JavaWeb学习-MVC基础开发系列-4-用户注销功能

前面一篇实现了用户登录过程，这篇来学习下如何把用户注销。用户注销，实际上就是把session对象给销毁。但是我们前面一篇没有使用session对象，所以这里我们先把前面文章使用request域对象保存user对象改成存储在session中，然后来看用户注销功能的实现过程。

 

1.优化前一篇代码

前面一篇，我们把用户登录成功的用户对象存在request域中，这个有两点不好。第一，存session更好，多个页面能拿到这个用户对象。第二个没有判断登录失败的情况。现在把LoginServlet.java代码修改如下

package com.anthony.web.servlet;

import java.io.IOException;
import java.lang.reflect.InvocationTargetException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.beanutils.BeanUtils;

import com.anthony.domain.User;
import com.anthony.service.UserService;
import com.anthony.service.impl.UserServiceImpl;


public class LoginServlet extends HttpServlet {

	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		req.setCharacterEncoding("UTF-8");
		resp.setContentType("text/html;charset=UTF-8");
		//获取表单数据
		User user = new User();
		try {
			BeanUtils.populate(user, req.getParameterMap());
			// 调用业务方法
			UserService us = new UserServiceImpl();
			User u = us.login(user);
			//判断u是否为空
			if(u !=null) {
				//登录成功
				//分发转向
				req.getSession().setAttribute("u", u);
				req.getRequestDispatcher("/index.jsp").forward(req, resp);
			}else {
				//登录失败就让用户跳转登录页面
				resp.sendRedirect(req.getContextPath() +"/login.jsp");
			}
		} catch (IllegalAccessException e) {
			e.printStackTrace();
		} catch (InvocationTargetException e) {
			e.printStackTrace();
		}
		
		
	}

	protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		doGet(req,resp);
	}
	
	

}

添加判断，登录成功就把u对象存到session对象中，如果u等于空，也就是登录失败，就跳转到登录页面。

 

2.注销功能实现

2.1index.jsp链接添加跳转到LogoutServlet.java

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>







	
	
		登录
		注册
	
	
	
		欢迎您：${u.username}注销
	

下面就来写LogoutServlet.java代码

2.2 新建LogoutServlet.java

在web.servlet包新建一个LogoutServlet.java， servlet代码内容如下。

package com.anthony.web.servlet;

import java.io.IOException;
import java.lang.reflect.InvocationTargetException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.beanutils.BeanUtils;

import com.anthony.domain.User;
import com.anthony.service.UserService;
import com.anthony.service.impl.UserServiceImpl;


public class LogoutServlet extends HttpServlet {

	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		req.setCharacterEncoding("UTF-8");
		resp.setContentType("text/html;charset=UTF-8");
		//点击注销，意味session对象要销毁
		req.getSession().invalidate();
		//往首页跳转
		resp.sendRedirect(req.getContextPath()+"/index.jsp");
	}

	protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		doGet(req,resp);
	}
	
	

}

重新部署之后，登录成功，点击注销，会跳转到主页。