session 实例,登录并在成功界面显示欢迎

最新推荐文章于 2023-10-27 01:06:00 发布

原创最新推荐文章于 2023-10-27 01:06:00 发布 · 3.3k 阅读

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#session实例 #session登录并获取

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该博客详细介绍了如何在Java Web开发中利用session进行用户登录操作。首先通过HttpServletRequest对象获取session实例，然后设置session属性存储User对象。接着在后台通过getAttribute方法获取session中的User对象，打印用户名。最后说明了前台如何通过EL表达式获取session中的用户名称。涉及的文件包括User.java、DBLink.java、UserDao.java、UserDaoImpl.java以及LoginServlet.java。

session 实例

主要用到的 session 方法有:

获得session对象
HttpSession session = request.getSession();
设置session属性
User user = new User();
user.setName(name);
session.setAttribute(“user”, user);
后台获取 session 属性
User usr = (User)session.getAttribute(“user”);
System.out.println(usr.getName());
前台获取 session 值
${ user.name }

全部文件如下 :

User.java

package domain;

public class User {
    private String name ;
    private String password ;

    public String getName() { return name; }
    public void setName(String name) { this.name = name; }
    public String getPassword() { return password; }
    public void setPassword(String password) { this.password = password; }
}

DBlink.java

package com.ck.DB;

import java.sql.Connection;
import java.sql.Driver;
import java.sql.DriverManager;

public class DBLink {
     String driver ="com.mysql.jdbc.Driver";
     String url = "jdbc:mysql://localhost:3306/blogs?useUnicode=true&characterEncoding=utf-8";
     String user = "root";
     String password = "root";

     public Connection conn ;
     public DBLink(){
         try {
	         //注册驱动
	         Class.forName(driver);
	         conn = DriverManager.getConnection(url,user,password);
	
	         if (!conn.isClosed()) {
	             System.out.println("数据库连接成功！");
	         }
	    } catch (Exception e) {
	             e.printStackTrace();
	     }
     }
    public void close(){
        try {
            this.conn.close();
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}

UserDao.java

package com.ck.Dao;

public  interface UserDao {
    public boolean Login(String name, String password);
}

UserDaoImpl.java ( 是大写的 i , impl ,不是两个 L )

package com.ck.DaoImpl;

import com.ck.DB.DBLink;
import com.ck.Dao.UserDao;

import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class UserDaoImpl implements UserDao {

    /**
     * 用户登录方法
     * @param name
     * @param password
     * @return 布尔值，为true 时登录成功， false 时登录失败
     */
    @Override
    public boolean Login(String name, String password) {
        boolean flag = false ;
        try {
            DBLink dbLink =  new DBLink();
            String sql = " select * from t_user where name = '"+name+"'and password ='"+password+"'";
            PreparedStatement ps = dbLink.conn.prepareStatement(sql);
            ResultSet rs = ps.executeQuery();
            if (rs.next()){
                flag = true ;
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return flag;
    }
}

LoginServlet.java

package com.ck.setvlet;

import com.ck.DB.DBLink;
import com.ck.Dao.UserDao;
import com.ck.DaoImpl.UserDaoImpl;
import domain.User;
import sun.security.pkcs11.Secmod;
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 javax.servlet.http.HttpSession;
import java.io.IOException;

@WebServlet("/LoginServlet")
public class LoginServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String name = request.getParameter("name");
        String password = request.getParameter("password");
        UserDao dao = new UserDaoImpl();
        boolean login = dao.Login(name, password);
        String message = "";
        if (login){
        	//获得session对象
        	HttpSession session = request.getSession();
        	//设置session属性
        	User user = new User();
        	user.setName(name);
     	
        	session.setAttribute("user", user);
        	User usr = (User)session.getAttribute("user");
        	System.out.println(usr.getName());
            message = "登录成功！！！";
            request.setAttribute("message",message);
            request.getRequestDispatcher("success.jsp").forward(request,response);
        }else{
            message = "登录失败，请重新输入。";
            request.setAttribute("message",message);
            request.getRequestDispatcher("index.jsp").forward(request,response);
        }
    }
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    	doPost(request, response);
    }
}