Java驗(yàn)證碼生成的方法是什么？動(dòng)力節(jié)點(diǎn)小編來告訴大家。

導(dǎo)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(yàn)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(jī)驗(yàn)證碼圖片流,并返回驗(yàn)證碼值（一般傳入輸出流，響應(yīng)response頁(yè)面端，Web項(xiàng)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(shù)據(jù)長(zhǎng)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(tǒng)默認(rèn)字符源生成驗(yàn)證碼
     *
     * @param verifySize 驗(yàn)證碼長(zhǎng)度
     * @return
     */
    public static String generateVerifyCode(int verifySize) {
        return generateVerifyCode(verifySize, VERIFY_CODES);
    }
    /**
     * 使用指定源生成驗(yàn)證碼
     *
     * @param verifySize 驗(yàn)證碼長(zhǎng)度
     * @param sources    驗(yàn)證碼字符源
     * @return
     */
    public static String generateVerifyCode(int verifySize, String sources) {
        // 未設(shè)定展示源的字碼，賦默認(rèn)值大寫字母+數(shù)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(jī)驗(yàn)證碼文件,并返回驗(yàn)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(yàn)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(chuàng)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(yàn)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(chuàng)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(shè)置邊框色
        g2.setColor(Color.GRAY);
        g2.fillRect(0, 0, w, h);
        Color c = getRandColor(200, 250);
        // 設(shè)置背景色
        g2.setColor(c);
        g2.fillRect(0, 2, w, h - 4);
        // 繪制干擾線
        Random random = new Random();
        // 設(shè)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(diǎn)
        // 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(jī)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(jī)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(yàn)證碼的圖片
        String s = CheckCodeUtil.outputVerifyImage(100, 50, oup, 4);
        System.out.println("輸出輸出驗(yàn)證碼的內(nèi)容："+s);
    }

驗(yàn)證碼的作用：防止機(jī)器自動(dòng)注冊(cè)和攻擊服務(wù)器

Web注冊(cè)頁(yè)面如何使用呢?

主要是講文件輸出流改為瀏覽器的字節(jié)輸出流替換就可以完成驗(yàn)證碼的輸出瀏覽器中了，驗(yàn)證碼通過訪問這個(gè)路徑就會(huì)生成驗(yàn)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(yàn)證碼生成
 */
@WebServlet("/checkCodeServlet")
public class CheckCodeServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 字節(jié)輸出流
        ServletOutputStream oup = response.getOutputStream();
        String s = CheckCodeUtil.outputVerifyImage(100, 50, oup, 4);
        // 存儲(chǔ)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(yàn)證碼的校驗(yàn)