第一步：编写图形验证码工具

package com.zhh.demo.common.util;import lombok.extern.slf4j.Slf4j;
import org.apache.tomcat.util.codec.binary.Base64;
import org.springframework.stereotype.Component;import javax.imageio.ImageIO;
import javax.servlet.http.HttpServletResponse;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.Random;/*** @Description: 图形验证码* @Author: zhaoheng* @CreateTime: 2022-12-09*/
@Slf4j
@Component
public class GraphValidateCode {//设置图片宽private int width = 70;//设置图片高度private int height = 30;//设置干扰线数量private int lineSize = 40;/** 随机产生数字和字母组合的字符串,字体只显示大写，去掉了1,0,i,o几个容易混淆的字符 */public static final String VERIFY_CODES = "23456789ABCDEFGHJKLMNPQRSTUVWXYZ";/*** 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) {Random random = new Random();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);}/*** 获取验证码** @return*/public String getIdentifyCode() {Random random = new Random();StringBuffer buffer = new StringBuffer();for (int i = 0; i < 4; i++) {char c = VERIFY_CODES.charAt(random.nextInt(VERIFY_CODES.length()));buffer.append(c);}return buffer.toString();}/*** 生成随机图片** @param identifyCode  图形码值* @return*/public BufferedImage getIdentifyImage(String identifyCode) {//BufferedImage类是具有缓冲区的Image类，Image类是用来描述图像信息的类BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_BGR);//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Graphics graphics = image.getGraphics();//图片大小graphics.fillRect(0, 0, width, height);//字体大小graphics.setFont(new Font("Times New Roman", Font.ROMAN_BASELINE, 20));//字体颜色graphics.setColor(getRandColor(110, 133));//绘制干扰线for (int i = 0; i <= lineSize; i++) {drawLine(graphics);}//绘制随机字符drawString(graphics, identifyCode);graphics.dispose();return image;}/*** 绘制字符串* @param g     产生Image对象的Graphics对象* @param identifyCode  图形码值*/private void drawString(Graphics g, String identifyCode) {Random random = new Random();for (int i = 0; i < identifyCode.length(); i++) {g.setFont(getFont());g.setColor(new Color(random.nextInt(101), random.nextInt(111), random.nextInt(121)));g.translate(random.nextInt(3), random.nextInt(3));// x:图形码值基于图片最左边的距离g.drawString(String.valueOf(identifyCode.charAt(i)), 13 * i + 8, 18);}}/*** 绘制干扰线*/private void drawLine(Graphics graphics) {Random random = new Random();int x = random.nextInt(width);int y = random.nextInt(height);int xl = random.nextInt(13);int yl = random.nextInt(15);graphics.drawLine(x, y, x + xl, y + yl);}/*** 响应验证码图片** @param identifyImg   图形码对象* @param response*/public void responseIdentifyImg(BufferedImage identifyImg, HttpServletResponse response) {//设置响应类型，告诉浏览器输出的内容是图片response.setContentType("image/jpeg");//设置响应头信息，告诉浏览器不用缓冲此内容response.setHeader("Pragma", "No-cache");response.setHeader("Cache-Control", "no-cache");response.setDateHeader("Expire", 0);try {//把内存中的图片通过流动形式输出到客户端ImageIO.write(identifyImg, "JPEG", response.getOutputStream());} catch (IOException e) {log.error("图形验证码输出错误", e);}}/*** BufferedImage转base64* @param img  BufferedImage 对象* @return*/public String getBase64FromImage(BufferedImage img) {String base64 = "";try (ByteArrayOutputStream stream = new ByteArrayOutputStream()) {// 设置图片的格式ImageIO.write(img, "jpg", stream);byte[] bytes = Base64.encodeBase64(stream.toByteArray());base64 = new String(bytes);} catch (IOException e) {log.error("图形验证码转base64错误", e);}return "data:image/jpeg;base64," + base64;}}

第二步：编写接口

两个接口，两种方式：1.接口直接返回图片。2.接口返回base64字符串。

@Api(tags = "验证码-api")
@RequestMapping("/api/test")
@RestController
public class TestController {// 模拟把验证码的值存储到缓存(记得添加过期时间)Map<String,String> hashMap = new HashMap<>();@Autowiredprivate GraphValidateCode graphValidateCode;/*** 给前端返回一个验证码图片* @return*/@ApiOperation("获取图形验证码")@GetMapping("/identifyImage")public void identifyImage(HttpServletResponse response,@ApiParam(value = "图形验证码id,无值：生成验证码，有值:刷新验证码")@RequestParam(name = "codeId", required = false) String codeId) {// 验证码String identifyCode = graphValidateCode.getIdentifyCode();// 模拟把验证码的值存储到缓存(记得添加过期时间)if (codeId == null) {System.out.println("获取图形码");codeId = ToolUtil.simpleUUID();// 保存图形码值hashMap.put(codeId, identifyCode);} else {System.out.println("刷新图形码");// 更新图形码值，此时此刻 图形码可能已经过期删除，那就相对于保存一个新的hashMap.put(codeId, identifyCode);}// 图形验证码对应的UUID放在header中，前端可以拿到response.setHeader("codeId", codeId);//根据验证码创建图片BufferedImage identifyImage = graphValidateCode.getIdentifyImage(identifyCode);//回传给前端graphValidateCode.responseIdentifyImg(identifyImage, response);}/*** 给前端返回一个验证码图片-base64格式* @return*/@ApiOperation("获取图形验证码-base64格式")@GetMapping("/identifyImage2")public String identifyImage2(@ApiParam(value = "图形验证码id,无值：生成验证码，有值:刷新验证码")@RequestParam(name = "codeId", required = false) String codeId) {String identifyCode = graphValidateCode.getIdentifyCode();// 模拟把验证码的值存储到缓存(记得添加过期时间)if (codeId == null) {System.out.println("获取图形码");codeId = ToolUtil.simpleUUID();// 保存图形码值hashMap.put(codeId, identifyCode);} else {System.out.println("刷新图形码");// 更新图形码值，此时此刻 图形码可能已经过期删除，那就相对于保存一个新的hashMap.put(codeId, identifyCode);}//根据验证码创建图片BufferedImage identifyImage = graphValidateCode.getIdentifyImage(identifyCode);//回传给前端System.out.println("新图形码值:" + identifyCode);return graphValidateCode.getBase64FromImage(identifyImage);}}