登陆成功后返回前一个页面

原文地址：http://blog.csdn.net/alanzyy/article/details/50562362

之前自己写了一个Web日志工具，使用Spring MVC+mybatis进行实现。由于我自己一天到晚都要使用，而有时页面会放在那里一段时间，就常会遇到session过期后跳转到登陆界面进行登陆。但是登陆后是转向了一个默认界面，这样我每次都还在多一次点击才能来到目标页面。于是，我必须要解决登陆之后跳转到前一个页面的问题以提高效率。

首先，我使用了SessionFilter对Session进行过滤，在Session过期时就会在这个方法中转向到login界面。

public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {    HttpSession session = ((HttpServletRequest) request).getSession();    HttpServletResponse rep = (HttpServletResponse) response;    HttpServletRequest req = (HttpServletRequest) request;    String url = req.getRequestURI();    if (url.contains("user/login")            || url.endsWith(".css")            || url.endsWith(".js")            || url.endsWith(".png")            || url.endsWith(".jpg")) {        chain.doFilter(request, response);    } else if ((session == null || session.getAttribute("user") == null)) {        rep.sendRedirect(req.getContextPath() + "/user/login);    } else {        chain.doFilter(request, response);    }}

然后，在LoginController中分GET和POST对用户登陆进行处理。

@RequestMapping(value = "/login", method = RequestMethod.GET)public ModelAndView login() {    final ModelAndView m = new ModelAndView("login");    return m;}@RequestMapping(value = "/login", method = RequestMethod.POST)public ModelAndView login(HttpSession session, String userName, String password) {    ReturnStatus rs = service.login(userName, MD5Tool.getMD5(password.getBytes()));    if (rs.getCode() == 1) {        session.setAttribute("user", service.get(userName));        return new ModelAndView("redirect:/task/week");    } else {        final ModelAndView m = new ModelAndView("login");        m.addObject("message", "用户名或者密码不正确，请重新输入");        return m;    }}

解决方案

我首先想到的就是在filter中转向到login页面时，将登陆成功后要转向的页面fromUrl传过去。假设原始链接是：http://localhost:8084/personal/task/update?id=DTASK1167778733413045&mode=week。

1. req.getRequestURI()，获取到的是/personal/task/update，不带query string，不符合
2. req.getRequestURL()，获取到的是http://localhost:8084/personal/task/update，也不带query string，不符合
3. 于是我百度了一下，找到一下方法可以获得完整的请求url(http://localhost:8084/personal/task/update?id=DTASK1167778733413045&mode=week)，但是遗憾的是POST过来的数据还是无法

   • public static String getUrl(HttpServletRequest req) {    String reqUrl = req.getRequestURL().toString();    String queryString = req.getQueryString();    if (queryString != null) {        reqUrl += "?" + queryString;    }    return reqUrl;}

4. 我试图从request中把POST过来的数据设置到response的Header中，但是在login页面经过SpringMVC后再次分发我又不会(感觉会很麻烦)

   • private void setHeader(HttpServletRequest req, HttpServletResponse rep) {    for (Map.Entry<String, String[]> entry : req.getParameterMap().entrySet()) {        try {            String name = entry.getKey();            String value = new String(req.getParameter(name).getBytes("ISO8859-1"), "UTF8");            rep.setHeader(name, value);        } catch (UnsupportedEncodingException ex) {            Logger.getLogger(SessionFilter.class.getName()).log(Level.SEVERE, null, ex);        }    }}

5. 于是决定，在POST的情况下就不再做POST操作，而是转向到POST之前的界面(这样有丢失数据的危险，暂时先这样吧)

   • from Url = req.getHeader("Referer")

最终，思路确定如下：Session过滤时，如果是POST过来的，就取前一个页面的url(第5点中的方法)，如果是其他请求方式过来的(主要是GET)，就使用当前要转向的url(第3点中的方法)。将url通过GET方式传入到login页面后，POST login时也带到后台，待确认登陆成功后转向到该url。

最终代码

SessionFilter

public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {    HttpSession session = ((HttpServletRequest) request).getSession();    HttpServletResponse rep = (HttpServletResponse) response;    HttpServletRequest req = (HttpServletRequest) request;    String url = req.getRequestURI();    if (url.contains("user/login")            || url.endsWith(".css")            || url.endsWith(".js")            || url.endsWith(".png")            || url.endsWith(".jpg")) {        chain.doFilter(request, response);    } else if ((session == null || session.getAttribute("user") == null)) {        String fromUrl;        if ("POST".equalsIgnoreCase(req.getMethod())) {            fromUrl = req.getHeader("Referer");        } else {            fromUrl = getUrl(req);        }        rep.sendRedirect(req.getContextPath() + "/user/login?fromUrl=" + URLEncoder.encode(fromUrl, "UTF8"));    } else {        chain.doFilter(request, response);    }}public static String getUrl(HttpServletRequest req) {    String reqUrl = req.getRequestURL().toString();    String queryString = req.getQueryString();    if (queryString != null) {        reqUrl += "?" + queryString;    }    return reqUrl;}

LoginController

@RequestMapping(value = "/login", method = RequestMethod.GET)public ModelAndView login(HttpServletRequest request, @RequestParam(defaultValue = "") String fromUrl) {    final ModelAndView m = new ModelAndView("login");    m.addObject("fromUrl", fromUrl);    return m;}@RequestMapping(value = "/login", method = RequestMethod.POST)public ModelAndView login(HttpSession session, String userName, String password,        @RequestParam(defaultValue = "") String fromUrl) {    ReturnStatus rs = service.login(userName, MD5Tool.getMD5(password.getBytes()));    if (rs.getCode() == 1) {        session.setAttribute("user", service.get(userName));        if (fromUrl.equals("")) {            return new ModelAndView("redirect:/task/week");        } else {            return new ModelAndView("redirect:" + fromUrl);        }    } else {        final ModelAndView m = new ModelAndView("login");        m.addObject("message", "用户名或者密码不正确，请重新输入");        m.addObject("fromUrl", fromUrl);        return m;    }}