0308 登录

代码展示

新建一个login.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<form action="/WEB02/LoginServlet" method="post">
	用户名:<input type="text" name="username"><br>
	密码:<input type="password" name="pwd" ><br>
	<input type="submit" value="登录">
</form>
</body>
</html>

　　

新建一个LoginServlet类

public class LoginServlet extends HttpServlet {

	public void init() throws ServletException {
		//计数器
		int sum=0;
		//获取ServletContext对象
		ServletContext context=getServletContext();
		//存入
		context.setAttribute("sum", sum);
	}
	private UserService userService=new UserService();
	public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		//获取用户名和密码
		String uname=request.getParameter("username");
		String pwd=request.getParameter("pwd");
		int count=userService.login(uname, pwd);
		if(count>0){
			//登录成功取出计数器佳佳
			int sum=(int)getServletContext().getAttribute("sum");
			sum++;
			//存入计数器
			getServletContext().setAttribute("sum", sum);
			response.getWriter().write("you are "+sum+" ok!");
		}else{
			response.getWriter().write("no");
		}
	}
	public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		doGet(request, response);
	}
}

　　

在service层中创建 userService

public class UserService {

	private UserDao userDao=new UserDao();
	public int login(String uname,String pwd){
		int count=0;
		try {
			count=userDao.login(uname, pwd);
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return count;
	}
}

　　

在dao层中创建userdao

public class UserDao {

	public int login(String uname,String pwd) throws SQLException{
		//获取链接
		Connection conn=JDBCUtils.getConn();
		//获取sql语句
		String sql="select count(*) from user where uname=? and pwd=?";
		PreparedStatement pst=conn.prepareStatement(sql);
		pst.setString(1, uname);
		pst.setString(2, pwd);
		//执行
		ResultSet rs=pst.executeQuery();
		//处理结果集
		int count=0;
		while(rs.next()){
			count=rs.getInt(1);
		}
		JDBCUtils.close(conn, pst, rs);
		return count;
	}
}

　　

运用到工具类JDBCUtils

public class JDBCUtils {

	//获取链接对象
	public static Connection getConn(){
		Connection conn=null;
		try {
			//注册驱动
			Class.forName("com.mysql.jdbc.Driver");
			//获得链接对象
			String url="jdbc:mysql://localhost:3306/java1127?characterEncoding=utf-8";
			String user="root";
			String pwd="123456";
			conn=DriverManager.getConnection(url,user,pwd);
		} catch (ClassNotFoundException | SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return conn;
	}
	//增删改释放资源
	public static void close(Connection conn,PreparedStatement pst){
		if(pst!=null){
			try {
				pst.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		if(conn!=null){
			try {
				conn.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
	}
	//查询释放资源
	public static void close(Connection conn,PreparedStatement pst,ResultSet rs){
		if(rs!=null){
			try {
				rs.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		if(pst!=null){
			try {
				pst.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		if(conn!=null){
			try {
				conn.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
	}
}

　　

 

 

 

 

 

posted @ 2021-03-08 15:50  公雪  阅读(242)  评论(0)    收藏  举报