生成验证码
/**
* 验证码工具类
*
* @name: VerificationCode
* @author: terwer
* @date: 2022-07-17 22:21
**/
public class VerificationCode {
private static final String[] randomStr = {"0", "1", "2", "3", "4",
"5", "6", "7", "8", "9", "A", "B",
"C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M",
"N", "O", "P", "Q", "R",
"S", "T", "U", "V", "W", "X", "Y", "Z"};
/**
* 随机生成验证码
*
* @return
*/
public static Map getVerificationCode() {
return getVerificationCodeWithStr(null);
}
/**
* 利用给定的字符串生成验证码
*
* @param str 指定的字符串
* @return
*/
public static Map getVerificationCodeWithStr(String str) {
// 设置默认生成 4个 长度的验证码
int strLength = 4;
char[] strArr = null;
if (StringUtils.isNotEmpty(str)) {
strLength = str.length();
strArr = str.toCharArray();
}
// 定义验证码图片大小
int width = 20 * strLength + 5, height = 25;
// 在内存中创建 图像
BufferedImage bufferedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
// 为内存中要创建的图像生成画布,
Graphics2D graphics2D = bufferedImage.createGraphics();
// 画一个白色矩形,作为验证码背景
graphics2D.setColor(Color.WHITE);
// 填充
graphics2D.fillRect(0, 0, width, height);
// 画 100 条 灰色的 随机干扰线
if (StringUtils.isNotEmpty(str)) {
graphics2D.setColor(Color.WHITE);
} else {
graphics2D.setColor(Color.GRAY);
}
Random random = new Random();
for (int i = 0; i < 100; i++) {
graphics2D.drawLine(random.nextInt(width), random.nextInt(height), random.nextInt(width), random.nextInt(height));
}
// 创建字体
Font font = new Font("Times New Roman", Font.BOLD, 25);
graphics2D.setFont(font);
StringBuffer sb = new StringBuffer();
// 取得 4 位数的 随机字符串
for (int i = 0; i < strLength; i++) {
// 返回一个 随机数,在 1 和 20 之间
String randomNumber = randomStr[random.nextInt(36)];
if (StringUtils.isNotEmpty(str)) {
randomNumber = String.valueOf(strArr[i]);
}
int red = random.nextInt(255);
int green = random.nextInt(255);
int blue = random.nextInt(255);
//获得一个随机红蓝绿的配合颜色
graphics2D.setColor(new Color(red, green, blue));
//把该数字用画笔在画布画出,并指定数字的坐标
if (null != randomNumber) {
graphics2D.drawString(randomNumber, 20 * i + 5, (height / 2) + 10);
//把该数字加到缓存字符串中。用于等会生成验证码字符串set到session中用于校对
sb.append(randomNumber);
}
}
// 清除内存的图片
bufferedImage.flush();
// 释放资源
graphics2D.dispose();
// 返回结果
Map result = new HashMap();
result.put("imgStream", bufferedImage);
result.put("code", str);
return result;
}
}
解决 alpine 镜像运行 springboot 无法获取验证码(缺少字体)的问题
问题
Caused by: java.lang.NullPointerException
at sun.awt.FontConfiguration.getVersion(FontConfiguration.java:1264)
at sun.awt.FontConfiguration.readFontConfigFile(FontConfiguration.java:219)
at sun.awt.FontConfiguration.init(FontConfiguration.java:107)
at sun.awt.X11FontManager.createFontConfiguration(X11FontManager.java:774)
at sun.font.SunFontManager$2.run(SunFontManager.java:431)
at java.security.AccessController.doPrivileged(Native Method)
at sun.font.SunFontManager.<init>(SunFontManager.java:376)
at sun.awt.FcFontManager.<init>(FcFontManager.java:35)
at sun.awt.X11FontManager.<init>(X11FontManager.java:57)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
方案
FROM maven:3.6.0-jdk-8-alpine
ENV LANG en_US.UTF-8
RUN apk add --update ttf-dejavu fontconfig && rm -rf /var/cache/apk/*
参考
https://www.cnblogs.com/oukele/p/12869137.html
标签:graphics2D,java,sun,random,验证码,生成,nextInt,Java From: https://www.cnblogs.com/tangyouwei/p/java-generate-verification-code-picture-z1it1vl.html