使用Session进行页面跳转的实战教程-优快云博客

本文链接：https://blog.youkuaiyun.com/Guard_Jun/article/details/108986670

本文详细介绍了如何利用Session实现页面跳转。首先建立数据库并填充数据，然后创建User Bean，接着编写查询语句检查数据。通过LoginServlet响应并处理登录请求，最后在main.jsp中检查用户是否已登录，展示相应的页面。

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1.首先，我们先创建一个数据库，并且添加好数据

2.创建一个Bean包写Uesr

package org.jun.bean;
 
public class User {
	private Integer Id;
	private String UserName;
	private String Pwd;
	private String Sex;
	private Integer Age;
	
	@Override
	public String toString() {
		return "User [Age=" + Age + ", Id=" + Id + ", Pwd=" + Pwd + ", Sex="
				+ Sex + ", UserName=" + UserName + "]";
	}
	public User() {
		super();
	
	}
	
 
	public User(Integer id, String userName, String pwd, String sex, Integer age) {
		super();
		Id = id;
		UserName = userName;
		Pwd = pwd;
		Sex = sex;
		Age = age;
	}
	public int getId() {
		return Id;
	}
	public void setId(int id) {
		Id = id;
	}
	public String getUserName() {
		return UserName;
	}
	public void setUserName(String userName) {
		UserName = userName;
	}
	public String getPwd() {
		return Pwd;
	}
	public void setPwd(String pwd) {
		Pwd = pwd;
	}
	public String getSex() {
		return Sex;
	}
	public void setSex(String sex) {
		Sex = sex;
	}
	public int getAge() {
		return Age;
	}
	public void setAge(int age) {
		Age = age;
	}
}

3.写一个查询语句用来判断是否有数据和接收数据

package org.jun.test;
 
import org.jun.bean.User;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
 
import org.jun.util.DBUtil;
 
public class SelectTest {
 
	public static ArrayList<User> getUsers(String  name) {
		Connection conn= DBUtil.getConn();
		String sql="select* from book where name=?";
		PreparedStatement ps=null;
		ResultSet rs= null;
		ArrayList<User> users = new ArrayList<User>();
		try {
			ps= conn.prepareStatement(sql);
			ps.setObject(1, name);
			rs= ps.executeQuery();
			if (rs.next()) {
				User user=new User();//创建一个没有属性值的对象
				user.setId(rs.getInt("id"));//给属性赋值
				user.setUserName(rs.getString("user_name"));
				user.setPwd(rs.getString("pwd"));
				user.setSex(rs.getString("sex"));
				user.setAge(rs.getInt("age"));
				
			} 
		} catch (Exception e) {
			
		}finally{
			DBUtil.close(conn, ps, rs);
		}
		return users;
	}
 
}

4.写一个servlet下的LoginServlet.java来响应与跳转页面

package org.jun.test;
 
import java.io.IOException;
import java.io.PrintWriter;
 
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
 
import org.jun.test.Book;
import org.jun.test.BookTest;
 
public class LoginServlet extends HttpServlet {
 
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
 
		doPost(request,response);
	}
 
	public void doPost(HttpServletRequest request, HttpServletResponse response, Object pwd)
			throws ServletException, IOException {
		
		//1：设置中文编码
		request.setCharacterEncoding("utf-8");
		//2：获取参数
		String userName= request.getParameter("userName");
		//3：登录
		User user = UserManager.login(userName,pwd);
		
		//4：响应
		if(user!=null){
			HttpSession session= request.getSession();
			session.setAttribute("user", user);
			
			response.sendRedirect("main.jsp");
		}else{
			response.sendRedirect("main.jsp");
		}
	}
 
}

5.写一个main.jsp 来判断是否登陆过

 <body>
   
	<%
	User user =(User)sessoin.getAttribute("user");
	if(user!=null){
		//登录过
	}else{
		//未登录过
		reponse.sendRedirect("login.jsp");	
	}
	
	 %>
	 	这个页面只有登录过的用户才能看到，其他人无权查看！
  </body>

6.登录界面

body>
    <form action="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"/><br/>
  </body>