## 案例：验证码
1. 案例需求：
1. 访问带有验证码的登录页面login.jsp
2. 用户输入用户名，密码以及验证码。
* 如果用户名和密码输入有误，跳转登录页面，提示:用户名或密码错误
* 如果验证码输入有误，跳转登录页面，提示：验证码错误
* 如果全部输入正确，则跳转到主页success.jsp，显示：用户名,欢迎您
2. 分析：
package domain;
/**
* 用户 实体类
*/
public class User {
private int id;
private String username;
private String password;
public User() {
}
public User(int id, String username, String password) {
this.id = id;
this.username = username;
this.password = password;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
@Override
public String toString() {
return "User{" +
"id=" + id +
", username=‘" + username + ‘\‘‘ +
", password=‘" + password + ‘\‘‘ +
‘}‘;
}
}
package util;
import com.alibaba.druid.pool.DruidDataSourceFactory;
import javax.sql.DataSource;
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.Properties;
/**
* JDBC工具类 druid
*/
public class JDBCUtils {
private static DataSource ds;
static {
try {
//1.加载配置文件
Properties properties = new Properties();
//使用ClassLoader加载配置文件，获取字节输入流
InputStream resourceAsStream = JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties");
properties.load(resourceAsStream);
//2.初始化连接池对象
ds = DruidDataSourceFactory.createDataSource(properties);
} catch (IOException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* 获取Connection对象
*/
public static Connection getConnection() throws SQLException {
return ds.getConnection();
}
/**
* 获取连接池对象
*/
public static DataSource getDataSource(){
return ds;
}
}
package dao;
import domain.User;
import org.springframework.dao.DataAccessException;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;
import util.JDBCUtils;
/**
* 操作数据库User表的类
* */
public class UserDao {
//声明JDBCTemplate对象共用
private JdbcTemplate jdbcTemplate = new JdbcTemplate(JDBCUtils.getDataSource());
/**
* 登录方法
* @param loginUser 只有用户和密码
* @return user返回用户的所有信息
*/
public User login(User loginUser){
try {
String sql = "select * from user where username=? and password = ?";
//将查询的结果封装为USER
User user = jdbcTemplate.queryForObject(sql,
new BeanPropertyRowMapper<User>(User.class),
loginUser.getUsername(), loginUser.getPassword());
return user;
} catch (DataAccessException e) {
e.printStackTrace();
return null;
}
}
}
package web.servlet;
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 javax.servlet.http.HttpSession;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;
/**
验证码 案例
*/
@WebServlet( "/checkCodeServlet")
public class CheckCodeServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//1.创建一个对象，在内存中 存放图片
int width = 100;
int heigth = 50;
BufferedImage image = new BufferedImage(width,heigth,BufferedImage.TYPE_INT_RGB);
//2.美化图片
//2.1填充背景色
Graphics graphics = image.getGraphics();//画笔对象
graphics.setColor(Color.PINK);//设置画笔颜色
graphics.fillRect(0,0,width,heigth);//填充矩形
//2.2画边框
graphics.setColor(Color.BLUE);
graphics.drawRect(0,0,width-1,heigth-1);//因为画笔有1px 所以要减一
//2.3填写验证码
String str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
StringBuilder img_str = new StringBuilder();//用来存储验证码信息
Random random = new Random();
for (int i = 1; i <=4 ; i++) {
int index = random.nextInt(str.length());
graphics.drawString(str.charAt(index)+"",width/5*i,heigth/2);
img_str.append(str.charAt(index));
}
HttpSession session = request.getSession();
session.setAttribute("checkCode_session",img_str.toString());
//2.4画干扰线
graphics.setColor(Color.green);
for (int i = 0; i <10 ; i++) {
int x1 = random.nextInt(width);
int x2 = random.nextInt(width);
int y1 = random.nextInt(heigth);
int y2 = random.nextInt(heigth);
graphics.drawLine(x1,y1,x2,y2);
}
//3.将图片输出至页面展示
ImageIO.write(image,"jpg",response.getOutputStream());
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request,response);
}
}
package web.servlet;
import dao.UserDao;
import domain.User;
import org.apache.commons.beanutils.BeanUtils;
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 java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.util.Map;
@WebServlet("/loginServlet")
public class LoginServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//1.设置编码
request.setCharacterEncoding("utf-8");
//2.获取请求参数
String login_username = request.getParameter("username");
String login_password = request.getParameter("password");
String login_checkCode = request.getParameter("checkCode");
//3.获取验证码
HttpSession session = request.getSession();
String checkCode_session = (String) session.getAttribute("checkCode_session");
//删除session中存储的验证码
session.removeAttribute("checkCode_session");
//4.判断验证码是否正确 忽略大小写比较
if(login_checkCode!=null && checkCode_session.equalsIgnoreCase(login_checkCode)){
//5.验证码正确 判断账号与密码是否正确
User loginUser = new User();
loginUser.setUsername(login_username);
loginUser.setPassword(login_password);
UserDao userDao = new UserDao();
User user = userDao.login(loginUser);
if(user==null){
//登录失败
//存储提示信息到request
request.setAttribute("login_error","用户名或密码错误");
//转发到登录页面
request.getRequestDispatcher("/login.jsp").forward(request,response);
}else{
//登录成功
// 存储信息，用户信息 因为User信息可能跨越很多页面，所以使用session而不使用request
session.setAttribute("user",user.getUsername());
//重定向到success.jsp
response.sendRedirect(request.getContextPath()+"/success.jsp");
}
}else{
request.setAttribute("cc_error","验证码错误");
//验证码错误
request.getRequestDispatcher("login.jsp").forward(request,response);
}
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request,response);
}
}
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>登录案例</title>
<!--
分析：
点击图片，需要换一张
1.给超链接和图片绑定单击事件
2.重新设置图片的src属性值
-->
<script>
window.onload = function () {
document.getElementById("img").onclick= function () {
this.src = "${pageContext.request.contextPath}/checkCodeServlet?"+new Date().getTime();
}
}
</script>
</head>
<body>
<form action="${pageContext.request.contextPath}/loginServlet" method="post">
<table>
<tr>
<td>用户名</td>
<td><input type="text" placeholder="请输入用户名" name="username"></tr></td>
<tr>
<td>密码</td>
<td><input type="text" placeholder="请输入用户密码" name="password"></td>
</tr>
<tr >
<td>验证码</td>
<td><input type="text" placeholder="请输入验证码" name="checkCode"></td>
</tr>
<tr>
<td colspan="2"><img id="img" src="${pageContext.request.contextPath}/checkCodeServlet"></td>
</tr>
<tr>
<td colspan="2"><input type="submit" value="登录"></td>
</tr>
</table>
</form>
${requestScope.cc_error}
${requestScope.login_error}
</body>
</html>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>登录成功页面</title>
</head>
<body>
<%
HttpSession session1 = request.getSession();
String user = (String) session1.getAttribute("user");
out.print(user+"欢迎登录");
%>
</body>
</html>
原文地址：https://www.cnblogs.com/yyanghang/p/12236131.html
时间： 2024-08-08 19:24:49