java如何生成登录随机验证码

本文实例为大家分享了java生成登录随机验证码的具体代码，供大家参考，具体内容如下

验证码工具类： VerifyUtil.java

import java.awt.*;
import java.awt.image.BufferedImage;
import java.util.HashMap;
import java.util.Map;
import java.util.Random;

public class VerifyUtil {
  // 验证码字符集
  private static final char[] CHARS = {
      '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',
      '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'};
  // 字符数量
  private static final int SIZE = 4;
  // 干扰线数量
  private static final int LINES = 5;
  // 宽度
  private static final int WIDTH = 80;
  // 高度
  private static final int HEIGHT = 40;
  // 字体大小
  private static final int FONT_SIZE = 30;

  /**
   * 生成随机验证码及图片
   */
  public static Map<String, Object> createImage() {
    StringBuffer sb = new StringBuffer();
    // 1.创建空白图片
    BufferedImage image = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);
    // 2.获取图片画笔
    Graphics graphic = image.getGraphics();
    // 3.设置画笔颜色
    graphic.setColor(Color.LIGHT_GRAY);
    // 4.绘制矩形背景
    graphic.fillRect(0, 0, WIDTH, HEIGHT);
    // 5.画随机字符
    Random ran = new Random();
    for (int i = 0; i < SIZE; i++) {
      // 取随机字符索引
      int n = ran.nextInt(CHARS.length);
      // 设置随机颜色
      graphic.setColor(getRandomColor());
      // 设置字体大小
      graphic.setFont(new Font(null, Font.BOLD + Font.ITALIC, FONT_SIZE));
      // 画字符
      graphic.drawString(CHARS[n] + "", i * WIDTH / SIZE, HEIGHT * 2 / 3);
      // 记录字符
      sb.append(CHARS[n]);
    }
    // 6.画干扰线
    for (int i = 0; i < LINES; i++) {
      // 设置随机颜色
      graphic.setColor(getRandomColor());
      // 随机画线
      graphic.drawLine(ran.nextInt(WIDTH), ran.nextInt(HEIGHT), ran.nextInt(WIDTH), ran.nextInt(HEIGHT));
    }
    // 7.返回验证码和图片
    Map<String, Object> map = new HashMap<>();
    //验证码
    map.put("code", sb.toString());
    //图片
    map.put("image", image);
    return map;
  }

  /**
   * 随机取色
   */
  public static Color getRandomColor() {
    Random ran = new Random();
    return new Color(ran.nextInt(256), ran.nextInt(256), ran.nextInt(256));
  }
}

获取验证码

@GetMapping("/verify-code")
public void getCode(HttpServletResponse response) throws Exception{
  Map<String, Object> map = VerifyUtil.createImage();
  //将图片输出给浏览器
  BufferedImage image = (BufferedImage) map.get("image");
  response.setContentType("image/png");
  OutputStream os = response.getOutputStream();
  ImageIO.write(image, "png", os);
}

页面

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>获取验证码</title>
</head>
<body onload="getVerify()">
<h1>点击图片切换验证码</h1><img id="img-verify" src="" alt="更换验证码" height="36" onclick="getVerify()">
</body>
<script>
  //获取验证码
  function getVerify(){
    document.getElementById("img-verify").src="/verify-code?"+Math.random();
  }
</script>
</html>

更多关于验证码的文章请点击查看：《java验证码》

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java如何生成登录随机验证码

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