java结合js获取验证码

框架springmvc

1、后台java代码：

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()));
    }
}

2、前台jsp代码

        <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>

3、js代码

$(function(){
    changeCode();
    $("#codeImg").bind("click", changeCode);
});
function changeCode() {
    $("#codeImg").attr("src", "code.do?t=" + new Date().getTime());
    $("#YZM").val("");
}