现在的web项目基本都是前后端分离的,后台只需要整理数据传给前端进行渲染就行。
验证码也是web中不可缺少的一部分,再以前的前后端不分离的场景中,一般是把图片以io流的方式传给前端,同时把内容存到session中,在前端请求验证的时候就根据request取出验证码的内容进行比对验证。但是前后端分离之后,尤其是跨域之后,每一次请求session将会对应不上,也就无法取出验证码的内容值进行验证啦。
由于前端的<img>标签的src属性支持bese64编码的图片源,所以后台可以将生成的验证码以base64编码形式传给前台进行展示,同时将验证码的内容一起传给前台,考虑到安全性的问题,可以将验证码的内容也经过base64编码,这样每次验证请求的时候就可以对用户输入的验证码进行base64编码之后比对验证。
代码实例:
1.验证码类(包括图片、图片内容)
@Data
@NoArgsConstructor
@AllArgsConstructor
public class ImgResult {
String img;
String code;
}
2.生成验证码工具类,这里生成图片的部分是在网上找的,自己生成的是真的丑,把生成的jpg用base64压缩成字符串给
package cn.wzy.util;
import sun.misc.BASE64Encoder;
import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Arrays;
import java.util.Random;
/**
* Created by Wzy
* on 2018/5/11
*/
public class VerifyCodeUtils {
//使用到Algerian字体,系统里没有的话需要安装字体,字体只显示大写,去掉了1,0,i,o几个容易混淆的字符
public static final String VERIFY_CODES = "23456789ABCDEFGHJKLMNPQRSTUVWXYZ";
private static Random random = new Random();
/**
* 使用系统默认字符源生成验证码
*
* @param verifySize 验证码长度
* @return
*/
public static String generateVerifyCode(int verifySize) {
return generateVerifyCode(verifySize, VERIFY_CODES);
}
/**
* 使用指定源生成验证码
*
* @param verifySize 验证码长度
* @param sources 验证码字符源
* @return
*/
public static String generateVerifyCode(int verifySize, String sources) {
if (sources == null || sources.length() == 0) {
sources = VERIFY_CODES;
}
int codesLen = sources.length();
Random rand = new Random(System.currentTimeMillis());
StringBuilder verifyCode = new StringBuilder(verifySize);
for (int i = 0; i < verifySize; i++) {
verifyCode.append(sources.charAt(rand.nextInt(codesLen - 1)));
}
return verifyCode.toString();
}
/**
* 输出指定验证码图片流
*
* @param w
* @param h
* @param os
* @param code
* @throws IOException
*/
public static void outputImage(int w, int h, OutputStream os, String code) throws IOException {
int verifySize = code.length();
BufferedImage image = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
Random rand = new Random();
Graphics2D g2 = image.createGraphics();
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
Color[] colors = new Color[5];
Color[] colorSpaces = new Color[]{Color.WHITE, Color.CYAN,
Color.GRAY, Color.LIGHT_GRAY, Color.MAGENTA, Color.ORANGE,
Color.PINK, Color.YELLOW};
float[] fractions = new float[colors.length];
for (int i = 0; i < colors.length; i++) {
colors[i] = colorSpaces[rand.nextInt(colorSpaces.length)];
fractions[i] = rand.nextFloat();
}
Arrays.sort(fractions);
g2.setColor(Color.GRAY);// 设置边框色
g2.fillRect(0, 0, w, h);
Color c = getRandColor(200, 250);
g2.setColor(c);// 设置背景色
g2.fillRect(0, 2, w, h - 4);
//绘制干扰线
Random random = new Random();
g2.setColor(getRandColor(160, 200));// 设置线条的颜色
for (int i = 0; i < 20; i++) {
int x = random.nextInt(w - 1);
int y = random.nextInt(h - 1);
int xl = random.nextInt(6) + 1;
int yl = random.nextInt(12) + 1;
g2.drawLine(x, y, x + xl + 40, y + yl + 20);
}
// 添加噪点
float yawpRate = 0.05f;// 噪声率
int area = (int) (yawpRate * w * h);
for (int i = 0; i < area; i++) {
int x = random.nextInt(w);
int y = random.nextInt(h);
int rgb = getRandomIntColor();
image.setRGB(x, y, rgb);
}
shear(g2, w, h, c);// 使图片扭曲
g2.setColor(getRandColor(100, 160));
int fontSize = h - 4;
Font font = new Font("Algerian", Font.ITALIC, fontSize);
g2.setFont(font);
char[] chars = code.toCharArray();
for (int i = 0; i < verifySize; i++) {
AffineTransform affine = new AffineTransform();
affine.setToRotation(Math.PI / 4 * rand.nextDouble() * (rand.nextBoolean() ? 1 : -1), (w / verifySize) * i + fontSize / 2, h / 2);
g2.setTransform(affine);
g2.drawChars(chars, i, 1, ((w - 10) / verifySize) * i + 5, h / 2 + fontSize / 2 - 10);
}
g2.dispose();
ImageIO.write(image, "jpg", os);
}
private static 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);
}
private static int getRandomIntColor() {
int[] rgb = getRandomRgb();
int color = 0;
for (int c : rgb) {
color = color << 8;
color = color | c;
}
return color;
}
private static int[] getRandomRgb() {
int[] rgb = new int[3];
for (int i = 0; i < 3; i++) {
rgb[i] = random.nextInt(255);
}
return rgb;
}
private static void shear(Graphics g, int w1, int h1, Color color) {
shearX(g, w1, h1, color);
shearY(g, w1, h1, color);
}
private static 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 static void shearY(Graphics g, int w1, int h1, Color color) {
int period = random.nextInt(40) + 10; // 50;
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);
}
}
}
/**
* 获取随机验证码及其加密图片
*
* @param w
* @param h
* @param size
* @return
* @throws IOException
*/
public static ImgResult VerifyCode(int w, int h, int size) throws IOException {
BASE64Encoder encoder = new BASE64Encoder();
ImgResult rs = new ImgResult();
String code = generateVerifyCode(size).toLowerCase();
rs.setCode(encoder.encode(code.getBytes()));
ByteArrayOutputStream data = new ByteArrayOutputStream();
outputImage(w, h, data, code);
rs.setImg(encoder.encode(data.toByteArray()));
return rs;
}
}
3.测试类调用VerifyCode静态方法
public class Main {
public static void main(String[] args) throws IOException {
ImgResult rs = VerifyCodeUtils.VerifyCode(40,20,4);
System.out.println(rs.getImg());
System.out.println(rs.getCode());
}
}
结果:最后一行为验证码的内容。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aGNhag==
此时前端就可以把base64编码后的图片展示出来:中间的内容省略掉
<img src="data:image/gif;base64,/9j/4AAQSkZ.....//2Q==">
验证码的样子: