java结合js获取验证码

package com.fh.controller.system.secCode;

import java.awt.Color;

import java.awt.Font;

import java.awt.Graphics2D;

import java.awt.font.FontRenderContext;

import java.awt.geom.Rectangle2D;

import java.awt.image.BufferedImage;

import java.io.ByteArrayOutputStream;

import java.io.IOException;

import java.util.Random;

import javax.imageio.ImageIO;

import javax.servlet.ServletOutputStream;

import javax.servlet.http.HttpServletResponse;

import org.apache.shiro.SecurityUtils;

import org.apache.shiro.session.Session;

import org.apache.shiro.subject.Subject;

import org.springframework.stereotype.Controller;

import org.springframework.web.bind.annotation.RequestMapping;

import com.fh.util.Const;

/**

 * 类名称：登录验证码

 * 类描述：

 * 作者单位： FHqq313596790

 * 联系方式：

 * @version

 */

@Controller

@RequestMapping("/code")

public class SecCodeController {

    @RequestMapping

    public void generate(HttpServletResponse response){

        ByteArrayOutputStream output = new ByteArrayOutputStream();

        String code = drawImg(output);

        Subject currentUser = SecurityUtils.getSubject();

        Session session = currentUser.getSession();

        session.setAttribute(Const.SESSION_SECURITY_CODE, code);

        try {

            ServletOutputStream out = response.getOutputStream();

            output.writeTo(out);

        } catch (IOException e) {

            e.printStackTrace();

        }

    }

    private String drawImg(ByteArrayOutputStream output){

        String code = "";

        for(int i=0; i<4; i++){

            code += randomChar();

        }

        int width = 70;

        int height = 25;

        BufferedImage bi = new BufferedImage(width,height,BufferedImage.TYPE_3BYTE_BGR);

        Font font = new Font("Times New Roman",Font.PLAIN,20);

        Graphics2D g = bi.createGraphics();

        g.setFont(font);

        Color color = new Color(66,2,82);

        g.setColor(color);

        g.setBackground(new Color(226,226,240));

        g.clearRect(0, 0, width, height);

        FontRenderContext context = g.getFontRenderContext();

        Rectangle2D bounds = font.getStringBounds(code, context);

        double x = (width - bounds.getWidth()) / 2;

        double y = (height - bounds.getHeight()) / 2;

        double ascent = bounds.getY();

        double baseY = y - ascent;

        g.drawString(code, (int)x, (int)baseY);

        g.dispose();

        try {

            ImageIO.write(bi, "jpg", output);

        } catch (IOException e) {

            e.printStackTrace();

        }

        return code;

    }

    private char randomChar(){

        Random r = new Random();

        String s = "ABCDEFGHJKLMNPRSTUVWXYZ0123456789";

        return s.charAt(r.nextInt(s.length()));

    }

}

        <div class="item clearfix">

            <label><span>*</span>验证码：</label>

          <div class="inputBox"><input class="yzm" name="YZM" id="YZM" type="text">

            <img src="static/gysreg/images/pic.jpg" width="127" height="41" id="codeImg" alt="点击更换" title="点击更换"></div>

        </div>

$(function(){

    changeCode();

    $("#codeImg").bind("click", changeCode);

});

function changeCode() {

    $("#codeImg").attr("src", "code.do?t=" + new Date().getTime());

    $("#YZM").val("");

}