Requestmethod‘GET‘notsupported405错误辨析总结

今天的错误比较常规&＃xff0c;虽然一开始没有想到&＃xff0c;但是后来还是很成功的解决了问题&＃xff0c;出现该错误的原因有很多&＃xff0c;这里只列举我出现的情况和解决方法&＃xff0c;以后有新的解决方法也会回来更新本博客&＃x1f9e1;

这个错误说实在话啊说好找也好找&＃xff0c;说不好找也不好找
在控制台报的错&＃xff1a;

在页面上&＃xff1a;

首先&＃xff0c;讲讲我想干什么&＃xff0c;是如何报错的&＃xff0c;对号入座&＃xff0c;如果大家发现和我的一致那就继续看下去吧&＃xff0c;如果不一致&＃xff0c;也请另请高明~

&＃x1f64b;‍♀️我想做的是使用SSM实现用户登录权限验证的功能&＃xff0c;具体我想实现&＃xff1a;
1️⃣只有登录后的用户才能访问系统中的主页
2️⃣没有登陆系统而直接访问主页&＃xff0c;则会被拦截器拦截&＃xff0c;并转发到登录界面&＃xff0c;同时在登录界面中给出提示信息。
3️⃣如果用户名和密码错误&＃xff0c;也会在登录界面给出登录信息

前面都是顺风顺水&＃xff0c;下面是我的LoginController.java

package com.xmonster.controller;import com.xmonster.pojo.Books;
import com.xmonster.pojo.User;
import com.xmonster.service.BookService;
import com.xmonster.service.UserServiceImpl;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpRequest;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.util.List;&＃64;Controller
public class LoginController {private UserServiceImpl userService;public UserServiceImpl getUserService() {return userService;}&＃64;Autowiredpublic void setUserService(UserServiceImpl userService) {this.userService &＃61; userService;}// 向用户登陆页面跳转&＃64;RequestMapping(value &＃61; "/tologin")public String toLogin(){return "login";}
//用户登录&＃64;RequestMapping(value &＃61; "/login",method &＃61; RequestMethod.POST)public String login(User user, Model model, HttpSession session, HttpServletRequest request){String userName &＃61; user.getName();String userPwd &＃61; user.getPwd();System.out.println(userName&＃43;userPwd);if(userName !&＃61; null && userPwd !&＃61; null){List<User> userList &＃61; userService.selectAllUser();for (User user1 : userList) {if(userName.equals(user1.getName()) && userPwd.equals(user1.getPwd())){session.setAttribute("USER_SESSION",user);return "redirect:/book/allBook";}}}model.addAttribute("msg", "用户名或密码错误&＃xff0c;请检查&＃xff01;");return "login";}//退出登录&＃64;RequestMapping(value &＃61; "/logout")public String logOut(HttpSession session){session.invalidate();return "redirect:/login";}}


拦截器&＃xff1a;下面可以看到我有很多的输出&＃xff0c;那是在后面为了测试做的&＃xff0c;可以忽略&＃x1f920;

package com.xmonster.interceptor;import com.xmonster.pojo.User;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;public class LoginInterceptor implements HandlerInterceptor {&＃64;Overridepublic boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {String requestURI &＃61; request.getRequestURI();if(requestURI.indexOf("/login")>&＃61;0){System.out.println("1通行&＃xff01;1");return true;}HttpSession session &＃61; request.getSession();User user &＃61; (User)session.getAttribute("USER_SESSION");if(user!&＃61;null){System.out.println("2通行&＃xff01;2");return true;}System.out.println("未登录&＃xff0c;不通行&＃xff01;&＃xff01;");request.setAttribute("msg", "你还没登录&＃xff0c;请先登录&＃xff01;");request.getRequestDispatcher("/WEB-INF/jsp/login.jsp").forward(request, response);return false;}&＃64;Overridepublic void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {// HandlerInterceptor.super.postHandle(request, response, handler, modelAndView);}&＃64;Overridepublic void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {// HandlerInterceptor.super.afterCompletion(request, response, handler, ex);}
}

html我就只展示重点的代码内容&＃xff0c;其他不展示&＃xff0c;login.jsp:


<div class&＃61;"container" id&＃61;"login"><div class&＃61;"row justify-content-center"><div class&＃61;"col-lg-8"><div class&＃61;"login"><h1>Loginh1><%-- 如果用户都填完信息之后后台检测不到该用户--%>${msg};<form action&＃61;"${pageContext.request.contextPath}/login" method&＃61;"post"><div class&＃61;"form-group"><input type&＃61;"text" class&＃61;"form-control" id&＃61;"username" name&＃61;"name" placeholder&＃61;"Enter username"><span id&＃61;"userInfo">span>div><div class&＃61;"form-group"><input type&＃61;"password" class&＃61;"form-control" id&＃61;"pwd" name&＃61;"pwd" placeholder&＃61;"Password"><span id&＃61;"pwdInfo">span>div><div class&＃61;"form-check"><label class&＃61;"switch"><input type&＃61;"checkbox"><span class&＃61;"slider round">span>label><label class&＃61;"form-check-label">Remember melabel><label class&＃61;"forgot-password"><a href&＃61;"#">Forgot Password?a>label>div><br><button type&＃61;"submit" class&＃61;"btn btn-lg btn-block btn-success">Sign inbutton>form>div>div>div>div>


问题出在哪&＃xff1f;
首先&＃xff0c;在我们请求一个页面的时候&＃xff0c;默认都是GET方法请求的&＃xff0c;像这样&＃xff1a;

当我请求/logout时候&＃xff1a;


到这里其实就可以看出来了&＃xff0c;在我请求了/logout的时候&＃xff0c;按照上面的代码我们知道他肯定会重定向到/login&＃xff0c;但是&＃xff0c;我们的/login增加了这段代码&＃xff1a;

而且现在就有一个问题
那就是为什么/tologin可以请求到login.jsp&＃xff0c;但是/logout重定向到login.jsp就会报405的u错误呢&＃xff1f;
为此我特意将/tologin的返回值也设置成了重定向的形式&＃xff0c;结果证明也发生了405错误&＃xff0c;那么问题就很明显了&＃x1f4a5;&＃x1f4a5;&＃x1f4a5;
问题就出在了method &＃61; RequestMethod.POST
&＃x1f49c;
回顾method元素&＃xff0c;它声明了HTTP请求方法的类型&＃xff0c;所有的处理方法会处理同一个URL进来的请求&＃xff0c;但是具体要看指定的HTTP类型来决定哪个方法处理&＃xff0c;显然&＃xff0c;我一开始使用了POST方法在/login的请求中&＃xff0c;也就是说只有你这个方法是POST才可以调用我的/login请求&＃xff0c;但是像/logout它本身就是GET请求&＃xff0c;所以不匹配&＃xff0c;不一致&＃xff0c;导致405错误的发生。