使用Java生成图形验证码(后端)

生成图形验证码工具类: VerificationCodeUtil

package com.merce.woven.utils;

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

/**
 * @author chuan
 * @date 2019-05-05
 * @desc 图形验证码生成
 */
public class VerificationCodeUtil {

  // 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'};

  // 验证码位数
  private static final int CODE_SIZE = 4;
  // 图片上干扰线数量
  private static final int LINES = 5;
  // 图片宽度
  private static final int IMAGE_WIDTH = 80;
  // 图片高度
  private static final int IMAGE_HEIGHT = 40;
  // 图片字体大小
  private static final int FONT_SIZE = 30;

  /**
   * 生成随机验证码及图片
   * Object[0]：验证码字符串；
   * Object[1]：验证码图片。
   */
  public static Object[] createImage() {
    StringBuffer sb = new StringBuffer();
    // 1.创建空白图片
    BufferedImage image = new BufferedImage(IMAGE_WIDTH, IMAGE_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, IMAGE_WIDTH, IMAGE_HEIGHT);
    // 5.画随机字符
    Random ran = new Random();
    for (int i = 0; i < CODE_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 * IMAGE_WIDTH / CODE_SIZE, IMAGE_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(IMAGE_WIDTH), ran.nextInt(IMAGE_HEIGHT),
              ran.nextInt(IMAGE_WIDTH), ran.nextInt(IMAGE_HEIGHT));
    }
    // 7.返回验证码和图片
    return new Object[]{sb.toString(), image};
  }

  /**
   * 获取随机背景颜色(RGB)
   */
  private static Color getRandomColor() {
    Random ran = new Random();
    Color color = new Color(ran.nextInt(256), ran.nextInt(256), ran.nextInt(256));
    return color;
  }

}

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通过接口返回给前端:

（1）Spring-Jersey的rest接口返回方式:

@GET
@Path("/getCode")
public void getCode() throws IOException {
        RequestAttributes requestAttributes = RequestContextHolder.getRequestAttributes();
        ServletRequestAttributes servletRequestAttributes = (ServletRequestAttributes) requestAttributes;
        HttpServletResponse response = servletRequestAttributes.getResponse();
        HttpSession session = servletRequestAttributes.getRequest().getSession();
        
        //利用图片工具生成图片,第一个参数是生成的验证码,第二个参数是生成的图片
        Object[] objs = VerificationCodeUtil.createImage();
        //将验证码存入Session
        session.setAttribute("code",objs[0]);

        //禁止图像缓存
        response.setHeader("Pragma","no-cache");
        response.setHeader("Cache-Control", "no-cache");
        response.setDateHeader("Expires", 0);
        //将图片输出给浏览器
        BufferedImage image = (BufferedImage) objs[1];
        response.setContentType("image/png");
        OutputStream os = response.getOutputStream();
        ImageIO.write(image, "png", os);
    }

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