图片验证码温习

图片验证码作用分析：（人机交互）

项目思路：

1.将login.jsp页面和CodeServlet进行连接,产生相关的图片验证码，并返回图片到login.jsp页面

2.在LoginServlet.java中进行判定（session保存的图片验证码和login.jsp输入的checkCode)判断是否相等

相关源码：

package com.servlet;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

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;

/**
 * Servlet implementation class CodeServlet
 */
@WebServlet("/CodeServlet")
public class CodeServlet extends HttpServlet {

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        //response.getWriter().append("Served at: ").append(request.getContextPath());
         int length=100;
            int height=20;

            //1.创建一对象，验证码图片对象
            BufferedImage image = new BufferedImage(length, height, BufferedImage.TYPE_INT_RGB);
            //2.美化图片，填充背景色
            Graphics gra = image.getGraphics();
            //设置背景填充颜色
            gra.setColor(Color.white);//设置填充颜色
            gra.fillRect(0,0,length,height);//设置填充范围
            //设置字体、加粗、斜体、大小
            gra.setFont(new Font("微软雅黑",Font.BOLD,20));
            //设置字体的随机颜色数组
            Color[] colors= new Color[]{Color.BLUE,Color.GREEN,Color.RED};
            //创建要出现的验证码字符串
            String str="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890";

            Random random = new Random();
            for (int i = 1; i <=4; i++) {
                //生成随机角标索引
                int index = random.nextInt(str.length());
                //获取随机字符
                char c = str.charAt(index);
                //设置随机字符的字体随机颜色
                gra.setColor(colors[random.nextInt(colors.length)]);
                //写验证码,以及验证码应该出现的位置
                gra.drawString(c+" ",i*15+5,20);
            }
            //画2条干扰线，防止被别人破解
            for (int i = 1; i <=2 ; i++) {
                //随机生成x1点和x2点的横坐标位置
                int x1 = random.nextInt(length);
                int x2 = random.nextInt(length);
                //随机生成y1点和y2点的纵坐标位置
                int y1 = random.nextInt(height);
                int y2 = random.nextInt(height);

                //画干扰线，设置随机颜色
                gra.setColor(colors[random.nextInt(colors.length)]);
                gra.drawLine(x1,y1,x2,y2);
            }
            //将图片输出到页面展示
            ImageIO.write(image,"jpg",response.getOutputStream());
            
            response.getOutputStream().flush();
            response.getOutputStream().close();

        }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }

}

 在CodeServlet.java的doGet函数中增添以下代码，将随机产生的验证码保存到session,以便在LoginServlet.java中进行判断

package com.servlet;

import java.io.IOException;
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 javax.servlet.http.HttpSession;

import com.bean.Author;
import com.dao.AuthorDao;

/**
 * Servlet implementation class LoginServlet
 */
@WebServlet("/LoginServlet")
public class LoginServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public LoginServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        //response.getWriter().append("Served at: ").append(request.getContextPath());
        
        //内置对象request response 内置对象
        request.setCharacterEncoding("UTF-8");
        //获取session
        HttpSession session=request.getSession();
        

        //获取用户输入的验证码
        String checkCode=request.getParameter("checkCode");
        //获取session中的验证码
        String sessionCode=(String)session.getAttribute("sessionCode");
        System.out.println("session"+sessionCode);
        System.out.println("checkCode中"+checkCode);
        //校验验证码是否正确
        if(checkCode.equals(sessionCode)) {
            

            //接受用户提交的表单数据
            //request对象只对当前数据请求有效，刷新之后，数据丢失
            String username=request.getParameter("username");
            String password=request.getParameter("password");
            
            //判断用户名和密码是否正确
            //查询数据库获取数据信息
            AuthorDao dao=new AuthorDao();
            Author author=dao.CheckLogin(username,password);
            if(author!=null) {
            //session.setAttribute("username",username);
            //session.setAttribute("password",password);
            session.setAttribute("author", author);
            session.setMaxInactiveInterval(5);//若里面的数值为零或者负值的时候，表示session里面的数值永远有效；
            //若里面的数值为正的时候表示session的有效时间，单位为秒
            
            response.sendRedirect("userinfo.jsp");
            }else {
                response.sendRedirect("login.jsp");
            }
            
            
        }else {
            //验证码不对
            request.setAttribute("error_code", "验证码不匹配");
            request.getRequestDispatcher("login.jsp").forward(request,response);
            
        }
        
        
        
        
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }

}

login.jsp:

运行截图：

 

遇到的问题：

1.出现的错误：session中保存的验证码和用户输入的checkcode数值不一样，不同步，session中保存的是当前更新完之后的验证码

问题的解决：session中的数值名写错，导致session中的数值更新不及时

解决问题花费的时间：2min