SSM———访问controller404错误

搭建SSM项目时访问controller层时，显示404错误，404顾名思义：404页面是客户端在浏览网页时，服务器无法正常提供信息，或是服务器无法回应，且不知道原因所返回的页面。

1.首先怀疑是内部逻辑错误，先创建测试类，测试数据库是否连接成功

package net.zzqd.mmall.test;

import net.zzqd.mmall.pojo.User;
import net.zzqd.mmall.service.IUserService;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

/**
 * @author zqnh
 * @date 2019/7/26 on 12:53.
 */
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = {"classpath*:/applicationContext*.xml"})
public class Test1
{
    @Autowired
    private IUserService iUserService;
    @Test
    public void test()
    {
        User user  = new User();
        user.setPassword("root");
        user.setUsername("root");
        user.setAnswer("哈哈");
        user.setQuestion("哈哈");
        user.setPhone("15151515151");
        user.setEmail("7151515@qq.com");
        user.setId(50);
        user.setRole(0);
        iUserService.register(user);
        if(iUserService.register(user)!= null)
        {
            System.out.println("注册成功");
        }
        else
        {
            System.out.println("注册失败");
        }
    }

}

数据库中插入了这条数据，数据库连接没问题。

访问controller,还是404

2.紧接着，查看web.xml中是否有DispatcherServlet

<servlet>
        <servlet-name>dispatcher</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>dispatcher</servlet-name>
        <url-pattern>*.do</url-pattern>
    </servlet-mapping>

也有

3.看WEB-INF中dispatcher-servlet.xml中是否有，这是开启mvc模式

<mvc:annotation-driven/>

4.然后又看Controller层里的RequestMapping中的参数，也没问题

package net.zzqd.mmall.controller.portal;

import net.zzqd.mmall.common.Const;
import net.zzqd.mmall.common.ResponseCode;
import net.zzqd.mmall.common.ServerResponse;
import net.zzqd.mmall.pojo.User;
import net.zzqd.mmall.service.IUserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;

import javax.servlet.http.HttpSession;

/**
 * @author zqnh
 * @date 2019/7/25 on 11:00.
 */
@Controller
@RequestMapping("/user/")
public class UserController
{
    @Autowired
    private IUserService iUserService;
    /**
     * 用户登陆
     * @param username
     * @return
     */

    @RequestMapping(value = "login.do",method = RequestMethod.POST)
    @ResponseBody
    public ServerResponse<User> login(String username, String password, HttpSession session)
    {
        ServerResponse<User> response = iUserService.login(username,password);
        if(response.isSuccess())
        {
            session.setAttribute(Const.CURRENT_USER,response.getData());
        }
        return response;
    }

    @RequestMapping(value = "logout.do",method = RequestMethod.POST)
    @ResponseBody
    public ServerResponse<String> logout(HttpSession session)
    {
        session.removeAttribute(Const.CURRENT_USER);
        return ServerResponse.createBySuccess();
    }

    @RequestMapping(value = "register.do",method = RequestMethod.POST)
    @ResponseBody
    public ServerResponse<String> register(User user)
    {
        return iUserService.register(user);
    }

    @RequestMapping(value = "check_valid.do",method = RequestMethod.POST)
    @ResponseBody
    public ServerResponse<String> checkValid(String str,String type)
    {
        return iUserService.checkValid(str,type);
    }

    @RequestMapping(value = "get_user_info.do",method = RequestMethod.POST)
    @ResponseBody
    public ServerResponse<User> getUserInfo(HttpSession session)
    {
        User user = (User) session.getAttribute(Const.CURRENT_USER);
        if(user != null)
        {
            return ServerResponse.createBySuccess(user);
        }
        return ServerResponse.createByErrorMessage("用户未登录，无法获得当前用户信息");
    }

    @RequestMapping(value = "forget_get_question.do",method = RequestMethod.POST)
    @ResponseBody
    public ServerResponse<String> forgetGetQuestion(String username)
    {
        return iUserService.selectQuestion(username);
    }

    @RequestMapping(value = "forget_check_answer.do",method = RequestMethod.POST)
    @ResponseBody
    public ServerResponse<String> forgetCheckAnswer(String username,String question,String answer)
    {
        return iUserService.checkAnswer(username,question,answer);
    }

    @RequestMapping(value = "forget_reset_password.do",method = RequestMethod.POST)
    @ResponseBody
    public ServerResponse<String> forgerRestPassword(String username,String passwordNew,String forgetToken)
    {
        return iUserService.forgetRestPassword(username,passwordNew,forgetToken);
    }

    @RequestMapping(value = "reset_reset_password.do",method = RequestMethod.POST)
    @ResponseBody
    public ServerResponse<String> resetPassword(HttpSession session,String passwordOld,String passwordNew)
    {
        User user = (User)session.getAttribute(Const.CURRENT_USER);
        if(user == null)
        {
            return ServerResponse.createByErrorMessage("用户未登录");
        }
        return iUserService.resetPassword(passwordOld,passwordNew,user);
    }

    @RequestMapping(value = "reset_imformation.do",method = RequestMethod.POST)
    @ResponseBody
    public ServerResponse<User> update_information(HttpSession session,User user)
    {
        User currentUser = (User)session.getAttribute(Const.CURRENT_USER);
        if(currentUser == null)
        {
            return ServerResponse.createByErrorMessage("用户未登录");
        }
        user.setId(currentUser.getId());
        user.setUsername(currentUser.getUsername());
        ServerResponse<User> response = iUserService.updateInformation(user);
        if(response.isSuccess())
        {
            session.setAttribute(Const.CURRENT_USER,response.getData());
        }
        return response;
    }

    @RequestMapping(value = "get_imformation.do",method = RequestMethod.POST)
    @ResponseBody
    public ServerResponse<User> get_information(HttpSession session)
    {
        User currentUser = (User)session.getAttribute(Const.CURRENT_USER);
        if(currentUser == null)
        {
            return ServerResponse.createByErrorCodeMessage(ResponseCode.NEED_LOGIN.getCode(),"未登录，需要强制登陆");
        }
        return iUserService.getInformation(currentUser.getId());
    }
}

5.然后看applicationContext.xml中是否配有视图解析器，由于这是接口测试，没有前台页面，故没影响

6.最后！！！，我发现Tomcat启动成功后，弹出的页面地址如下

因为我之前输入的地址都是

http://localhost:8088/user/login.do?username=root&password=root

然后我输入项目名

http://localhost:8088/mmall_war_exploded/user/login.do?user=root&password=root

重点来了，突然发现405错误，405错误，是请求错误，比如GET请求输入的是POST请求，或者是POST请求输入的是GET请求，然后我再Postman里测试，成功返回参数，大功告成。

http://localhost:8088/mmall_war_exploded/user/login.do

谨记：发现问题 分析问题 解决问题