.drawString(ch, x, 45); //反向旋转 graphics.rotate(-degree * Math.PI / 180, x, 45); x += 48;}//画干扰线for (int i = 0; i < 6; i++) { // 设置随机颜色 graphics.setColor(getRandomColor()); // 随机画线 graphics.drawLine(random.nextInt(width), random.nextInt(height), random.nextInt(width), random.nextInt(height));}//添加噪点for (int i = 0; i < 30; i++) { int x1 = random.nextInt(width); int y1 = random.nextInt(height); graphics.setColor(getRandomColor()); graphics.fillRect(x1, y1, 2, 2);}return builder.toString(); } /** * 随机取色 */ private static Color getRandomColor() {Random ran = new Random();return new Color(ran.nextInt(256),ran.nextInt(256), ran.nextInt(256)); }}

创建UserController.java 类

package com.example.web.controller;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.RequestMapping;@Controllerpublic class UserController { @RequestMapping('/login') public String login() {return 'login'; }}

resources/templates目录下创建login.html

<!DOCTYPE html><html lang='en' xmlns:th='http://www.thymeleaf.org'><head> <meta charset='UTF-8'> <title>Show User</title></head><body><a href='javascript:void(0);' rel='external nofollow'> <img th:src='https://www.haobala.com/bcjs/@{getVerifyCode}' onclick='changeCode()' /></a></body><!-- 引入JQuery --><script src='https://www.haobala.com/static/js/jquery.min.js' th:src='https://www.haobala.com/bcjs/@{/js/jquery.min.js}'></script><script> function changeCode() {const src = 'https://www.haobala.com/getVerifyCode?' + new Date().getTime(); //加时间戳，防止浏览器利用缓存$(’.verifyCode’).attr('src', src); }</script></html>

启动项目访问http://localhost:8080/login

点击图片可以更换验证码，至于后面的后台验证就不讲了。参考文章后台java 实现验证码生成

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