java实现登录验证码

时间：2018-06-26 编辑：猪哥来源：一聚教程网

本文实例为大家分享了java实现登录验证码的具体代码，供大家参考，具体内容如下

1、ValidateCode.java

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

2、Controller

@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) {
   
  }
 }

3、html