springMVC框架下验证码的生成

controller包下的代码如下

@RequestMapping(value = "yzm")
	public void getAdmin(HttpServletRequest request, HttpServletResponse response) {
		//  设置响应为图片
		response.setContentType("image/jpeg");
		//定义画布的宽高
		int width = 85;
		int height = 30;
		//创建画板
		BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
		Graphics g = image.getGraphics();
		//定义验证码的范围
		char word[] = "0123456789abcdefghijklmnopqrstuvwsyz".toCharArray();
		//随机选取  创建随机对象
		Random r = new Random();
		String yzm = "";
		//画4次
		for (int i = 0; i < 4; i++) {
			//设置画笔的颜色  随机一个颜色 rnd.nextInt(256) 随机一个0-255的int   
			g.setColor(new Color(r.nextInt(256), r.nextInt(256), r.nextInt(256)));
			//设置字体
			g.setFont(new Font("宋体", Font.BOLD, 35));
			//画验证码	
			String s = word[r.nextInt(word.length)] + "";
			yzm += s;
			//调整位置
			g.drawString(s, i * 20 + 6, 25);
		}
		request.getSession().setAttribute("yzm", yzm);
		System.out.println(yzm);
		// 画干扰点
		for (int i = 0; i < 50; i++) {
			g.setColor(new Color(r.nextInt(256), r.nextInt(256), r.nextInt(256)));
			g.drawOval(r.nextInt(width), r.nextInt(height), 1, 2);
		}

		OutputStream out;
		try {
			//将画布图片响应给页面  通过流
			out = response.getOutputStream();
			ImageIO.write(image, "jpeg", out);
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
	}

前端JS需添加点击事件完成换验证码的操作

    

      <script type="text/javascript">
		function changeimg() {
			document.getElementById("yzm").setAttribute("src", "yzm?num="+Math.random());
		}
      </script>

HTML直接就是一个img标签

<img src="yzm" style="width: 85px;height: 30px;" onclick="changeimg()"  id="yzm" />