Java - HTTP 状态 404 - 未找到

Question

我正在学习 spring mvc 并想测试一些非常简单的基于注释的控制器，它在主页上运行良好，但是当我进入 /home/user 时它给了我 HTTP 状态404 – Not Found 错误，我没有找到任何可以修复它的方法。

web.xml

<web-app version="3.1" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd">
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>/WEB-INF/applicationContext.xml</param-value>
    </context-param>
    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>

    <!--####################################-->


    <servlet>
        <servlet-name>dispatcher</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <load-on-startup>2</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>dispatcher</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>
    <welcome-file-list>
        <welcome-file>redirect.jsp</welcome-file>
    </welcome-file-list>
</web-app>

调度程序-servlet.xml

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans 
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context 
        http://www.springframework.org/schema/context/spring-context.xsd">

    <bean class="org.springframework.web.servlet.mvc.support.ControllerClassNameHandlerMapping"/>

    <context:component-scan base-package="spring" />

    <bean class="org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping"/>

    <bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter"/>

    <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <property name="suffix" value=".jsp"/>
    </bean>

    <!--<bean id="viewResolver"

</beans>

HomeController.java

package spring.controllers;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.servlet.ModelAndView;

@Controller
//@RequestMapping(value = "/home")
public class HomeController {

    @RequestMapping(value = "/home", method = RequestMethod.GET)
    public String showHomeMessage() {
        return "home";
    }
}

UserController.java

package spring.controllers;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

@Controller
@RequestMapping("/home/user")
public class UserController {

    @RequestMapping(method = RequestMethod.GET)
    public String welcomeMessage(){
        return "user";
    }
}

redirect.jsp 只是使用sendRedirect() 方法并重定向到home.jsp。

home.jsp 和 user.jsp 只是打印一个简单的 hello 消息

我哪里做错了？

问候

Answer 1

您是否尝试过嵌套RequestMapping？像这样的……

@Controller
@RequestMapping(value = "/home")
public class HomeController {

    @RequestMapping(method = RequestMethod.GET)
    public String showHomeMessage() {
        return "home";
    }

    @RequestMapping(value = "/user", method = RequestMethod.GET)
    public String welcomeMessage(){
        return "user";
    }
}

我不确定您是否需要为 showHomeMessage 赋值（即 value="/"）。

Answer 2

查看this 小示例后，我认为您的问题与您没有使用@Controller 注释指定@ResponseBody 的事实有关。然而，如果你使用 @RequestController 注释，仅仅暗示一个 String 类型就足够了，因为它结合了 @Controller 和 @ResponseBody 的使用

@Controller
@RequestMapping("/home/user")
public class UserController {

    @RequestMapping(method = RequestMethod.GET)
    public @ResponseBody String welcomeMessage(){
        return "user";
    }
}

同一块的替代方案是......

@RestController
@RequestMapping("/home/user")
public class UserController {

    @RequestMapping(method = RequestMethod.GET)
    public String welcomeMessage(){
        return "user";
    }
}

当然这个小例子没有演示MediaType等等，但希望你明白。