登录案例_需求分析以及代码实现
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，day10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：登陆失败，用户名或密码错误
分析：
1.创建项目，导入html页面，配置文件，jar包
druid.properties配置文件：
driverClassName=com.mysql.jdbc.Driver url=jdbc:mysql:///day14 username=root password=root initialSize=5 maxActive=10 maxWait=3000
login.html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<form action="" method="post">
用户名:<input type="text" name="username"><br>
密码：<input type="password" name="password"><br>
<input type="submit" value="登录">
</form>
</body>
</html>
2.创建数据库环境
CREATE TABLE USER( id INT PRIMARY KEY AUTO_INCREMENT, username VARCHAR(32) UNIQUE NOT NULL, password VARCHAR(32) NOT NULL ); SELECT * FROM USER;
3.创建com.itcast.user包，创建类User
/**
* 用户的实体类
*/
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 + '\'' +
'}';
}
}
4.编程JDBCUtils工具类
public class JDBCUtils {
// 成员变量
private static DataSource ds;
//静态模块
static {
try {
//1.加载配置文件
Properties pro = new Properties();
//使用加载配置文件，获取字节输入流
InputStream is = JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties");
pro.load(is);
//2.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();
}
}
5.创建包dao，创建UserDao，提供login方法
public class UserDao {
//声明JDBCTemplate对象共用
private JdbcTemplate template = new JdbcTemplate(JDBCUtils.getDataSource());
/**
* 登录方法
*
* @param loginUser 只有用户名和密码
* @return user包含用户全部数据,没有查询到，返回null
*/
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.class),
loginUser.getUsername(), loginUser.getPassword());
return user;
} catch (DataAccessException e) {
e.printStackTrace();
return null;
}
}
}
6、编写LoginServlet类
@WebServlet("/loginServlet")
public class LoginServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//1.设置编码
req.setCharacterEncoding("utf-8");
//2.获取请求参数
String username = req.getParameter("username");
String password = req.getParameter("password");
//3.封装user对象
User loginUser = new User();
loginUser.setUsername(username);
loginUser.setPassword(password);
//4.调用UserDao的login方法
UserDao dao = new UserDao();
User user = dao.login(loginUser);
//5.判断user
if (user == null){
//登陆失败
req.getRequestDispatcher("/failServlet").forward(req, resp);
}else {
//登陆成功
//存储数据
req.setAttribute("user", user);
//转发
req.getRequestDispatcher("/successServlet").forward(req, resp);
}
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
this.doGet(req, resp);
}
}
7、login.html中form表单的action路径的写法
虚拟目录+Servlet的资源路径
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<form action="loginServlet" method="post">
用户名:<input type="text" name="username"> <br>
密码:<input type="password" name="password"><br>
<input type="submit" value="登录">
</form>
</body>
</html>
8、编写SuccessServlet登陆成功页面和FailServlet登陆失败页面
SuccessServlet登陆成功页面：
@WebServlet(name = "successServlet", value = "/successServlet")
public class successServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request, response);
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//获取response域中共享的user对象
User user = (User) request.getAttribute("user");
if (user!= null){
//给页面写一句话
//设置编码
response.setContentType("text/html;charset=utf-8");
//输出
response.getWriter().write("登录成功！"+user.getUsername()+"欢迎您");
}
}
}
FailServlet登陆失败页面：
@WebServlet(name = "failServlet", value = "/failServlet")
public class failServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request, response);
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//给页面写一句话
//设置页面编码
response.setContentType("text/html;charset=utf-8");
//输出
response.getWriter().write("登陆失败，用户名或密码错误");
}
}
标签：username,登录,代码,req,案例,user,password,public,User From： https://www.cnblogs.com/qihaokuan/p/16950968.html