登录案例_需求分析以及代码实现
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"); } }
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