记住用户信息和信息错误提示

记住用户信息和信息错误提示

用户登录成功后，跳转到列表页面，并在页面上展示当前登录的用户名称用户登录失败后，跳转回登录页面，并在页面上展示对应的错误信息

逻辑如下。

(1) 前端通过表单发送请求和数据给Web层的LoginServlet
(2)在LoginServlet中接收请求和数据[用户名和密码]
(3) LoginServlet接收到请求和数据后，调用Service层完成根据用户名和密码查询用户对象
(4) 在Service层需要编写UserService类，在类中实现login方法，方法中调用Dao层的UserMapper
(5) 在UserMapper接口中，声明一个根据用户名和密码查询用户信息的方法
(6) Dao层把数据查询出来以后，将返回数据封装到User对象，将对象交给Service层(7)Service层将数据返回给Web层
(8)Web层获取到User对象后，判断User对象，如果为Null,则将错误信息响应给登录页面，如果不为Null，则跳转到列表页面，并把当前登录用户的信息存入Session携带到列表页面。

所以首先是dao层，也就是mapper层。我们需要用到这些方法

@Select("select * from tb_user where username = #{username} and password = #{password}")
User select(@Param("username") String username,@Param("password")  String password);

@Select("select * from tb_user where username = #{username}")
User selectByUsername(String username);

 
@Insert("insert into tb_user values(null,#{username},#{password})")
void add(User user)

当然我们还需要这个实体包装类

package com.jgdabc.pojo;

/**
 * 品牌实体类
 */

public class Brand {
    // id 主键
    private Integer id;
    // 品牌名称
    private String brandName;
    // 企业名称
    private String companyName;
    // 排序字段
    private Integer ordered;
    // 描述信息
    private String description;
    // 状态：0：禁用  1：启用
    private Integer status;


    public Brand() {
    }

    public Brand(Integer id, String brandName, String companyName, String description) {
        this.id = id;
        this.brandName = brandName;
        this.companyName = companyName;
        this.description = description;
    }

    public Brand(Integer id, String brandName, String companyName, Integer ordered, String description, Integer status) {
        this.id = id;
        this.brandName = brandName;
        this.companyName = companyName;
        this.ordered = ordered;
        this.description = description;
        this.status = status;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getBrandName() {
        return brandName;
    }

    public void setBrandName(String brandName) {
        this.brandName = brandName;
    }

    public String getCompanyName() {
        return companyName;
    }

    public void setCompanyName(String companyName) {
        this.companyName = companyName;
    }

    public Integer getOrdered() {
        return ordered;
    }

    public void setOrdered(Integer ordered) {
        this.ordered = ordered;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    public Integer getStatus() {
        return status;
    }

    public void setStatus(Integer status) {
        this.status = status;
    }

    @Override
    public String toString() {
        return "Brand{" +
                "id=" + id +
                ", brandName='" + brandName + '\'' +
                ", companyName='" + companyName + '\'' +
                ", ordered=" + ordered +
                ", description='" + description + '\'' +
                ", status=" + status +
                '}';
    }
}

mapper映射的xml文件

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.jgdabc.mapper.UserMapper">

</mapper>

我们的工具类,我们会一直用到这个

package com.jgdabc.util;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.IOException;
import java.io.InputStream;

public class SqlSessionFactoryUtils {

    private static SqlSessionFactory sqlSessionFactory;

    static {
        //静态代码块会随着类的加载而自动执行，且只执行一次

        try {
            String resource = "mybatis-config.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }


    public static SqlSessionFactory getSqlSessionFactory(){
        return sqlSessionFactory;
    }
}

mybatis核心配置

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <settings>
        <!--  开启自动驼峰命名规则映射  -->
        <setting name="mapUnderscoreToCamelCase" value="true"/>
    </settings>

    <!--起别名-->
    <typeAliases>
        <package name="com.jgdabc.pojo"/>
    </typeAliases>

    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql:///mysql?serverTimezone=GMT"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <!--扫描mapper-->
        <package name="com.jgdabc.mapper"/>
    </mappers>
</configuration>

service 服务

package com.jgdabc.service;

import com.jgdabc.mapper.UserMapper;
import com.jgdabc.pojo.User;
import com.jgdabc.util.SqlSessionFactoryUtils;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;

public class UserService {
    public User login(String username,String password)
    {

        SqlSessionFactory factory = SqlSessionFactoryUtils.getSqlSessionFactory();
        SqlSession sqlSession = factory.openSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        //调用方法
        User user = mapper.select(username, password);
        sqlSession.close();


        return user;

    }
//    service里面的注册功能
    public boolean register(User user)
    {
        SqlSessionFactory factory = SqlSessionFactoryUtils.getSqlSessionFactory();
        SqlSession sqlSession = factory.openSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        User u = mapper.selectByUsername(user.getUsername());
        if (u==null)
        {
            mapper.add(user);
            sqlSession.commit();

        }
        sqlSession.close();
        return u == null;


    }

}

web层登录

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <title>login</title>

    <link href="css/login.css" rel="stylesheet">

</head>

<body>

<div id="loginDiv">
    <form action="/brand-demo01/loginServlet" method="post" id="form">
        <h1 id="loginMsg">欢迎登录系统</h1>
        <div id="errorMsg" style="color: red" tex >${login_msg } ${register_msg} </div>
        <p>Username:<input id="username" name="username"value="${cookie.username.value}" type="text"></p>

        <p>Password:<input id="password" name="password" type="password"value="${cookie.password.value}"></p>
        <p>Remember:<input id="remember" name="remember"value="1" type="checkbox"></p>
        <div id="subDiv">
            <input type="submit" class="button" value="login up">
            <input type="reset" class="button" value="reset">&nbsp;&nbsp;&nbsp;
            <a href="register.jsp">没有账号？点击注册</a>
        </div>
    </form>
</div>

</body>
</html>

Servlet登录

 //1. 接收用户名和密码
        String username = request.getParameter("username");
        String password = request.getParameter("password");
        String remember = request.getParameter("remember");


        //2. 调用MyBatis完成查询
        //2.1 获取SqlSessionFactory对象
       /* String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);*/

        SqlSessionFactory sqlSessionFactory = SqlSessionFactoryUtils.getSqlSessionFactory();
        //2.2 获取SqlSession对象
        SqlSession sqlSession = sqlSessionFactory.openSession();
        //2.3 获取Mapper
        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
        //2.4 调用方法
        User user = userMapper.select(username, password);
        //2.5 释放资源
        sqlSession.close();


        //获取字符输出流，并设置content type
        response.setContentType("text/html;charset=utf-8");
//        PrintWriter writer = response.getWriter();
        //3. 判断user释放为null
        if(user != null){
            // 登陆成功
//            writer.write("登陆成功");
            if("1".equals(remember))
            {
                Cookie c_username = new Cookie("username", username);
                Cookie c_password = new Cookie("password", password);
                //设置存活时间
                c_username.setMaxAge(60*60*24*7);
                c_password.setMaxAge(60*60*24*7);
                response.addCookie(c_username);
                response.addCookie(c_password);
            }
            HttpSession session = request.getSession();
            session.setAttribute("user",user);
            String contextPath = request.getContextPath();
            response.sendRedirect("selectAllServlet");
        }else {
//            //登录失败

            request.setAttribute("login_msg","用户名或密码错误");
            request.getRequestDispatcher("/login.jsp").forward(request,response);

web层注册，在这里我们可以去做一个验证码。

这是我们的工具类

package com.jgdabc.util;

import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Arrays;
import java.util.Random;

/**
 * 生成验证码工具类
 */
public class CheckCodeUtil {

    public static final String VERIFY_CODES = "123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    private static Random random = new Random();



    /**
     * 输出随机验证码图片流,并返回验证码值（一般传入输出流，响应response页面端，Web项目用的较多）
     *
     * @param w
     * @param h
     * @param os
     * @param verifySize
     * @return
     * @throws IOException
     */
    public static String outputVerifyImage(int w, int h, OutputStream os, int verifySize) throws IOException {
        String verifyCode = generateVerifyCode(verifySize);
        outputImage(w, h, os, verifyCode);
        return verifyCode;
    }

    /**
     * 使用系统默认字符源生成验证码
     *
     * @param verifySize 验证码长度
     * @return
     */
    public static String generateVerifyCode(int verifySize) {
        return generateVerifyCode(verifySize, VERIFY_CODES);
    }

    /**
     * 使用指定源生成验证码
     *
     * @param verifySize 验证码长度
     * @param sources    验证码字符源
     * @return
     */
    public static String generateVerifyCode(int verifySize, String sources) {
        // 未设定展示源的字码，赋默认值大写字母+数字
        if (sources == null || sources.length() == 0) {
            sources = VERIFY_CODES;
        }
        int codesLen = sources.length();
        Random rand = new Random(System.currentTimeMillis());
        StringBuilder verifyCode = new StringBuilder(verifySize);
        for (int i = 0; i < verifySize; i++) {
            verifyCode.append(sources.charAt(rand.nextInt(codesLen - 1)));
        }
        return verifyCode.toString();
    }

    /**
     * 生成随机验证码文件,并返回验证码值 (生成图片形式，用的较少)
     *
     * @param w
     * @param h
     * @param outputFile
     * @param verifySize
     * @return
     * @throws IOException
     */
    public static String outputVerifyImage(int w, int h, File outputFile, int verifySize) throws IOException {
        String verifyCode = generateVerifyCode(verifySize);
        outputImage(w, h, outputFile, verifyCode);
        return verifyCode;
    }



    /**
     * 生成指定验证码图像文件
     *
     * @param w
     * @param h
     * @param outputFile
     * @param code
     * @throws IOException
     */
    public static void outputImage(int w, int h, File outputFile, String code) throws IOException {
        if (outputFile == null) {
            return;
        }
        File dir = outputFile.getParentFile();
        //文件不存在
        if (!dir.exists()) {
            //创建
            dir.mkdirs();
        }
        try {
            outputFile.createNewFile();
            FileOutputStream fos = new FileOutputStream(outputFile);
            outputImage(w, h, fos, code);
            fos.close();
        } catch (IOException e) {
            throw e;
        }
    }

    /**
     * 输出指定验证码图片流
     *
     * @param w
     * @param h
     * @param os
     * @param code
     * @throws IOException
     */
    public static void outputImage(int w, int h, OutputStream os, String code) throws IOException {
        int verifySize = code.length();
        BufferedImage image = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
        Random rand = new Random();
        Graphics2D g2 = image.createGraphics();
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

        // 创建颜色集合，使用java.awt包下的类
        Color[] colors = new Color[5];
        Color[] colorSpaces = new Color[]{Color.WHITE, Color.CYAN,
                Color.GRAY, Color.LIGHT_GRAY, Color.MAGENTA, Color.ORANGE,
                Color.PINK, Color.YELLOW};
        float[] fractions = new float[colors.length];
        for (int i = 0; i < colors.length; i++) {
            colors[i] = colorSpaces[rand.nextInt(colorSpaces.length)];
            fractions[i] = rand.nextFloat();
        }
        Arrays.sort(fractions);
        // 设置边框色
        g2.setColor(Color.GRAY);
        g2.fillRect(0, 0, w, h);

        Color c = getRandColor(200, 250);
        // 设置背景色
        g2.setColor(c);
        g2.fillRect(0, 2, w, h - 4);

        // 绘制干扰线
        Random random = new Random();
        // 设置线条的颜色
        g2.setColor(getRandColor(160, 200));
        for (int i = 0; i < 20; i++) {
            int x = random.nextInt(w - 1);
            int y = random.nextInt(h - 1);
            int xl = random.nextInt(6) + 1;
            int yl = random.nextInt(12) + 1;
            g2.drawLine(x, y, x + xl + 40, y + yl + 20);
        }

        // 添加噪点
        // 噪声率
        float yawpRate = 0.05f;
        int area = (int) (yawpRate * w * h);
        for (int i = 0; i < area; i++) {
            int x = random.nextInt(w);
            int y = random.nextInt(h);
            // 获取随机颜色
            int rgb = getRandomIntColor();
            image.setRGB(x, y, rgb);
        }
        // 添加图片扭曲
        shear(g2, w, h, c);

        g2.setColor(getRandColor(100, 160));
        int fontSize = h - 4;
        Font font = new Font("Algerian", Font.ITALIC, fontSize);
        g2.setFont(font);
        char[] chars = code.toCharArray();
        for (int i = 0; i < verifySize; i++) {
            AffineTransform affine = new AffineTransform();
            affine.setToRotation(Math.PI / 4 * rand.nextDouble() * (rand.nextBoolean() ? 1 : -1), (w / verifySize) * i + fontSize / 2, h / 2);
            g2.setTransform(affine);
            g2.drawChars(chars, i, 1, ((w - 10) / verifySize) * i + 5, h / 2 + fontSize / 2 - 10);
        }

        g2.dispose();
        ImageIO.write(image, "jpg", os);
    }

    /**
     * 随机颜色
     *
     * @param fc
     * @param bc
     * @return
     */
    private static Color getRandColor(int fc, int bc) {
        if (fc > 255) {
            fc = 255;
        }
        if (bc > 255) {
            bc = 255;
        }
        int r = fc + random.nextInt(bc - fc);
        int g = fc + random.nextInt(bc - fc);
        int b = fc + random.nextInt(bc - fc);
        return new Color(r, g, b);
    }

    private static int getRandomIntColor() {
        int[] rgb = getRandomRgb();
        int color = 0;
        for (int c : rgb) {
            color = color << 8;
            color = color | c;
        }
        return color;
    }

    private static int[] getRandomRgb() {
        int[] rgb = new int[3];
        for (int i = 0; i < 3; i++) {
            rgb[i] = random.nextInt(255);
        }
        return rgb;
    }

    private static void shear(Graphics g, int w1, int h1, Color color) {
        shearX(g, w1, h1, color);
        shearY(g, w1, h1, color);
    }

    private static void shearX(Graphics g, int w1, int h1, Color color) {

        int period = random.nextInt(2);

        boolean borderGap = true;
        int frames = 1;
        int phase = random.nextInt(2);

        for (int i = 0; i < h1; i++) {
            double d = (double) (period >> 1)
                    * Math.sin((double) i / (double) period
                    + (6.2831853071795862D * (double) phase)
                    / (double) frames);
            g.copyArea(0, i, w1, 1, (int) d, 0);
            if (borderGap) {
                g.setColor(color);
                g.drawLine((int) d, i, 0, i);
                g.drawLine((int) d + w1, i, w1, i);
            }
        }

    }

    private static void shearY(Graphics g, int w1, int h1, Color color) {

        int period = random.nextInt(40) + 10; // 50;

        boolean borderGap = true;
        int frames = 20;
        int phase = 7;
        for (int i = 0; i < w1; i++) {
            double d = (double) (period >> 1)
                    * Math.sin((double) i / (double) period
                    + (6.2831853071795862D * (double) phase)
                    / (double) frames);
            g.copyArea(i, 0, 1, h1, 0, (int) d);
            if (borderGap) {
                g.setColor(color);
                g.drawLine(i, (int) d, i, 0);
                g.drawLine(i, (int) d + h1, i, h1);
            }

        }

    }
}

然后我们用Servlet调用这个方法

package com.jgdabc.web.servlet;

import com.jgdabc.util.CheckCodeUtil;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
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 java.io.IOException;
@WebServlet("/checkCodeServlet")
public class CheckCodeServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//        super.doGet(req, resp);
//        生成验证码
        ServletOutputStream os = resp.getOutputStream();
        String chexkCode = CheckCodeUtil.outputVerifyImage(100, 50, os, 4);
//         存入Session
        HttpSession session = req.getSession();
        session.setAttribute("checkCodeGen",chexkCode);

    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        super.doPost(req, resp);
    }
}

然后我们来看注册的前端

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">

    <title>欢迎注册</title>
    <link href="css/register.css" rel="stylesheet">
</head>
<body>

<div class="form-div">
    <div class="reg-content">
        <h1 style="text-align: center">欢迎注册</h1>
        <span style="padding-left: 50px" >已有帐号？</span> <a href="login.jsp">登录</a>
    </div>
    <form id="reg-form" action="/brand-demo01/registerServlet" method="post"  >

        <table >

            <tr >
                <td width="100"style="height: 10px">用户名</td>
                <td class="inputs">

                    <input name="username" type="text" id="username" style="margin-right: 65px">
                    <br>
                    <span id="username_err" class="err_msg" >${register_msg}</span>
                    <span id="username_err_1" class = err_msg_1 style="display: none;color: red">用户名已经存在</span>
                </td>

            </tr>

            <tr>
                <td width="60"style="height:50px">密码</td>
                <td class="inputs">
                    <input name="password" type="password" id="password" style="margin-right: 65px">
                    <br>
                    <span id="password_err" class="err_msg" style="display: none">密码格式有误</span>
                </td>
            </tr>


            <tr>
                <td style="padding-bottom: 70px">验证码</td>
                <td class="inputs">
                    <input name="checkCode" type="text" id="checkCode" style="margin-right: 65px">
                    <img id="checkCodeImg" src="/brand-demo01/checkCodeServlet" style="margin-right: 10px">
                    <a href="#" id="changeImg" >看不清？</a>
                </td>
            </tr>

        </table>

        <div class="buttons">
            <input value="注 册" type="submit" id="reg_btn" style="margin-right: 65px;margin-top: 10px" >
        </div>
        <br class="clear">
    </form>

</div>
<script>
    //给用户名输入框绑定一个失去焦点的事件
    document.getElementById("username").onblur = function ()

    {
        //

        //发送ajax请求
        //
        var username = this.value;
        //创建核心对象
        var xhttp;
        if(window.XMLHttpRequest)
        {
            xhttp = new XMLHttpRequest();
        }else {
            xhttp = new ActiveXObject("Microsoft.XMLHTTP");
        }
    //    发送请求
        xhttp.open("GET"," http://localhost:8080/brand-demo01/selectUserServlet?username="+username)
        xhttp.send();

        xhttp.onreadystatechange = function ()
        {
            if(this.readyState == 4 && this.status == 200)
            {
                // alert(this.responseText);
                if(this.responseText=="false")
                {
                    // alert(this.responseText)
                    document.getElementById("username_err_1").style.display='';
                }else {
                    document.getElementById("username_err_1").style.display='none';

                }
            }
        };
    }
</script>

<script>
    document.getElementById("changeImg").onclick = function () {
        document.getElementById("checkCodeImg").src = "/brand-demo01/checkCodeServlet?"+new Date().getMilliseconds();
    }

</script>
</body>
</html>

这里涉及一个异步请求方式

servlet层

    //1. 接收用户数据
        String username = request.getParameter("username");
        String password = request.getParameter("password");
        String checkCode = request.getParameter("checkCode");
//        System.out.println(checkCode);
        HttpSession session = request.getSession();
        String checkCodeGen =  (String) session.getAttribute("checkCodeGen");
        System.out.println(checkCodeGen);
        boolean b = checkCodeGen.equalsIgnoreCase(checkCode);
        User user = new User();
        user.setUsername(username);
        user.setPassword(password);
//        request.setAttribute("register_msg","用户已经存在");
        boolean flag = service.register(user);
//
//        System.out.println(flag);



        if(!b)
        {
            System.out.println("比对失败");
            request.setAttribute("register_msg","验证码错误,请输入验证码");
            request.getRequestDispatcher("/register.jsp").forward(request,response);
            return;
        }

//        //封装用户对象
//        User user = new User();
//        user.setUsername(username);
//        user.setPassword(password);
//        boolean flag = service.register(user);
        if (!flag)
        {
//            注册功能，跳转登录界面
            request.setAttribute("register_msg","注册成功，请登录");
            request.getRequestDispatcher("/login.jsp").forward(request,response);
        }
        else {
            //注册失败，跳转到注册页面
            request.setAttribute("register_msg","用户已经存在");
            request.getRequestDispatcher("/register.jsp").forward(request,response);
        }