Generate image verification code

Tool class for generating image verification code

package com.zkingcai.scf.core.utils;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileOutputStream;
import java.util.Random;

import javax.imageio.ImageIO;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

/**
 * ***************************************************************************
 *Created: March 27, 2018
 * Implemented function: picture verification code
 *Author: micha
 *Version: v0.0.1
-----------------------------------------------------------------------------
 *Modification record:
 *Date version modified by modified content
 *March 27, 2018 v0.0.1 micha created
 ****************************************************************************
 */

public class ImgCaptchaUtil {

	private static Logger logger = LogManager.getLogger(ImgCaptchaUtil.class);

	// randomly generated string
	private static final String RANDOM_STRS = "23456789ABCDEFGHJKMNPRSTUXYZ";

	private static final String FONT_NAME = "Fixedsys";
	private static final int FONT_SIZE = 24;

	private Random random = new Random();

	private int width = 110;// picture width
	private int height = 35;// Picture height
	private int lineNum = 50;// number of interference lines
	private int strNum = 4;// Randomly generate the number of characters

	/**
	 * Generate random pictures
	 */
	public BufferedImage genRandomCodeImage(StringBuffer randomCode) {
		// The BufferedImage class is an Image class with a buffer
		BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_BGR);
		// Get the Graphics object, which is convenient for various drawing operations on the image
		Graphics g = image.getGraphics();
		// set background color
		g.setColor(getRandColor(200, 250));
		g.fillRect(0, 0, width, height);

		// set the color of the interference line
		g.setColor(getRandColor(110, 120));

		// draw interference lines
		for (int i = 0; i <= lineNum; i++) {
			drowLine(g);
		}
		// draw random characters
		g.setFont(new Font(FONT_NAME, Font.ROMAN_BASELINE, FONT_SIZE));
		for (int i = 1; i <= strNum; i++) {
			randomCode.append(drowString(g, i));
		}
		g.dispose();
		return image;
	}

	/**
	 * Get a random color for a given range
	 */
	private 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);
	}

	/**
	 * draw the string
	 */
	private String drowString(Graphics g, int i) {
		g.setColor(new Color(random.nextInt(101), random.nextInt(111), random.nextInt(121)));
		String rand = String.valueOf(getRandomString(random.nextInt(RANDOM_STRS.length())));
		g.translate(random.nextInt(3), random.nextInt(3));
		int fsize = (int) (height * 0.7);
		int fy = fsize;
		g.drawString(rand, 18 * i, fy);
		return rand;
	}

	/**
	 * Draw interference lines
	 */
	private void drowLine(Graphics g) {
		int x = random.nextInt(width);
		int y = random.nextInt(height);
		int x0 = random.nextInt(16);
		int y0 = random.nextInt(16);
		g.drawLine(x, y, x + x0, y + y0);
	}

	/**
	 * Get random characters
	 */
	private String getRandomString(int num) {
		return String.valueOf(RANDOM_STRS.charAt(num));
	}

	public static void main(String[] args) {
		ImgCaptchaUtil tool = new ImgCaptchaUtil();
		StringBuffer code = new StringBuffer();
		BufferedImage image = tool.genRandomCodeImage(code);
		logger.debug(">>> random code =: " + code);
		try {
			// Output the image in memory to the client through streaming
			ImageIO.write(image, "JPEG", new FileOutputStream(new File("random-code.jpg")));
		} catch (Exception e) {
			// Record the underlying exception information
			logger.error(Exceptions.getErrorMessageWithNestedException(e));
		}

	}
}

Call the tool class, generate the image verification code, put the random verification code into the session, and write the image to the page

	/**
	 * ====================================================================
	 *Function: Get the verification code image and text (the verification code text will be saved in HttpSession)
	----------------------------------------------------------------------
	 *Modification record:
	 *Date version modified by modified content
	 *March 27, 2018 v0.0.1 micha created
	====================================================================
	 */
	@RequestMapping("/getVerifyCodeImage")
	public void getVerifyCodeImage(HttpServletRequest request, HttpServletResponse response) throws IOException {
		// Set the page to not be cached
		response.setHeader("Pragma", "no-cache");
		response.setHeader("Cache-Control", "no-cache");
		response.setDateHeader("Expires", 0);
		response.setContentType("image/jpeg");

		ImgCaptchaUtil tool = new ImgCaptchaUtil();
		StringBuffer code = new StringBuffer();
		BufferedImage image = tool.genRandomCodeImage(code);

		request.getSession().setAttribute("captcha", code.toString() + "|" + System.currentTimeMillis());
		logger.debug("The verification code generated this time is [" + code.toString() + "], which has been stored in HttpSession");
		
		// write to the browser
		ImageIO.write(image, "JPEG", response.getOutputStream());
	}

Effect