session会话跟踪
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>
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