注册案例-验证码

1.编写html注册界面（这里没有编写codeError.jsp）

重点是验证码添加一个onclick事件，点击更改验证码

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
<script>
    function  change(obj) {
        //  传递一个时间戳 更新servlet访问的地址
        obj.src="codeServlet?"+new Date().getTime();
    }
    </script>
</head>
<body>
<h2>注册页面</h2>
<form action="registerServlet" method="post">
    账号<input type="text" name="username"><br>
    密码<input type="password" name="password"><br>
    昵称<input type="text" name="nickname"><br>
    验证码<input type="text" name="code">
    <img src="codeServlet" alt="验证码" style="cursor: pointer" onclick="change(this);"><br>
    <input type="submit" value="注册">
</form>
</body>
</html>

2.编写验证码CodeSerlet

重点是将生成的验证码保存在session中，用于注册界面中与用户输入的校验比对

package com.itheima.code;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

/**
 * Created by tps on 2018/7/7.
 */
@WebServlet("/codeServlet")
public class CodeServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        // gui 生成图片

        // 1 高和宽

        int height = 30;

        int width = 60;

        String data = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789abcdefghijklmnopqrstuvwxyz";

        Random random = new Random();

        // 2 创建一个图片

        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

        // 3 获得画板

        Graphics g = image.getGraphics();

        // 4 填充一个矩形

        // * 设置颜色

        g.setColor(Color.BLACK);

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

        g.setColor(Color.WHITE);

        g.fillRect(1, 1, width - 2, height - 2);

        // * 设置字体

        g.setFont(new Font("宋体", Font.BOLD | Font.ITALIC, 25));

        StringBuffer sb = new StringBuffer();

        // 5 写随机字

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

            // 设置颜色--随机数

            g.setColor(new Color(random.nextInt(255), random.nextInt(255), random.nextInt(255)));

            // 获得随机字

            int index = random.nextInt(data.length());

            String str = data.substring(index, index + 1);

            // 写入

            g.drawString(str, width / 6 * (i + 1), 20);
            sb.append(str);//  获取验证码数据

        }
        //  验证码保存到session中
        request.getSession().setAttribute("code",sb.toString());

        // 6 干扰线

        for (int i = 0; i < 3; i++) {

            // 设置颜色--随机数

            g.setColor(new Color(random.nextInt(255), random.nextInt(255), random.nextInt(255)));

            // 随机绘制先

            g.drawLine(random.nextInt(width), random.nextInt(height), random.nextInt(width), random.nextInt(height));

            // 随机点

            g.drawOval(random.nextInt(width), random.nextInt(height), 2, 2);

        }

        // end 将图片响应给浏览器
        ImageIO.write(image, "jpg", response.getOutputStream());
    }
}

3.编写RegisterServlet注册服务

重点是根据属性名称获取储存在session中的验证码用于比对

package com.itheima.code;
import com.itheima.Utils.DruidUtils;
import org.springframework.dao.DataAccessException;
import org.springframework.jdbc.core.JdbcTemplate;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/**
 * description:<校验用户是否可以注册>
 * create by Richard  on  2018-07-08
 */
@WebServlet(name = "registerServlet", urlPatterns = "/registerServlet")
public class RegisterServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        response.setContentType("text/html;charset=utf-8");
            String username = request.getParameter("username");
            String password = request.getParameter("password");
            String nickname = request.getParameter("nickname");
            //获取用户输入（表单提交）的验证码
            String input_code = request.getParameter("code");
             //根据属性名称获取储存在session中的验证码
            String session_code = (String) request.getSession().getAttribute("code");
            //验证码判空
            if(input_code!=null){
                //  验证码是否一致 如果一致 才进行数据库注册插入操作
                if(input_code.equalsIgnoreCase(session_code)){
                    //  验证码正确 进行数据库注册插入操作。。。
                    String sql = "insert into users values(null,?,?,?)";
                    JdbcTemplate jdbcTemplate = new JdbcTemplate(DruidUtils.getDataSource());
                    try {
                       jdbcTemplate.update(sql, username, password, nickname);
                    } catch (DataAccessException e) {
                        e.printStackTrace();
                    }
                    System.out.println(username+" 注册成功 ! ");
                }else{
                    // 验证码错误 携带错误 跳回注册页面
                    request.setAttribute("code_error","验证码错误");
                    request.getRequestDispatcher("/codeError.jsp").forward(request,response);
                }
            }else {
                //获取不到用户输入的验证码的话直接报错（偷懒了）
                throw new RuntimeException("验证码必须输入");
            }
        }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        doPost(request, response);
    }
}