简易登录程序（含账号密码验证码验证与数据库连接）
首先是用户需求：
1.输入用户名密码验证码
2.登录成功跳转success.jsp，展示username，欢迎您
3.登录失败跳转回登录页面
*如账号或密码错误，提示账号或密码错误
*如验证码错误，提示验证码错误
程序编写流程：
1.编写login.html登录页面
username & password & 验证码输入 三个输入框
2.编写验证码的servlet，可以参考我4月20日编写的《随机验证码生成》
3.编写LoginServlet，含有获取验证码、用户封装、判断用户名密码验证码是否一致
*先不调用数据库，直接拿输出数据与字符判断，如成功，在进行连接调用数据库判断
4.若程序运行成功，使用Druid数据库连接池技术，操作mysql，
5.使用JDBCTemplate技术封装JDBC
6.编写操作数据表中User表的Uerdao类
7.改写刚刚为了方便，进行账号密码直接判断的程序，调用Uerdao类进行判断
8.输入用户名密码验证码
9.登录成功跳转success.jsp，展示username，欢迎您
10.登录失败跳转回登录页面
*如账号或密码错误，提示账号或密码错误
*如验证码错误，提示验证码错误
首先是login.jsp页面
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>login</title>
<script>
window.onload = function(){
document.getElementById("img").onclick = function(){
this.src="/day16_loginTest/checkCodeServlet?time="+new Date().getTime();
}
}
</script>
<style>
div{
color: red;
}
</style>
</head>
<body>
<form action="/day16_loginTest/loginServlet" method="post">
<table>
<tr>
<td>用户名</td>
<td><input type="text" name="username"></td>
</tr>
<tr>
<td>密码</td>
<td><input type="password" name="password"></td>
</tr>
<tr>
<td>验证码</td>
<td><input type="text" name="checkCode"></td>
</tr>
<tr>
<td colspan="2"><img id="img" src="/day16_loginTest/checkCodeServlet"></td>
</tr>
<tr>
<td colspan="2"><input type="submit" value="登录"></td>
</tr>
</table>
</form>
<div><%=request.getAttribute("cc_error") == null ? "" : request.getAttribute("cc_error")%></div>
<div><%=request.getAttribute("login_error") == null ? "" : request.getAttribute("login_error") %></div>
</body>
</html>
然后是编写的验证码的servlet，需要注意的是需要将随机生成的验证码字符存入session，与输入的进行判断
package cn.stormtides.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 java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;
@WebServlet("/checkCodeServlet")
public class CheckCodeServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
int width = 100;
int height = 50;
//1.创建一对象，在内存中图片(验证码图片对象)
BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
//2.美化图片
//2.1 填充背景色
Graphics g = image.getGraphics();//画笔对象
g.setColor(Color.PINK);//设置画笔颜色
g.fillRect(0,0,width,height);
//2.2画边框
g.setColor(Color.BLUE);
g.drawRect(0,0,width - 1,height - 1);
String str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghigklmnopqrstuvwxyz0123456789";
//生成随机角标
Random ran = new Random();
StringBuilder sb = new StringBuilder();
for (int i = 1; i <= 4; i++) {
int index = ran.nextInt(str.length());
//获取字符
char ch = str.charAt(index);//随机字符
sb.append(ch);
//2.3写验证码
g.drawString(ch+"",width/5*i,height/2);
}
String checkCode_session = sb.toString();
//将验证码存入session
request.getSession().setAttribute("checkCode_session",checkCode_session);
//2.4画干扰线
g.setColor(Color.GREEN);
//随机生成坐标点
for (int i = 0; i < 10; i++) {
int x1 = ran.nextInt(width);
int x2 = ran.nextInt(width);
int y1 = ran.nextInt(height);
int y2 = ran.nextInt(height);
g.drawLine(x1,y1,x2,y2);
}
//3.将图片输出到页面展示
ImageIO.write(image,"jpg",response.getOutputStream());
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request,response);
}
}
然后为最主要的loginServlet.java，因为没有调用数据库，就直接和字符："zhangsan","123"比较，在运行成功后对调用数据库进行判断
package cn.stormtides.servlet;
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;
@WebServlet("/loginServlet")
public class LoginServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
request.setCharacterEncoding("utf-8");
//获取参数名称获取参数值
String username = request.getParameter("username");
String password = request.getParameter("password");
String checkCode = request.getParameter("checkCode");
//获取生成的验证码
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");
//忽略大小写比较验证码
if (checkCode_session.equalsIgnoreCase(checkCode)){
//验证码正确
if ("zhangsan".equals(username)&&"123".equals(password)){
//登陆成功
//存储信息，用户信息
session.setAttribute("user",username);
//重定向到success.jsp
response.sendRedirect(request.getContextPath()+"/success.jsp");
}else{
//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 {
//验证码错误
request.setAttribute("cc_error","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);
}
}
在运行成功后，进行数据库的有关操作
首先在数据库中创建User表，
CREATE TABLE USER(
id INT PRIMARY KEY AUTO_INCREMENT,
username VARCHAR(32) UNIQUE NULL,
PASSWORD VARCHAR(32) NOT NULL
);
INSERT INTO USER(username,PASSWORD)VALUES
('superbaby','123');
首先创建用户实体类User.java
package cn.stormtides.domain;
//用户实体类
public class User {
private int id;
private String username;
private String 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 + '\'' +
'}';
}
}
再进行编写操作数据表中User表的类，依赖于Druid连接池与Template
package cn.stormtides.dao;
import cn.stormtides.domain.User;
import cn.stormtides.util.JDBCUtils;
import org.springframework.dao.DataAccessException;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;
/**
* 操作数据表中User表的类
*/
public class UserDao {
private JdbcTemplate template=new JdbcTemplate(JDBCUtils.getDataSource());
/**
* 登录方法
* @param loginUser
* @return user
*/
public User login(User loginUser){
try{
//编写sql
String sql="select * from user where username= ? and password=?";
//调用query方法
User user = template.queryForObject(sql,
new BeanPropertyRowMapper<User>(User.class),
loginUser.getUsername(), loginUser.getPassword());
return user;
}catch (DataAccessException e){
e.printStackTrace();
return null;
}
}
}
编写JDBC工具类，使用Druid连接池
package cn.stormtides.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;
public class JDBCUtils {
private static DataSource ds;
static {
try {
//加载配置文件
Properties pro=new Properties();
InputStream is = JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties");
pro.load(is);
//初始化连接池对象
ds = DruidDataSourceFactory.createDataSource(pro);
}catch (IOException e){
e.printStackTrace();
}catch (Exception e){
e.printStackTrace();
}
}
/**
* 获取连接池对象
*/
public static DataSource getDataSource(){
return ds;
}
/**
* 获取连接Connection对象
*/
public static Connection getConnection() throws SQLException {
return ds.getConnection();
}
}
配置文件
driverClassName=com.mysql.jdbc.Driver url=jdbc:mysql://localhost:3306/day14 username=root password=root initialSize=5 maxAction=10 maxWait=3000
最后改动LoginServlet.java文件调用页面输入的账号密码验证码与数据库中的中的比较，就可以了
程序的原始代码https://github.com/StormTides/reference/tree/master/day16_loginTest
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