java如何生成随机图片验证码

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前台html代码

  验证码：  

注释：此处的src="/qos/dog/getVerifyCodeImg" SpringBoot页面展示Thymeleaf的语法

前台js代码

function change() {  var verifyCode = document.getElementById("verifyCodeImg");  verifyCode.src = "/qos/dog/getVerifyCodeImg?time=" + Math.random(1000); } /*-*/ /qos/dog/ 这里的路径是需要换成自己的哦

验证代码，在controller里面新建一个util文件夹，然后放入VerifyCodeUtil.java

package com.paladin.qos.util; import javax.imageio.ImageIO;import java.awt.*;import java.awt.image.BufferedImage;import java.io.ByteArrayOutputStream;import java.io.IOException;import java.util.Random; public class VerifyCodeUtil {  private static final Random random = new Random(); private static final String[] fontNames = {"宋体", "华文楷体", "黑体", "Georgia", "微软雅黑", "楷体_GB2312"};  public static String drawImage(ByteArrayOutputStream output) {  String code = "";  int width = 50;  int height = 25;   //创建图片缓冲区  BufferedImage bi = new BufferedImage(width, height, BufferedImage.TYPE_3BYTE_BGR);   Graphics2D g = bi.createGraphics();   //设置背景颜色  g.setBackground(new Color(255, 255, 255));  g.clearRect(0, 0, width, height);   StringBuilder stringBuilder = new StringBuilder();  //这里只画入四个字符  for (int i = 0; i < 4; i++) {   String s = randomChar() + "";  //随机生成字符，因为只有画字符串的方法，没有画字符的方法，所以需要将字符变成字符串再画   stringBuilder.append(s);   //添加到StringBuilder里面   float x = i * 1.0F * width / 4; //定义字符的x坐标   g.setFont(randomFont());   //设置字体，随机   g.setColor(randomColor());   //设置颜色，随机   g.drawString(s, x, height - 5);  }  code = stringBuilder.toString();//获取验证码字符串   //定义干扰线  //定义干扰线的数量（3-5条）int num = random.nextInt(max)%(max-min+1) + min;  int num = random.nextInt(5) % 3 + 3;  Graphics2D graphics = (Graphics2D) bi.getGraphics();  for (int i = 0; i < num; i++) {   int x1 = random.nextInt(width);   int y1 = random.nextInt(height);   int x2 = random.nextInt(width);   int y2 = random.nextInt(height);   graphics.setColor(randomColor());   graphics.drawLine(x1, y1, x2, y2);  }  // 释放图形上下文  g.dispose();  try {   ImageIO.write(bi, "jpg", output);  } catch (IOException e) {   e.printStackTrace();  }  return code;//为了方便取值，直接返回code，    }  //随机字体 private static Font randomFont() {  int index = random.nextInt(fontNames.length);  String fontName = fontNames[index];  int style = random.nextInt(4);   //随机获取4种字体的样式  int size = random.nextInt(20) % 6 + 15; //随机获取字体的大小(10-20之间的值)  return new Font(fontName, style, size); }  //随机颜色 private static Color randomColor() {  int r = random.nextInt(225);  int g = random.nextInt(225);  int b = random.nextInt(225);  return new Color(r, g, b); }   //随机字符 private static char randomChar() {  //A-Z,a-z,0-9,可剔除一些难辨认的字母与数字  String str = "0123456789ABCdefghiDEFGHIJopPQRVWXYZabcjklSTUmnqrstKLMNOvuwxyz";   return str.charAt(random.nextInt(str.length())); } }

最后，在controller里面引用

@RequestMapping("/getVerifyCodeImg")@ResponseBodypublic void getVerifyCodeImg(HttpServletResponse response, HttpSession session) {  ByteArrayOutputStream output = new ByteArrayOutputStream();  String code = VerifyCodeUtil.drawImage(output);  //将验证码文本直接存放到session中  session.setAttribute("verifyCode", code);  try {   ServletOutputStream out = response.getOutputStream();   output.writeTo(out);  } catch (IOException e) {   e.printStackTrace();  } }

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