用戶登錄案例需求：
- 編寫login.html登錄頁面
username & password 兩個輸入框 - 使用Druid數據庫連接池技術,操作mysql，login數據庫中user表
- 使用JdbcTemplate技術封裝JDBC
- 登錄成功跳轉到SuccessServlet展示：登錄成功！用戶名,歡迎您
- 登錄失敗跳轉到FailServlet展示：登錄失敗，用戶名或密碼錯誤
步驟：
- 創建項目，導入html頁面，配置文件，jar包
- 創建數據庫環境
- 創建類User
- 編寫工具類JDBCUtils
- 創建類UserDao,提供login方法
- 編寫LoginServlet類
- 編寫FailServlet和SuccessServlet類
- login.html中form表單的action路徑的寫法
----虛擬目錄+Servlet的資源路徑 - BeanUtils工具類，簡化數據封裝
代碼：
- html頁面、druid.properties配置文件內容、所需jar包
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<form action="/login/loginServlet" method="post">
用戶名:<input type="text" name="username"> <br>
密碼:<input type="password" name="password"><br>
<input type="submit" value="登錄">
</form>
</body>
</html>
driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql:///login
username=root
password=root
initialSize=5
maxActive=10
maxWait=3000
2.數據庫語句
CREATE DATABASE login;
USE login;
CREATE TABLE USER(
id INT PRIMARY KEY AUTO_INCREMENT,
username VARCHAR(32) UNIQUE NOT NULL,
PASSWORD VARCHAR(32) NOT NULL
);
3.User類
package cn.ycl.domain;
/**
* 用戶的實體類
*/
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 + '\'' +
'}';
}
}
- 工具類JDBCUtils
package cn.ycl.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的工具類，使用Druid連接池
*/
public class JDBCUtils {
private static DataSource dataSource;
static {
try {
//1.加載配置文件
Properties pro = new Properties();
InputStream is = JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties");
pro.load(is);
//2.初始化連接池對象
dataSource = DruidDataSourceFactory.createDataSource(pro);
} catch (IOException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* 獲取連接池對象
* @return
*/
public static DataSource getDataSource(){
return dataSource;
}
/**
* 獲取連接Connection對象
* @return
* @throws SQLException
*/
public static Connection getConnection() throws SQLException {
return dataSource.getConnection();
}
}
- UserDao類
package cn.ycl.dao;
import cn.ycl.domain.User;
import cn.ycl.util.JDBCUtils;
import org.springframework.dao.DataAccessException;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;
/**
* 操作數據庫中user表的類
*/
public class UserDao {
//聲明JdbcTemplate對象共用
private JdbcTemplate template = new JdbcTemplate(JDBCUtils.getDataSource());
/**
* 登陸
* @param loginUser 用戶名和密碼
* @return User對象
*/
public User login(User loginUser){
try{
//1.編寫sql
String sql = "select * from user where username = ? and password = ? ";
//2.調用query方法
User user = template.queryForObject(sql,
new BeanPropertyRowMapper<User>(User.class),
loginUser.getUsername(),loginUser.getPassword());
return user;
}catch (DataAccessException e){
e.printStackTrace();//記錄日誌
return null;
}
}
}
- LoginServlet類
package cn.ycl.servlet;
import cn.ycl.dao.UserDao;
import cn.ycl.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 java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.util.Map;
@WebServlet("/loginServlet")
public class LoginServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//1.設置編碼
req.setCharacterEncoding("utf-8");
//2.獲取請求參數
// String username = req.getParameter("username");
// String password = req.getParameter("password");
Map<String,String[]> map = req.getParameterMap();
//3.封裝user對象
User loginuser = new User();
//使用BeanUtils封裝
try {
BeanUtils.populate(loginuser,map);
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (InvocationTargetException e) {
e.printStackTrace();
}
//4.調用UserDao的login方法
UserDao dao = new UserDao();
User user = dao.login(loginuser);
//5.判斷user
if (user == null){
//登陸失敗
req.getRequestDispatcher("/failServlet").forward(req,resp);
}else {
//登陸成功
//存儲數據
req.setAttribute("user",user);
//轉發
req.getRequestDispatcher("successServlet").forward(req,resp);
}
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
this.doGet(req,resp);
}
}
- FailServlet和SuccessServlet類
package cn.ycl.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 java.io.IOException;
@WebServlet("/failServlet")
public class FailServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//設置編碼
resp.setContentType("text/html;charset=utf-8");
//打印文字
resp.getWriter().write("登陸失敗，用戶名或密碼錯誤" );
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
this.doGet(req,resp);
}
}
package cn.ycl.servlet;
import cn.ycl.domain.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 {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
User user =(User) req.getAttribute("user");
if (user!=null){
//設置編碼
resp.setContentType("text/html;charset=utf-8");
//打印文字
resp.getWriter().write("登陸成功，"+user.getUsername()+",歡迎你！" );
}
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
this.doGet(req,resp);
}
}