session会话跟踪

客官°小女子只卖身不卖艺 2022-04-23 15:26 258阅读 0赞

首先，index页面有 登录/访问test 两个链接，但是在没有登陆的状态下是不能够进入test里的，这个时候会强制用户登录。

index.html:  
< a href = “login”>登录< /a>< br/>  
< a href = “Test”>访问test< /a>< br/>

servlet:  
1、登录servlet(loginservlet)  
主要代码：  
String name = req.getParameter(“name”);  
String psw = req.getParameter(“password”);  
//判断该用户是否在数据库内  
//这里假设name=“admin” password = “12345”  
if(“admin”.equals(name)&&“12345”.equals(password))\{//设置session  
HttpSession session = req.getSession();  
session.setAttribute(“User”,name);  
resp.setContentType(“text/html;charset=UTF-8”);  
resp.getWriter().write(“欢迎您，”+name+"< a href=‘index.html’>返回< /a>");

\}else\{//重新登录  
resp.sendRedirct(“login.html”);  
\}

package com.sy;
    
    import java.io.IOException;
    
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import javax.servlet.http.HttpSession;
    
    public class loginservlet extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) 
    		throws ServletException, IOException {
    	req.setCharacterEncoding("UTF-8");
    	String name = req.getParameter("name");
    	String password = req.getParameter("password");
    	if("admin".equals(name) && "12345".equals(password)){
    		HttpSession session = req.getSession();
    		session.setAttribute("User", name);
    		//session.setAttribute("password", password);
    		//1、获取输出流
    		resp.setContentType("text/html;charset=UTF-8");
    		resp.getWriter().write("欢迎您，"+name+"！<a href='index.html'>返回首页</a>");
    	}else{
    		resp.sendRedirect("login.html");
    	}
    }
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) 
    		throws ServletException, IOException {
    	doPost(req,resp);
    }
    }

2、testServlet  
主要代码：  
首先获取req的session  
HttpSession session = req.getSession(false);  
if(session == null || session.getAttribute(“User”) == null)\{//用户没有登录（session里没有该User）  
resp.sendRedirect(“login”);//强制回到登录界面  
\}else\{  
String name = (String)session.getAttribute(“User”);  
resp.setContentType(“text/html;charset=UTF-8”);  
resp.getWriter().write(“welcome “+name+”!返回”)  
\}

package com.sy;
    
    import java.io.IOException;
    
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import javax.servlet.http.HttpSession;
    
    public class testservlet extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) 
    		throws ServletException, IOException {
    	HttpSession session = req.getSession(false);
    	if(session == null || session.getAttribute("User") == null){
    		System.out.println("只有登录过后才可以访问噢！");
    		resp.sendRedirect("login");
    	}else{
    		String name = (String)session.getAttribute("User");
    		resp.setContentType("text/html;charset=UTF-8");
    		resp.getWriter().write("welcome,"+name+"!<a href='index.html'>返回</a>");
    	}
    }
    @Override
    	protected void doGet(HttpServletRequest req, HttpServletResponse resp) 
    			throws ServletException, IOException {
    		doPost(req,resp);
    	}
    }

web.xml:

<servlet>
      <servlet-name>loginservlet</servlet-name>
      <servlet-class>com.sy.loginservlet</servlet-class>
      </servlet>
      <servlet-mapping>
      <servlet-name>loginservlet</servlet-name>
      <url-pattern>/login</url-pattern>
      </servlet-mapping>
      
      <servlet>
      <servlet-name>testservlet</servlet-name>
      <servlet-class>com.sy.testservlet</servlet-class>
      </servlet>
      <servlet-mapping>
      <servlet-name>testservlet</servlet-name>
      <url-pattern>/Test</url-pattern>
      </servlet-mapping>