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

 @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) { } }