Servlet设置简单的登录系统

Servlet+Session 设置简单的登录系统

  1. 首先创建一个登录jsp页面
 1 <body>
 2         <form  action="${pageContext.request.contextPath }/loginServlet"  name="actionForm" id="actionForm"  method="post" >
 3             <dl>
 4                 <dt>用户名：</dt>
 5                 <dd><input type="text" id="userCode" name="userCode"/> <span id="userCodeSpan"></span> </dd>
 6                 <dt>密　码：</dt>
 7                 <dd><input type="password"  id="userPassword" name="userPassword"/><span id="userPasswordSpan"></span></dd>
 8             </dl>
 9             <div class="buttons">
10                 ${error }
11                 <input type="button"   value="登录系统" onclick="validate();" />
12                 <input type="reset"  value="重　　填" class="input-button" />
13             </div>
14         </form>
15 
16 
17 </body>

　　2.创建一个Servlet类

public class LoginServlet extends HttpServlet {

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
	 *      response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		// TODO Auto-generated method stub
		doPost(request, response);
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
	 *      response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		// TODO Auto-generated method stub
		//获取用户名和密码
		String name = request.getParameter("userCode");
		String password = request.getParameter("userPassword");
		//拿着信息去数据库查询是否存在
		UserService us = new UserServiceImpl();
		User user = new User();
		user = us.getUserInfo(name, password);
		
		if(user!=null) {
			//登陆后设置用户session
			request.getSession().setAttribute("userSession", user);
			//如果数据库存在该用户就重定向到首页
			response.sendRedirect("/news/jsp/admin/admin.jsp");
			
		}else {
			response.sendRedirect("/news/jsp/login.jsp");
			
		}
	}

}
  • 　　先从跳转页面获取name和password,然后去数据库查询信息是否存在
  • 如果存在就跳转到登录的首页, 跳转之前先设置把用户信息设置进session里, 登录以后访问网站的其他页面不用在登录
  • 如果不存在重定向回登录页面

　　3.写好severlet类后要在web.xml里配置一下 具体从跳转到找到你写的servlet类的过程如下 1.2.3.4

  <servlet>
    <description></description>
    <display-name>LoginServlet</display-name>
    <servlet-name>LoginServlet</servlet-name>//3.根据名字找到这个类
    <servlet-class>com.kgc.web.servlet.LoginServlet</servlet-class>//4.最后找到这个类所在的具体位置
  </servlet>
  <servlet-mapping>
    <servlet-name>LoginServlet</servlet-name>//2.根据相对路径找到这个servlet名字
    <url-pattern>/loginServlet</url-pattern>//1.提交表单时会定向到这个相对路径
  </servlet-mapping>

4.如果存在下一步会重定向到response.sendRedirect("/news/jsp/admin/admin.jsp");这个路径,但是进入这个页面前会先经过过滤器

 1 public class LoginFilter implements Filter {
 2 
 3     public void doFilter(ServletRequest request, ServletResponse response,
 4             FilterChain chain) throws IOException, ServletException {
 5         //对登录进行验证
 6         HttpServletRequest rq = (HttpServletRequest)request;
 7         HttpServletResponse rp = (HttpServletResponse)response;
 8         User userSession = (User)rq.getSession().getAttribute("userSession");
 9         if(null == userSession){
10             rp.sendRedirect("/news/jsp/error.jsp");
11         }else{
12             chain.doFilter(request, response);
13         }
14     }
15 
16     public void destroy() {
17         
18     }
19 
20     public void init(FilterConfig arg0) throws ServletException {
21         
22     }
23 
24 
25 }
View Code

过滤器会先检查session中user是否为空,如果为空将会重定向到登录页面,如果不为空将会chain.doFilter(request, response);继续传递下去

过滤器在web.xml中配置如下

1  <filter>
2     <filter-name>loginFilter</filter-name>
3     <filter-class>com.kgc.web.filter.LoginFilter</filter-class>
4   </filter>
5   <filter-mapping>
6     <filter-name>loginFilter</filter-name>
7     <url-pattern>/jsp/admin/*</url-pattern>//设置过滤的范围,admin下的所有jsp页面
8   </filter-mapping>

 

posted @ 2019-06-10 20:04  Mr.Li[0]  阅读(706)  评论(0)  编辑  收藏  举报