图形验证码，往往常用，写下来记录一下，便于以后随时使用 

一、图片验证码工具类

import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;

public class CaptchaCodeUtil {
    /**
     * 验证码图片的宽度
     */
    private  int width=160;
    /**
     * 验证码图片的宽度
     */
    private  int height=40;
    /**
     * 干扰线的数量
     */
    private  int lineCount=20;
    /**
     * 验证码
     */
    private  String  code=null;

    /**
     * 验证码图片上字符个数
     */
    private  int  codeCount=4;

    /**
     * 验证码图片Buffer
     */
    private BufferedImage buffImg = null;

    Random random = new Random();

    public CaptchaCodeUtil(){
         createImageCode();
    }

    /**
     * 指定宽高
     * @param width
     * @param height
     */
    public CaptchaCodeUtil(int width, int height){
        this.width=width;
        this.height=height;
        createImageCode();
    }

    /**
     * 指定宽高和干扰线的数量
     * @param width
     * @param height
     * @param lineCount
     */
    public CaptchaCodeUtil(int width, int height, int lineCount){
        this.width=width;
        this.height=height;
        this.lineCount=lineCount;
        createImageCode();
    }

    /**
     * 指定宽高、验证码字符个数、干扰线数量
     * @param width
     * @param height
     * @param codeCount
     * @param lineCount
     */
    public CaptchaCodeUtil(int width, int height, int codeCount, int lineCount){
        this.width=width;
        this.height=height;
        this.codeCount=codeCount;
        this.lineCount=lineCount;
        createImageCode();
    }

    /**
     * 指定宽高、验证码字符个数、干扰线数量、
     * @param width
     * @param height
     * @param codeCount
     * @param lineCount
     * @param code
     */
    public CaptchaCodeUtil(int width, int height, int codeCount, int lineCount, String code){
        this.width=width;
        this.height=height;
        this.codeCount=codeCount;
        this.lineCount=lineCount;
        createImageCode(code);
    }

    /**
     * 生成验证码
     */
    private void createImageCode(){
        // 字体的宽度
        int fontWidth = width / codeCount;
        // 字体的高度
        int fontHeight = height - 5;
        // 偏移量
        int codeY = height - 8;

        // 图像buffer
        buffImg = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        Graphics g = buffImg.getGraphics();
        // 设置背景色
        g.setColor(getRandColor(200, 250));
        g.fillRect(0, 0, width, height);

        // 设置字体
        Font font = new Font("Fixedsys", Font.BOLD, fontHeight);
        g.setFont(font);

        // 设置干扰线
        setLine(g);

        // 添加噪点
        // 噪声率
        float yawpRate = 0.01f;
        int area = (int) (yawpRate * width * height);
        for (int i = 0; i < area; i++) {
            int x = random.nextInt(width);
            int y = random.nextInt(height);
            buffImg.setRGB(x, y, random.nextInt(255));
        }
        // 得到随机字符
        String str1 = randomStr(codeCount);
        this.code = str1;
        for (int i = 0; i < codeCount; i++) {
            String strRand = str1.substring(i, i + 1);
            g.setColor(getRandColor(1, 255));
            // a为要画出来的东西，x和y表示要画的东西最左侧字符的基线位于此图形上下文坐标系的 (x, y) 位置处
            g.drawString(strRand, i*fontWidth+3, codeY);
        }

    }
    /**
     * 生成指定字符图片
     */
    private void createImageCode(String code) {
        // 字体的宽度
        int fontWidth = width / codeCount;
        // 字体的高度
        int fontHeight = height - 5;
        int codeY = height - 8;

        // 图像buffer
        buffImg = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        Graphics g = buffImg.getGraphics();
        // 设置背景色
        g.setColor(getRandColor(200, 250));
        g.fillRect(0, 0, width, height);

        // 设置字体
        Font font = new Font("Fixedsys", Font.BOLD, fontHeight);
        g.setFont(font);

        // 设置干扰线
        setLine(g);

        // 添加噪点
        // 噪声率
        float yawpRate = 0.01f;
        int area = (int) (yawpRate * width * height);
        for (int i = 0; i < area; i++) {
            int x = random.nextInt(width);
            int y = random.nextInt(height);

            buffImg.setRGB(x, y, random.nextInt(255));
        }

        this.code = code;
        for (int i = 0; i < code.length(); i++) {
            String strRand = code.substring(i, i + 1);
            g.setColor(getRandColor(1, 255));
            // a为要画出来的东西，x和y表示要画的东西最左侧字符的基线位于此图形上下文坐标系的 (x, y) 位置处
            g.drawString(strRand, i*fontWidth+3, codeY);
        }

    }

    /**
     * 设置干扰线
     * @param g
     */
    private void setLine(Graphics g){
        for (int i = 0; i < lineCount; i++) {
            int xs = random.nextInt(width);
            int ys = random.nextInt(height);
            int xe = xs + random.nextInt(width);
            int ye = ys + random.nextInt(height);
            g.setColor(getRandColor(1, 255));
            g.drawLine(xs, ys, xe, ye);
        }

    }
    /**
     * 得到随机字符
     * @param n
     * @return
     */
    public String randomStr(int n) {
        String str1 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890";
        String str2 = "";
        int len = str1.length() - 1;
        double r;
        for (int i = 0; i < n; i++) {
            r = (Math.random()) * len;
            str2 = str2 + str1.charAt((int) r);
        }
        return str2;
    }

    /**
     * 得到随机颜色
     * @param fc
     * @param bc
     * @return
     */
    private Color getRandColor(int fc, int bc) {
        // 给定范围获得随机颜色
        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);
    }

    /**
     * 产生随机字体
     */
    private Font getFont(int size) {
        Random random = new Random();
        Font font[] = new Font[5];
        font[0] = new Font("Ravie", Font.PLAIN, size);
        font[1] = new Font("Antique Olive Compact", Font.PLAIN, size);
        font[2] = new Font("Fixedsys", Font.PLAIN, size);
        font[3] = new Font("Wide Latin", Font.PLAIN, size);
        font[4] = new Font("Gill Sans Ultra Bold", Font.PLAIN, size);
        return font[random.nextInt(5)];
    }


    /**
     * 扭曲方法
     * @param g
     * @param w1
     * @param h1
     * @param color
     */
    private void shear(Graphics g, int w1, int h1, Color color) {
        shearX(g, w1, h1, color);
        shearY(g, w1, h1, color);
    }

    private void shearX(Graphics g, int w1, int h1, Color color) {

        int period = random.nextInt(2);

        boolean borderGap = true;
        int frames = 1;
        int phase = random.nextInt(2);

        for (int i = 0; i < h1; i++) {
            double d = (double) (period >> 1)
                    * Math.sin((double) i / (double) period
                    + (6.2831853071795862D * (double) phase)
                    / (double) frames);
            g.copyArea(0, i, w1, 1, (int) d, 0);
            if (borderGap) {
                g.setColor(color);
                g.drawLine((int) d, i, 0, i);
                g.drawLine((int) d + w1, i, w1, i);
            }
        }

    }

    private void shearY(Graphics g, int w1, int h1, Color color) {

        int period = random.nextInt(40) + 10;

        boolean borderGap = true;
        int frames = 20;
        int phase = 7;
        for (int i = 0; i < w1; i++) {
            double d = (double) (period >> 1)
                    * Math.sin((double) i / (double) period
                    + (6.2831853071795862D * (double) phase)
                    / (double) frames);
            g.copyArea(i, 0, 1, h1, 0, (int) d);
            if (borderGap) {
                g.setColor(color);
                g.drawLine(i, (int) d, i, 0);
                g.drawLine(i, (int) d + h1, i, h1);
            }

        }

    }

    public void write(OutputStream sos) throws IOException {
        ImageIO.write(buffImg, "png", sos);
        sos.close();
    }

    public BufferedImage getBuffImg() {
        return buffImg;
    }

    public String getCode() {
        return code.toLowerCase();
    }
}

 二、 控制层调用

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.http.MediaType;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.UUID;
import java.util.concurrent.TimeUnit;

/**
 * @desc:图形验证码
 */
@RestController
@RequestMapping(value = "/code", produces = MediaType.APPLICATION_JSON_UTF8_VALUE)
public class CaptchaCodeController {

    @Autowired
    private StringRedisTemplate redisTemplate;

	/**
	 * 下发验证码标识给客户端，客户端也可以自己生成
	 * @return
	 */
    @GetMapping(value = "/initCode")
    public String initCode(){
        try {
            //下发验证码标识
            String captchaId=UUID.randomUUID().toString().replace("-","");
            return captchaId;
        }catch (Exception e){
             throw new BusinessException("初始化验证码异常");
        }
    }

	/**
	 * 验证码以流的形式响应给客户端
	 * @param captchaId
	 * @param response
	 * @throws IOException
	 */
    @GetMapping(value = "/draw/{captchaId}")
    public  void  drawCaptcha(@PathVariable("captchaId") String captchaId, HttpServletResponse response) throws IOException {
        //生成4位随机验证码
        String code= new CaptchaCodeUtil().randomStr(4);
        //id和验证码存入redis，3分钟有效
        redisTemplate.opsForValue().set("CODE:"+captchaId,code,3l,TimeUnit.MINUTES);
        //指定验证码长宽
        CaptchaCodeUtil vCode = new CaptchaCodeUtil(116,36,4,10,code);
        vCode.write(response.getOutputStream());
    }

    @GetMapping(value = "/verify/{captchaId}")
    public  String  verifyCaptcha(@PathVariable("captchaId") String captchaId, @PathVariable("code") String code) throws IOException {
        
        String rcode = redisTemplate.opsForValue().get("CODE:"+captchaId);
        if (!code.equals(rcode)) {
        	throw new BusinessException("图片验证码错误");
		}
		return "SUCCESS";
        
    }

}