使用session和cookie实现免登陆

原文链接：http://www.jb51.net/article/108764.htm

参考文件：http://blog.csdn.net/a997208868/article/details/47787305

后台管理页面往往需要登录才可以进行操作，这时就需要Seession来记录登录状态

要实现起来也是非常简单，只需要自定义一个HandlerInterceptor就行了

自定义的HandlerInterceptor也只有短短几行代码

public class LoginInterceptor implements HandlerInterceptor {

  @Override
  public void afterCompletion(HttpServletRequest request,
                HttpServletResponse response, Object obj, Exception err)
      throws Exception {
  }

  @Override
  public void postHandle(HttpServletRequest request, HttpServletResponse response,
              Object obj, ModelAndView mav) throws Exception {

  }

  @Override
  public boolean preHandle(HttpServletRequest request, HttpServletResponse response,
               Object obj) throws Exception {
    //获取session里的登录状态值
    String str = (String) request.getSession().getAttribute( "isLogin" );
    //如果登录状态不为空则返回true，返回true则会执行相应controller的方法
    if (str!= null ){
      return true ;
    }
    //如果登录状态为空则重定向到登录页面，并返回false，不执行原来controller的方法
    response.sendRedirect( "/backend/loginPage" );
    return false ;
  }
}

Controller代码

@Controller
@RequestMapping ( "/backend" )
public class BackendController {

  @RequestMapping (value = "/loginPage" , method = {RequestMethod.GET})
  public String loginPage(HttpServletRequest request,String account, String password){
    return "login" ;
  }

  @RequestMapping (value = "/login" , method = {RequestMethod.POST})
  public String login(HttpServletRequest request,RedirectAttributes model, String account, String password){
    //验证账号密码，如果符合则改变session里的状态，并重定向到主页
    if ( "jack" .equals(account)&& "jack2017" .equals(password)){
      request.getSession().setAttribute( "isLogin" , "yes" );
      return "redirect:IndexPage" ;
    } else {
      //密码错误则重定向回登录页，并返回错误，因为是重定向所要要用到RedirectAttributes
      model.addFlashAttribute( "error" , "密码错误" );
      return "redirect:loginPage" ;
    }
  }
  //登出，移除登录状态并重定向的登录页
  @RequestMapping (value = "/loginOut" , method = {RequestMethod.GET})
  public String loginOut(HttpServletRequest request) {
    request.getSession().removeAttribute( "isLogin" );
    return "redirect:loginPage" ;
  }
  @RequestMapping (value = "/IndexPage" , method = {RequestMethod.GET})
  public String IndexPage(HttpServletRequest request){
    return "Index" ;
  }

}

spring的配置

< mvc:interceptors >

  < mvc:interceptor >

    < mvc:mapping path = "/backend/**" />

    < mvc:exclude-mapping path = "/backend/loginPage" />
    < mvc:exclude-mapping path = "/backend/login" />
    < bean class = "com.ima.Interceptor.LoginInterceptor" > bean >
  mvc:interceptor >
mvc:interceptors >

一个简单的Session实现登录认证系统就这样完成了，如果想登录状态退出浏览器后仍保留一段时间的可以将Session改为Cookie

一般情况下我们都会使用Cookie

Cookie和Session的方法差不多

使用Cookie的自定义HandlerInterceptor

public class LoginInterceptor implements HandlerInterceptor {

  @Override
  public void afterCompletion(HttpServletRequest request,
                HttpServletResponse response, Object obj, Exception err)
      throws Exception {
  }

  @Override
  public void postHandle(HttpServletRequest request, HttpServletResponse response,
              Object obj, ModelAndView mav) throws Exception {

  }

  @Override
  public boolean preHandle(HttpServletRequest request, HttpServletResponse response,
               Object obj) throws Exception {
//    获取request的cookie
    Cookie[] cookies = request.getCookies();
    if ( null ==cookies) {
      System.out.println( "没有cookie==============" );
    } else {
//      遍历cookie如果找到登录状态则返回true执行原来controller的方法
      for (Cookie cookie : cookies){
        if (cookie.getName().equals( "isLogin" )){
          return true ;
        }
      }
    }
//    没有找到登录状态则重定向到登录页，返回false，不执行原来controller的方法
    response.sendRedirect( "/backend/loginPage" );
    return false ;
  }
}

Controller的变化也不大

?

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@Controller @RequestMapping ( "/backend" ) public class BackendController { @RequestMapping (value = "/loginPage" , method = {RequestMethod.GET}) public String loginPage(HttpServletRequest request, String account, String password) { return "login" ; } @RequestMapping (value = "/login" , method = {RequestMethod.POST}) public String login(HttpServletRequest request, HttpServletResponse response, RedirectAttributes model, String account, String password) { if ( "edehou" .equals(account) && "aidou2017" .equals(password)) { Cookie cookie = new Cookie( "isLogin" , "yes" ); cookie.setMaxAge( 30 * 60 ); // 设置为30min cookie.setPath( "/" ); response.addCookie(cookie); return "redirect:IndexPage" ; } else { model.addFlashAttribute( "error" , "密码错误" ); return "redirect:loginPage" ; } } @RequestMapping (value = "/logOut" , method = {RequestMethod.GET}) public String loginOut(HttpServletRequest request, HttpServletResponse response) { Cookie[] cookies = request.getCookies(); for (Cookie cookie : cookies) { if (cookie.getName().equals( "isLogin" )) { cookie.setValue( null ); cookie.setMaxAge( 0 ); // 立即销毁cookie cookie.setPath( "/" ); response.addCookie(cookie); break ; } } return "redirect:loginPage" ; } @RequestMapping (value = "/IndexPage" , method = {RequestMethod.GET}) public String IndexPage(HttpServletRequest request) { return "Index" ; } }