开始敲代码前，先简单介绍下大致的想法实现：
生成验证码：
提供一个接口， 这个接口里，我们将生成的验证码存入session，然后将验证码以图片格式或者base64编码串返回给调用端。
校验验证码：
提供一个接口，这个接口里，我们收到调用端传过来的校验码，然后从session取出验证码，两个验证码都全部转小写，进行无大小写区分匹配校验，返回true/flase 。
存储验证码：
生成的验证码，在未生成图片的时候，就将4位验证码字符先存入session，以‘JCCODE’作为存取session的key。
OK，不废话，开始敲代码：
首先创建工具类，ValidateCodeUtil.java：
可以看注释，里面包含了设置验证码图片的宽高，干扰线数量，验证码个数；返回图片，返回base6编码串，存入session域等等。
import javax.imageio.ImageIO;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.util.Base64;
import java.util.Random;
/**
* @Author : JCccc
* @CreateTime : 2019/9/25
* @Description :
**/
public class ValidateCodeUtil {
private static Random random = new Random();
private int width = 165; //验证码的宽
private int height = 45; //验证码的高
private int lineSize = 30; //验证码中夹杂的干扰线数量
private int randomStrNum = 4; //验证码字符个数
private String randomString = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWSYZ";
private final String sessionKey = "JCCODE";
//字体的设置
private Font getFont() {
return new Font("Times New Roman", Font.ROMAN_BASELINE, 40);
}
//颜色的设置
private static Color getRandomColor(int fc, int bc) {
fc = Math.min(fc, 255);
bc = Math.min(bc, 255);
int r = fc + random.nextInt(bc - fc - 16);
int g = fc + random.nextInt(bc - fc - 14);
int b = fc + random.nextInt(bc - fc - 12);
return new Color(r, g, b);
}
//干扰线的绘制
private void drawLine(Graphics g) {
int x = random.nextInt(width);
int y = random.nextInt(height);
int xl = random.nextInt(20);
int yl = random.nextInt(10);
g.drawLine(x, y, x + xl, y + yl);
}
//随机字符的获取
private String getRandomString(int num){
num = num > 0 ? num : randomString.length();
return String.valueOf(randomString.charAt(random.nextInt(num)));
}
//字符串的绘制
private String drawString(Graphics g, String randomStr, int i) {
g.setFont(getFont());
g.setColor(getRandomColor(108, 190));
//System.out.println(random.nextInt(randomString.length()));
String rand = getRandomString(random.nextInt(randomString.length()));
randomStr += rand;
g.translate(random.nextInt(3), random.nextInt(6));
g.drawString(rand, 40 * i + 10, 25);
return randomStr;
}
//生成随机图片
public void getRandomCodeImage(HttpServletRequest request, HttpServletResponse response){
HttpSession session = request.getSession();
// BufferedImage类是具有缓冲区的Image类,Image类是用于描述图像信息的类
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_BGR);
Graphics g = image.getGraphics();
g.fillRect(0, 0, width, height);
g.setColor(getRandomColor(105, 189));
g.setFont(getFont());
// 干扰线
for (int i = 0; i < lineSize; i++) {
drawLine(g);
}
// 随机字符
String randomStr = "";
for (int i = 0; i < randomStrNum; i++) {
randomStr = drawString(g, randomStr, i);
}
System.out.println("随机字符："+randomStr);
g.dispose();
//移除之前的session中的验证码信息
session.removeAttribute(sessionKey);
//重新将验证码放入session
session.setAttribute(sessionKey, randomStr);
try {
// 将图片以png格式返回,返回的是图片
ImageIO.write(image, "PNG", response.getOutputStream());
} catch (Exception e) {
e.printStackTrace();
}
}
//生成随机图片的base64编码字符串
public String getRandomCodeBase64(HttpServletRequest request, HttpServletResponse response) {
HttpSession session = request.getSession();
// BufferedImage类是具有缓冲区的Image类,Image类是用于描述图像信息的类
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_BGR);
Graphics g = image.getGraphics();
g.fillRect(0, 0, width, height);
g.setColor(getRandomColor(105, 189));
g.setFont(getFont());
//干扰线
for (int i = 0; i < lineSize; i++) {
drawLine(g);
}
//随机字符
String randomStr = "";
for (int i = 0; i < randomStrNum; i++) {
randomStr = drawString(g, randomStr, i);
}
System.out.println("随机字符："+randomStr);
g.dispose();
session.removeAttribute(sessionKey);
session.setAttribute(sessionKey, randomStr);
String base64String = "";
try {
// 直接返回图片
// ImageIO.write(image, "PNG", response.getOutputStream());
//返回 base64
ByteArrayOutputStream bos = new ByteArrayOutputStream();
ImageIO.write(image, "PNG", bos);
byte[] bytes = bos.toByteArray();
Base64.Encoder encoder = Base64.getEncoder();
base64String = encoder.encodeToString(bytes);
} catch (Exception e) {
e.printStackTrace();
}
return base64String;
}
}
接下来写接口，创建一个ValidateCodeController.java，
先是生成验证码，返回图片的接口：
import com.example.demo.util.ValidateCodeUtil;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
/**
* @Author : JCccc
* @CreateTime : 2019/9/25
* @Description :
**/
@RestController
public class ValidateCodeController {
//返回验证码图片
@GetMapping("/getCaptchaImg")
public void getCaptchaImg(HttpServletRequest request, HttpServletResponse response, HttpSession session) {
try {
response.setContentType("image/png");
response.setHeader("Cache-Control", "no-cache");
response.setHeader("Expire", "0");
response.setHeader("Pragma", "no-cache");
ValidateCodeUtil validateCode = new ValidateCodeUtil();
// getRandomCodeImage方法会直接将生成的验证码图片写入response
validateCode.getRandomCodeImage(request, response);
// System.out.println("session里面存储的验证码为："+session.getAttribute("JCCODE"));
} catch (Exception e) {
e.printStackTrace();
}
}
}
用postman来调用下接口，
可以看到控制台的打印，这个验证码字符串已经存入了session（在后面的验证接口有介绍取值）
OK，接下来是编写一个校验验证码接口：
//验证码校验
@GetMapping("/checkCaptcha")
public boolean getCheckCaptcha(@RequestParam("code") String code, HttpSession session) {
try {
//toLowerCase() 不区分大小写进行验证码校验
String sessionCode= String.valueOf(session.getAttribute("JCCODE")).toLowerCase();
System.out.println("session里的验证码："+sessionCode);
String receivedCode=code.toLowerCase();
System.out.println("用户的验证码："+receivedCode);
return !sessionCode.equals("") && !receivedCode.equals("") && sessionCode.equals(receivedCode);
} catch (Exception e) {
return false;
}
}
用postman调下接口，先生成验证码模拟返回给页面了，
然后调用校验验证码接口，模拟用户在页面输入验证码，
可以看到校验正确。
最后，再补一个返回base64编码串的接口，
// 生成验证码,返回的是 base64
@GetMapping("/getCaptchaBase64")
public Object getCaptchaBase64(HttpServletRequest request, HttpServletResponse response) {
Map result = new HashMap();
try {
response.setContentType("image/png");
response.setHeader("Cache-Control", "no-cache");
response.setHeader("Expire", "0");
response.setHeader("Pragma", "no-cache");
ValidateCodeUtil validateCode = new ValidateCodeUtil();
// 返回base64
String base64String = validateCode.getRandomCodeBase64(request, response);
result.put("url", "data:image/png;base64," + base64String);
result.put("message", "created successfull");
//http://tool.chinaz.com/tools/imgtobase/ base64直接转为图片网站
System.out.println("结果：" + result.get("url"));
} catch (Exception e) {
System.out.println(e);
}
return result;
}
用postman调用一下，
控制台打印：
将url取出来，
data:image/png;base64,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
去base64编码串转图片的网站去看看，对应的验证码图：
OK，生成验证码和校验的相关教程到此结束。
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原文链接：https://blog.csdn.net/qq_35387940/article/details/101368003