Java驗證碼生成的方法是什么？動力節點小編來告訴大家。

導入工具類

工具類的使用只需要使用【outputVerifyImage()方法即可】

package com.zcl.util;

import javax.imageio.ImageIO;
import java.awt.*;
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;

/**
 * 生成驗證碼工具類
 */
public class CheckCodeUtil {
    public static final String VERIFY_CODES = "123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    private static Random random = new Random();
    /**
     * 輸出隨機驗證碼圖片流,并返回驗證碼值（一般傳入輸出流，響應response頁面端，Web項目用的較多）
     *
     * @param w 圖片寬度
     * @param h 圖片高度
     * @param os 輸出流
     * @param verifySize 數據長度
     * @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;
    }
    /**
     * 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) {
        // 未設定展示源的字碼，賦默認值大寫字母+數字
        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 (生成圖片形式，用的較少)
     *
     * @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;
    }
    /**
     * 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();
        //文件不存在
        if (!dir.exists()) {
            //創建
            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);
        // 創建顏色集合，使用java.awt包下的類
        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);
        // 設置邊框色
        g2.setColor(Color.GRAY);
        g2.fillRect(0, 0, w, h);
        Color c = getRandColor(200, 250);
        // 設置背景色
        g2.setColor(c);
        g2.fillRect(0, 2, w, h - 4);
        // 繪制干擾線
        Random random = new Random();
        // 設置線條的顏色
        g2.setColor(getRandColor(160, 200));
        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
        // 噪聲率
        float yawpRate = 0.05f;
        int area = (int) (yawpRate * w * h);
        for (int i = 0; i < area; i++) {
            int x = random.nextInt(w);
            int y = random.nextInt(h);
            // 獲取隨機顏色
            int rgb = getRandomIntColor();
            image.setRGB(x, y, rgb);
        }
        // 添加圖片扭曲
        shear(g2, w, h, c);
        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);
    }
    /**
     * 隨機顏色
     *
     * @param fc
     * @param bc
     * @return
     */
    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);
            }
        }
    }
}

使用案例

public static void main(String[] args) throws Exception {
        FileOutputStream oup = new FileOutputStream("d:yzm.jpng"); // 輸出驗證碼的圖片
        String s = CheckCodeUtil.outputVerifyImage(100, 50, oup, 4);
        System.out.println("輸出輸出驗證碼的內容："+s);
    }

驗證碼的作用：防止機器自動注冊和攻擊服務器

Web注冊頁面如何使用呢?

主要是講文件輸出流改為瀏覽器的字節輸出流替換就可以完成驗證碼的輸出瀏覽器中了，驗證碼通過訪問這個路徑就會生成驗證碼返回給瀏覽器

package com.zcl.web; /**
 * TODO:
 *
 * @author zcl
 * @date 2022/3/29 14:56
 */
import com.zcl.util.CheckCodeUtil;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.IOException;
/**
 * 驗證碼生成
 */
@WebServlet("/checkCodeServlet")
public class CheckCodeServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 字節輸出流
        ServletOutputStream oup = response.getOutputStream();
        String s = CheckCodeUtil.outputVerifyImage(100, 50, oup, 4);
        // 存儲到Session中
        HttpSession session = request.getSession();
        session.setAttribute("checkCodeGen",s);
    }
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }
}

驗證碼的校驗