java实现登录验证码

import java.awt.Color;import java.awt.Font;import java.awt.Graphics;import java.awt.image.BufferedImage;import java.io.IOException;import java.io.OutputStream;import java.util.Random;import javax.imageio.ImageIO;import javax.servlet.ServletException;import org.springframework.stereotype.Service;/** * 登录验证码 * */public class ValidateCode {  /**  * 得到验证码图片  * @param out  * @param number 验证数字  * @throws ServletException  * @throws IOException  */ public void getImage(OutputStream out,String number)   throws ServletException, IOException {  //0.创建空白图片  BufferedImage image=new BufferedImage(100,30,BufferedImage.TYPE_INT_RGB);  //1.获取图片画笔  Graphics g = image.getGraphics();  Random r=new Random();  //2.设置画笔颜色(Random类中的nextInt(n)返回一个大于等于0，小于n的随机数)  g.setColor(new Color(r.nextInt(255),r.nextInt(255), r.nextInt(255)));  //3.绘制矩形的背景  g.fillRect(0, 0, 100, 30);  //4.调用自定义的方法，获取长度为4的字母数字组合的字符串  g.setColor(new Color(0,0,0));  g.setFont(new Font(null,Font.BOLD,24));  //5.设置颜色字体后，绘制字符串（x/y,最左边字符所处的位置）  g.drawString(number, 20, 24);  //6.绘制8条干扰线(alpha表示透明度)  for(int i=0;i<8;i++){   g.setColor(new Color(r.nextInt(255),r.nextInt(255), r.nextInt(255),r.nextInt(255)));   g.drawLine(r.nextInt(100), r.nextInt(30), r.nextInt(100), r.nextInt(30));  }  ImageIO.write(image, "jpeg", out); }  //自定义方法，获取长度为size的字母数字组合的字符串 public String getNumber(int size){  String str="ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";  String number="";  Random r = new Random();  for(int i=0;i<size;i++){   number+=str.charAt(r.nextInt(str.length()));  }  return number; }}

@RequestMapping(value = "/check",method={RequestMethod.GET}) @ResponseBody public void check(HttpServletRequest req) {  try {   HttpServletResponse response = this.getResponse();   response.setContentType("application/octet-stream");   response.addHeader("Content-Disposition", "attachment;filename=" + "vcode.jpeg");   String number = validateCode.getNumber(4);   validateCode.getImage(response.getOutputStream(),number);  } catch (Exception e) {     } }

<img style="width:4.4rem;height:1.9rem; margin-left:0.8rem;" src="http://127.0.0.1:8080/test/check">