用户登录案例需求：
1.编写login.html登录页面
username & password 两个输入框
2.使用Druid数据库连接池技术,操作mysql，day14数据库中user表
3.使用JdbcTemplate技术封装JDBC
4.登录成功跳转到SuccessServlet展示：登录成功！用户名,欢迎您
5.登录失败跳转到FailServlet展示：登录失败，用户名或密码错误
分析
步骤
文件树展示
1.创建项目，配置文件，jar包
druid.properties配置文件
driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql:///servlettest
username=root
password=root
initialSize=5
maxActive=10
maxWait=3000
2.登陆界面login.html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<form action="/Servlet_Demo/loginServlet" method="post">
<input type="text" name="username" placeholder="用户名">
<input type="text" name="password" placeholder="密码">
<input type="submit" value="提交">
</form>
</body>
</html>
3.数据库准备
CREATE DATABASE servlettest;
USE servlettest;
CREATE TABLE USER(
id INT PRIMARY KEY AUTO_INCREMENT,
username VARCHAR(32) UNIQUE NOT NULL,
PASSWORD VARCHAR(32) NOT NULL
);
INSERT INTO USER VALUES(null,"Ray",123);
4.创建User类，这个是用户实体类
package text.userclass;
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 + '\'' +
'}';
}
}
5.工具类JDBCUtils，这个工具类是老朋友了，使用Durid数据库连接池来获得数据库连接池对象。因为后面会使用JdbcTemplate，它会帮我们归还数据库连接，所以这里就不再写归还。
package text.utils;
import com.alibaba.druid.pool.DruidDataSourceFactory;
import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.Properties;
public class JDBCUtils {
//数据库连接池对象
private static DataSource ds;
//Druid数据库连接池配置
static{
try {
Properties pro=new Properties();
pro.load(JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties"));
ds=DruidDataSourceFactory.createDataSource(pro);
} catch (Exception e) {
e.printStackTrace();
}
}
//返回数据库连接池对象
public static DataSource getDatasource(){
return ds;
}
//返回数据库连接
public static Connection getConnection() throws SQLException {
return ds.getConnection();
}
}
6.创建UserDao类，这个类提供了login方法，我们用User用户实体类就可以在这里判断用户名和密码是否正确
package text.dao;
import org.springframework.dao.DataAccessException;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;
import text.userclass.User;
import text.utils.JDBCUtils;
public class UserDao {
private JdbcTemplate template=new JdbcTemplate(JDBCUtils.getDatasource());
/**
* 用户登陆的方法
* @param loginusername 用户登陆名和密码
* @return 所有用户信息
*/
public User login(User loginusername){
try {
String sql="select * from USER where username=? and password=?";
User user = template.queryForObject(sql,
new BeanPropertyRowMapper<User>(User.class),
loginusername.getUsername(), loginusername.getPassword());
return user;
} catch (DataAccessException e) {
e.printStackTrace();
return null;
}
}
}
7.在准备工作完成后，我这里写了一个Main类来测试一下连接是否正确（也可以不写该类）
package text;
import org.junit.Test;
import text.dao.UserDao;
import text.userclass.User;
public class main {
@Test
public void userlogin(){
User user=new User();
user.setUsername("Ray");
user.setPassword("123");
User loginuser = new UserDao().login(user);
System.out.println(loginuser);
}
}
8.测试完毕，开始写Servlet类，首先我们需要一个LoginServlet类来判断用户是否通过验证，再去跳转到对应的页面
这里如果一个个去获取值的话，再一个个封装成User类的话太麻烦了。采用工具类BeanUtils的populate()方法来简化这个过程
package text.web;
import org.apache.commons.beanutils.BeanUtils;
import text.dao.UserDao;
import text.userclass.User;
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;
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 {
request.setCharacterEncoding("utf-8");
// String username = request.getParameter("username");
// String password = request.getParameter("password");
// //新建user对象
// User user=new User();
// user.setUsername(username);
// user.setPassword(password);
Map<String, String[]> parameterMap = request.getParameterMap();
User user=new User();
try {
BeanUtils.populate(user,parameterMap);
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (InvocationTargetException e) {
e.printStackTrace();
}
//使用UserDao来判断数据库中是否有匹配数据
UserDao userDao=new UserDao();
User login = userDao.login(user);
if(login!=null){
request.setAttribute("user",user);
request.getRequestDispatcher("/successServlet").forward(request,response);
}else{
request.getRequestDispatcher("/failServlet").forward(request,response);
}
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request,response);
}
}
9.实现成功和失败的两种Servlet类
SuccessServlet类
package text.web;
import text.userclass.User;
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;
@WebServlet("/successServlet")
public class SuccessServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
User user = (User)request.getAttribute("user");
if(user!=null){
response.setContentType("text/html;charset=utf-8");
response.getWriter().write("登陆成功，"+user.getUsername()+"欢迎您");
}
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request,response);
}
}
FailServlet类
package text.web;
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;
@WebServlet("/failServlet")
public class FailServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html;charset=utf-8");
response.getWriter().write("登陆失败，账号密码可能错误");
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request,response);
}
}
结果
登陆login.html
输入对的数据
输入错的数据
