一、環境準備

• idea
• java 1.8
• maven 3.6.3
• 操作系統：window10
• vue.min.js
• axios.min.js

二、VerifyCodeUtils工具類

import java.awt.Color; import java.awt.Font; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.RenderingHints; import java.awt.geom.AffineTransform; import java.awt.image.BufferedImage; import java.io.File; import java.io.FileOutputStream; import java.io.IOException; import java.io.OutputStream; import java.util.Arrays; import java.util.Random;import javax.imageio.ImageIO;/*** 生成驗證碼圖片的工具類**/ public class VerifyCodeUtils {// 使用到Algerian字體，系統里沒有的話需要安裝字體，字體只顯示大寫，去掉了1,0,i,o幾個容易混淆的字符public static final String VERIFY_CODES = "23456789ABCDEFGHJKLMNPQRSTUVWXYZ";private static Random random = new Random();/*** 使用系統默認字符源生成驗證碼** @param verifySize 驗證碼長度* @return*/public static String generateVerifyCode(int verifySize) {return generateVerifyCode(verifySize, VERIFY_CODES);}/*** 使用指定源生成驗證碼** @param verifySize 驗證碼長度* @param sources 驗證碼字符源* @return*/public static String generateVerifyCode(int verifySize, String sources) {if (sources == null || sources.length() == 0) {sources = VERIFY_CODES;}int codesLen = sources.length();Random rand = new Random(System.currentTimeMillis());StringBuilder verifyCode = new StringBuilder(verifySize);for (int i = 0; i < verifySize; i++) {verifyCode.append(sources.charAt(rand.nextInt(codesLen - 1)));}return verifyCode.toString();}/*** 生成隨機驗證碼文件,并返回驗證碼值** @param w* @param h* @param outputFile* @param verifySize* @return* @throws IOException*/public static String outputVerifyImage(int w, int h, File outputFile, int verifySize) throws IOException {String verifyCode = generateVerifyCode(verifySize);outputImage(w, h, outputFile, verifyCode);return verifyCode;}/*** 輸出隨機驗證碼圖片流,并返回驗證碼值** @param w* @param h* @param os* @param verifySize* @return* @throws IOException*/public static String outputVerifyImage(int w, int h, OutputStream os, int verifySize) throws IOException {String verifyCode = generateVerifyCode(verifySize);outputImage(w, h, os, verifyCode);return verifyCode;}/*** 生成指定驗證碼圖像文件** @param w* @param h* @param outputFile* @param code* @throws IOException*/public static void outputImage(int w, int h, File outputFile, String code) throws IOException {if (outputFile == null) {return;}File dir = outputFile.getParentFile();if (!dir.exists()) {dir.mkdirs();}try {outputFile.createNewFile();FileOutputStream fos = new FileOutputStream(outputFile);outputImage(w, h, fos, code);fos.close();} catch (IOException e) {throw e;}}/*** 輸出指定驗證碼圖片流** @param w* @param h* @param os* @param code* @throws IOException*/public static void outputImage(int w, int h, OutputStream os, String code) throws IOException {int verifySize = code.length();BufferedImage image = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);Random rand = new Random();Graphics2D g2 = image.createGraphics();g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);Color[] colors = new Color[5];Color[] colorSpaces = new Color[] { Color.WHITE, Color.CYAN, Color.GRAY, Color.LIGHT_GRAY, Color.MAGENTA,Color.ORANGE, Color.PINK, Color.YELLOW };float[] fractions = new float[colors.length];for (int i = 0; i < colors.length; i++) {colors[i] = colorSpaces[rand.nextInt(colorSpaces.length)];fractions[i] = rand.nextFloat();}Arrays.sort(fractions);g2.setColor(Color.GRAY);// 設置邊框色g2.fillRect(0, 0, w, h);Color c = getRandColor(200, 250);g2.setColor(c);// 設置背景色g2.fillRect(0, 2, w, h - 4);// 繪制干擾線Random random = new Random();g2.setColor(getRandColor(160, 200));// 設置線條的顏色for (int i = 0; i < 20; i++) {int x = random.nextInt(w - 1);int y = random.nextInt(h - 1);int xl = random.nextInt(6) + 1;int yl = random.nextInt(12) + 1;g2.drawLine(x, y, x + xl + 40, y + yl + 20);}// 添加噪點float yawpRate = 0.05f;// 噪聲率int area = (int) (yawpRate * w * h);for (int i = 0; i < area; i++) {int x = random.nextInt(w);int y = random.nextInt(h);int rgb = getRandomIntColor();image.setRGB(x, y, rgb);}shear(g2, w, h, c);// 使圖片扭曲g2.setColor(getRandColor(100, 160));int fontSize = h - 4;Font font = new Font("Algerian", Font.ITALIC, fontSize);g2.setFont(font);char[] chars = code.toCharArray();for (int i = 0; i < verifySize; i++) {AffineTransform affine = new AffineTransform();affine.setToRotation(Math.PI / 4 * rand.nextDouble() * (rand.nextBoolean() ? 1 : -1),(w / verifySize) * i + fontSize / 2, h / 2);g2.setTransform(affine);g2.drawChars(chars, i, 1, ((w - 10) / verifySize) * i + 5, h / 2 + fontSize / 2 - 10);}g2.dispose();ImageIO.write(image, "jpg", os);}private static Color getRandColor(int fc, int bc) {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);}private static int getRandomIntColor() {int[] rgb = getRandomRgb();int color = 0;for (int c : rgb) {color = color << 8;color = color | c;}return color;}private static int[] getRandomRgb() {int[] rgb = new int[3];for (int i = 0; i < 3; i++) {rgb[i] = random.nextInt(255);}return rgb;}private static void shear(Graphics g, int w1, int h1, Color color) {shearX(g, w1, h1, color);shearY(g, w1, h1, color);}private static void shearX(Graphics g, int w1, int h1, Color color) {int period = random.nextInt(2);boolean borderGap = true;int frames = 1;int phase = random.nextInt(2);for (int i = 0; i < h1; i++) {double d = (double) (period >> 1)* Math.sin((double) i / (double) period + (6.2831853071795862D * (double) phase) / (double) frames);g.copyArea(0, i, w1, 1, (int) d, 0);if (borderGap) {g.setColor(color);g.drawLine((int) d, i, 0, i);g.drawLine((int) d + w1, i, w1, i);}}}private static void shearY(Graphics g, int w1, int h1, Color color) {int period = random.nextInt(40) + 10; // 50;boolean borderGap = true;int frames = 20;int phase = 7;for (int i = 0; i < w1; i++) {double d = (double) (period >> 1)* Math.sin((double) i / (double) period + (6.2831853071795862D * (double) phase) / (double) frames);g.copyArea(i, 0, 1, h1, 0, (int) d);if (borderGap) {g.setColor(color);g.drawLine(i, (int) d, i, 0);g.drawLine(i, (int) d + h1, i, h1);}}}//生成一張驗證碼圖片，并保存到項目的verifyCodeImg文件夾下@SuppressWarnings("finally")public static String createOneCodeImage(){String imgName = "";try {File dir = new File("./verifyCodeImg");int w = 95, h = 50;String verifyCode = generateVerifyCode(4);File file = new File(dir, verifyCode + ".jpg");outputImage(w, h, file, verifyCode);imgName = verifyCode;} catch (IOException e) {imgName = "";e.printStackTrace();}finally{return imgName;}}public static void main(String[] args) throws IOException {String codeImage = VerifyCodeUtils.createOneCodeImage();System.out.println(codeImage);}}

三、實現功能

Controller

/*** @作者 suya* @時間 2020/12/11* @描述 用戶控制器*/ @RestController @CrossOrigin //允許跨域 @RequestMapping(path = "/user") public class UserController {/*** 生成驗證碼圖片*/@GetMapping("getImage")public String getImageCode(HttpServletRequest request)throws IOException{// 1.使用工具類生成驗證碼String code = VerifyCodeUtils.generateVerifyCode(4);// 2.將驗證碼放入servletContext作用域request.getServletContext().setAttribute("code",code);// 3.將圖片轉為字節數組輸出流ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();VerifyCodeUtils.outputImage(220,60,byteArrayOutputStream,code);// 4.將字節數組輸出流編碼為base64返回return "data:image/png;base64," + Base64Utils.encodeToString(byteArrayOutputStream.toByteArray());} }

百度百科：
base64：Base64是網絡上最常見的用于傳輸8Bit字節碼的編碼方式之一，Base64就是一種基于64個可打印字符來表示二進制數據的方法。
字節碼：包含執行程序，由一序列 op 代碼/數據對組成的二進制文件，是一種中間碼。

我們知道，計算機之間是通過二進制數據來進行通信的。base64就是其中一種通信的規范，用64個可打印字符來代表八Bit(位)的二進制程序文件的方法。

那我們應該怎么來在img中表示它呢？
詳細見該文章
我們這里用：data:image/png;base64,+base64

vue

html

<img id="num" :src="url" alt=""> <a href="javascript:;" @click="getImg()">換一張</a>

axios

<script> <!-- 創建vue實例-->var app = new Vue({// 管理#wrap標簽內的內容el:"#wrap",// 數據存放位置data:{url:"",},methods:{// 通過axios獲取圖片信息方法getImg(){// 設置_this為當前vue實例var _this = this;// axios負責vue與springboot交互// axios異步發送請求獲取后臺傳遞數據axios.get("http://localhost:8081/emp_vue/user/getImage?time="+Math.random()).then(res=>{_this.url = res.data;})}},// 頁面初始化回調函數created(){this.getImg();}}); </script>

這里用到axios http庫進行前后端交互。

四、效果圖

五、結語

莫要書山有路勤為徑，學海無涯苦作舟
而應日積月累，樂在其中

希望能幫助到您

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