本文分享一套使用 Java 實現的仿 QQ 風格圖片驗證碼生成工具類。該驗證碼具備以下特性：
註：原計劃實現字符扭曲，但因技術限制暫未完成，歡迎高手優化。
AuthImage繼承 HttpServlet，處理驗證碼圖片生成請求，將驗證碼存入 Session。
package hh.com.util;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
public class AuthImage extends javax.servlet.http.HttpServlet implements javax.servlet.Servlet {
static final long serialVersionUID = 1L;
public void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// 禁止緩存
response.setHeader("Pragma", "No-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
response.setContentType("image/jpeg");
// 生成 4 位隨機驗證碼
String verifyCode = VerifyCodeUtils.generateVerifyCode(4);
// 存入 Session
HttpSession session = request.getSession(true);
session.setAttribute("rand", verifyCode.toLowerCase());
// 輸出圖片流
int w = 200, h = 80;
VerifyCodeUtils.outputImage(w, h, response.getOutputStream(), verifyCode);
}
}
VerifyCodeUtils 核心實現包含驗證碼字符源定義、隨機生成、圖片繪製（幹擾線、噪點、扭曲、字符繪製）等完整邏輯。
package hh.com.util;
import java.awt.*;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.io.*;
import java.util.Arrays;
import java.util.Random;
import javax.imageio.ImageIO;
public class VerifyCodeUtils {
// 字符源（去除易混淆字符 1,0,i,o）
public static final String VERIFY_CODES = "23456789ABCDEFGHJKLMNPQRSTUVWXYZ";
private static Random random = new Random();
// 生成驗證碼字符串
public static String generateVerifyCode(int verifySize) { ... }
public static String generateVerifyCode(int verifySize, String sources) { ... }
// 輸出圖片到文件/流
public static String outputVerifyImage(int w, int h, File outputFile, int verifySize) throws IOException { ... }
public static String outputVerifyImage(int w, int h, OutputStream os, int verifySize) throws IOException { ... }
public static void outputImage(int w, int h, File outputFile, String code) throws IOException { ... }
// 核心圖片繪製邏輯
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);
Graphics2D g2 = image.createGraphics();
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
// 隨機漸變背景
Color[] colors = new Color[5];
Color[] colorSpaces = { 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[random.nextInt(colorSpaces.length)];
fractions[i] = random.nextFloat();
}
Arrays.sort(fractions);
// 邊框與背景
g2.setColor(Color.GRAY);
g2.fillRect(0, 0, w, h);
Color c = getRandColor(200, 250);
g2.setColor(c);
g2.fillRect(0, 2, w, h - 4);
// 繪製幹擾線
g2.setColor(getRandColor(160, 200));
for (int i = 0; i < 20; i++) {
int x = random.nextInt(w - 1), y = random.nextInt(h - 1);
int xl = random.nextInt(6) + 1, yl = random.nextInt(12) + 1;
g2.drawLine(x, y, x + xl + 40, y + yl + 20);
}
// 添加噪點
float yawpRate = 0.05f;
int area = (int) (yawpRate * w * h);
for (int i = 0; i < area; i++) {
int x = random.nextInt(w), y = random.nextInt(h);
image.setRGB(x, y, getRandomIntColor());
}
// 背景扭曲
shear(g2, w, h, c);
// 繪製驗證碼字符（隨機旋傾斜）
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 * random.nextDouble() * (random.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);
}
// 輔助方法：隨機顏色、扭曲算法、主方法測試等
private static Color getRandColor(int fc, int bc) { ... }
private static int getRandomIntColor() { ... }
private static int[] getRandomRgb() { ... }
private static void shear(Graphics g, int w1, int h1, Color color) { ... }
private static void shearX(Graphics g, int w1, int h1, Color color) { ... }
private static void shearY(Graphics g, int w1, int h1, Color color) { ... }
public static void main(String[] args) throws IOException { ... }
}
web.xml Servlet 映射配置<servlet>
<servlet-name>AuthImage</servlet-name>
<servlet-class>hh.com.util.AuthImage</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>AuthImage</servlet-name>
<url-pattern>/authImage</url-pattern>
</servlet-mapping>
AuthImage 和 VerifyCodeUtils 放入項目對應包路徑。web.xml 中配置 Servlet 映射。<img src="/authImage" /> 請求驗證碼圖片。rand 屬性與用戶輸入比對（忽略大小寫）。生成的驗證碼圖片具有隨機背景、傾斜字符、幹擾線及噪點，視覺風格酷似 QQ 登錄驗證碼，有效防止機器識別。
